SUBMARINE REPORT
DEPTH CHARGE, BOMB, MINE, TORPEDO
AND GUNFIRE DAMAGE
INCLUDING LOSSES IN ACTION
7 DECEMBER, 1941 TO 15 AUGUST, 1945
VOLUME II
Preliminary Design Branch
Bureau of Ships
Navy Department
1 January 1949
WAR DAMAGE REPORT No. 58
Printed By U. S. Hydrographic Office
SECTION XV
BEHAVIOR OF UNDERWATER NON-CONTACT EXPLOSIONS
15-1. The principal Japanese anti-submarine weapons were the depth charge and bomb, both designed to achieve their destructive effect by non-contact underwater explosion in close proximity to the target. An explanation of the behavior of such non-contact underwater explosions has therefore been included in this report.
15-2. The action of an explosive is the result of a purely internal chemical conversion which liberates a large quantity of gas and heat within a very short period of time. The total quantity of energy produced by the detonation of a conventional explosive is much less than that given off by combustion of equal weight of any of the standard fuels. However, the rate at which the energy is released, due to the velocity with which the reaction travels through the explosive, is very much greater. Detonation is an action characteristic of high explosives. Substantially complete and virtually instantaneous transformation of a high explosive charge into energy and decomposition products is called a "high order" detonation. All underwater explosive weapons are intended to detonate high order.
15-3. The sequence of events which occurs in the water as the result of an underwater explosion is of considerable interest. When a high explosive material, such as used in a depth charge or depth bomb, is detonated underwater, the initial action that occurs is the creation of a detonation wave which travels through the explosive material at a very high velocity, approximately 20,000 feet per second, and converts the solid charge to a dense gas at a high temperature and pressure without appreciable change in volume. It has been estimated that the initial pressure of the gas bubble resulting from underwater detonation of explosives having properties similar to TNT is of the order of one to two million pounds per square inch. Under this tremendous initial pressure, and considering the detonation to have occurred at a sufficient depth so that surface effects do not appreciably alter the subsequent phenomena, the gaseous product of the detonation then suddenly starts to expand, suddenly compresses the water around the charge, and thereby sets up in the water a shock wave. The shock wave consists of the shock front, which is a discontinuity of pressure typified by an almost instantaneous pressure rise, followed by an approximately exponential decay of pressure with time and by, theoretically at least, a long tail of pressure too low to be of practical interest (Figure 15-1). This shock wave travels faster than the subsequent expansion of the gas bubble, leaves the vicinity of the explosion and is propagated radially outward in all directions (Photo 15-1). Except for the regions of very high pressure in the immediate vicinity of the explosion, the shock wave obeys the laws of spherical propagation of sound reasonably well, i.e., as the wave advances its peak pressure falls off a little faster than the inverse of the distance from the center of the explosion, the positive time duration of the pressure pulse increases slightly with increasing distance, and the wave travels only a little faster than the speed of sound in water (about 4900 feet per second). The water, after the wave has passed, remains substantially undisturbed. This initial shock wave or pressure pulse, the positive pressure portion of which lasts for only a few milli-seconds in passing any particular point as it travels radially outward, is believed to account for the major portion of the destructive effect of a
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close underwater detonation and all of the remote action or destructive effect of a distant underwater detonation. When received from a considerable distance, the shock wave is discernible as a "metallic ping" on a submarine pressure hull. In a general way, the cause of damage to a ship from underwater explosions may be thought of as the sudden delivery at the ship of energy at high potential, i.e., the energy delivered by the shock wave. The energy contained in the primary shock wave is approximately one-quarter of the total energy released by the detonation of the explosive charge.
15-4. Simultaneously with the dispatch of the shock wave, the enormous initial pressure created by the transformation of the explosive charge into gas imparts a high velocity in a radial direction to the surrounding water and the gas bubble starts to expand outward with an initial velocity greater than that of an ordinary gun projectile. The kinetic energy thus imparted in mass flow to the water may be a significant damaging factor in very close explosions but is otherwise of only academic interest since the water velocity falls off rapidly with distance from the center of the explosion. Because of the high momentum imparted to the water, the bubble expansion continues beyond the point at which the gas pressure within equals the absolute hydrostatic head of the surrounding water and atmosphere. Eventually, however, the opposing external hydrostatic pressure brings the expansion to a halt, the pressure within the bubble at this point being of the order of only a few pounds per square inch, and reversed flow of water commences inward toward the center of the gas bubble. The gas pressure then increases rapidly as the size of the bubble diminishes, but the motion again overshoots the point of hydrostatic equilibrium due to the inward momentum of the water. At the extreme compression on this first contraction the gas pressure within the bubble reaches a peak estimated to be about 10,000 pounds per square inch. This high pressure initiates a second pressure wave or pulse in the surrounding water, having maximum intensity at the time of minimum bubble diameter. While of considerably less intensity than the initial shock wave, this second pressure wave is of many times greater duration and consequently may be a significant damaging factor to some types of targets.
15-5. The cycle of expansion and contraction may then repeat several more times in the manner described above until all of the energy has been dissipated or the bubble has either vented itself by breaking the surface of the water or has broken up into numerous small bubbles of no consequence. Due to energy losses, the bubble oscillations rapidly dampen out, successive maximum bubble sizes becoming smaller and successive minimum bubble sizes becoming larger. With each succeeding contraction, pressure waves or pulses of progressively decreasing intensity will be emitted. Photo 15-2 is an excellent high-speed camera study of gas bubble oscillations produced by the underwater detonation of a No. 8 blasting cap, roughly equivalent to 1/2 gram of tetryl. Figure 15-1 below depicts the phase relationship between the gas bubble oscillations and the pressure waves.
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15-6. A secondary effect associated with an underwater explosion, which may in certain circumstances be of importance, is that of pressure wave reflection from the surface or from the bottom. If an explosive charge is detonated at a location such that either the sea surface or the bottom is at a distance comparable to or less than the distance to the target, then reflected waves from either the surface or the bottom may greatly intensify or diminish the direct pressure wave at the target by interference. The pressure wave is reflected from the sea surface as a tension wave, subject to the restriction that water can support only a limited negative pressure prior to the occurrence of cavitation. If the detonation is shallow, surface reflections can therefore very materially diminish the main pressure pulse by interference. However, if the detonation occurs close over a hard ocean floor, i.e., rock, sand, etc., the pressure pulse upward and to the sides will be considerably increased over that for a similar detonation in free water where the ocean floor is relatively distant, the amplification being caused by reflection of energy from the hard bottom. The pressure pulse will theoretically be doubled for charges which are detonated on a perfectly rigid surface. This factor would appear to operate in favor of anti-submarine forces attacking a target running close to hard ocean floors.
15-7. The surface phenomena over an underwater explosion is of interest. Three distinct effects can be noted under certain conditions.1
(a) Almost simultaneously with the explosion, the surface of the water is agitated by the pressure wave and a light spray may be thrown up. This effect is not noticeable if the explosion is very deep.
(b) During the first second or two after a shallow explosion, the water rises in a flattish "dome" which is often white in color and may attain a height of 50 feet or more. As the depth of the explosion is increased, the maximum height of the dome diminishes, and finally, at relatively great depths, no dome is formed (e.g., there is none from 300 pounds of TNT 150 feet deep).
(c) Plumes of spray may be thrown up by the gaseous products of the explosion venting through the surface. If the charge is only a few feet below the surface, the plumes break through the dome while the latter is still rising, and may attain a height of many hundreds of feet. As the depth of the explosion is increased, the plumes become less marked and also appear later; they may break through the dome at the instant the latter has attained its greatest height, or when it is sinking again, or the plumes may not appear until after the dome has disappeared. Finally, at great depths, no plumes are formed, but a minute or so after the explosion a mass of creamy water pours up to the surface.
15-8. The phenomenon of repeated impact blows resulting from single underwater explosions, due to the intense pressure waves created by succeeding bubble contractions, was frequently noted by submarine personnel during the war.2 The outflow of water ahead of the expanding gas bubbles has also been commented on in numerous war patrol reports, being typically described as a "rush" of water about the ship or through
1 David Taylor Model Basin conf. Report No. 480 of October 1941.
2 Also observed as early as 1861 by Lt. Col. H. L. Abbot, USA, while investigating submarine mines for the Corps of Engineers, U.S. Army. Observed during TROUT (SS202) depth charge tests off Portsmouth, N.H. in 1941.
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Photo 15-1: German photograph showing gas bubble and shock front 0.000014 second after detonation of 30 milligrams of explosive similar to TNT. This photograph is the result of a double exposure, the first being taken before detonation to show the exact position and shape of the explosive charge.
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Photo 15-2. High speed photographic history of gas bubble oscillations resulting from detonation of a No. 8 blasting cap underwater. This series of photographs is from David Taylor Model Basin conf. Report No. 512 of May 1943.
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the superstructure which could be distinctly heard inside the pressure hull after depth charge attacks. There are many cases on record where submerged submarines have been forced up or down due to these water movements, occasionally by as much as fifty feet. For example, during her fourth war patrol, BALAO (SS285) was forced down from 390 foot depth to 590 foot depth by a series of close depth charge detonations, each detonation causing the boat to increase depth by about 20 or 30 feet. HAWKBILL (SS366), in her action of 18 July 1945, was forced up from periscope depth by depth charges detonating under the hull and broached with a 20 degree up angle, exposing 60 feet of the bow. Various submarines have been heeled over by underwater explosions. GRENADIER (SS210), for example, reported a 10 to 15 degree heel as a result of a close bomb detonation (paragraph 8-5). The following description of depth charge detonations have been excerpted from various U.S. submarine war patrol reports and are representative of how such explosions sound to submarine personnel. BLUEGILL (SS242), while being depth charged at 340 foot depth on her third patrol, reported "The characteristics noted on far depth charges . . . were first a detonator click . . . and then bang!" BLUEGILL also described the more distant explosions as "a deep rumble increasing to the final boom." CABRILLA (SS288), while being depth charged at about 350 foot depth on her fourth patrol, reported "On almost all depth charges the familiar small detonation was followed by a large explosion and then swishing and falling waters were very evident". SALMON (SS182), while being depth charged at 150 feet depth during her first war patrol, reported for relatively distant depth charges that "As each charge went off there would be two pings on the hull which sounded as though two small nuts had been dropped, then after a period of one to two seconds the depth charge would be heard". FLYING FISH (SS229), depth charged at 250 foot depth during her second patrol, compared a depth charge detonation to a "thud similar to that expected when a 100-pound weight is dropped on the hull" followed shortly by the sound of the explosion and then "water would be heard rushing through the superstructure". PARGO (SS264), depth charged at about 350 foot depth during her fourth patrol, reported depth charge detonations which "rocked the boat in three separate and distinct pressure waves" and with a sound effect of "whoom -- whoom -- BO-om." Others described the sound of depth charges exploding in the distance as like a child playing with a toy hammer, very mild and weak, and the sound of fairly close charges as a "hard metallic click-bang". The metallic "click", "thud", or "ping" may be interpreted as the mechanical response of the hull structure to the arrival of the pressure pulse from an explosion and should have been distinguishable from the subsequent audible frequencies generated by the explosion, i.e., the "bang" or "boom", only for an explosion relatively distant from the hull. The increment of time between the arrival of the pressure wave and the audible frequencies will not be perceptible at very close ranges, the two arriving practically simultaneously. That this is so is evidenced by the fact that submarine personnel considered themselves safe if the "click" preceding the "boom" was distinguishable, since they found by experience that the depth charge would then detonate at a range which would not cause much, if any, damage. Contrary to the general impression, the pistols of Japanese depth charges contained no mechanism which could cause a "detonator click". The
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sound of "falling waters" referred to by CABRILLA was no doubt caused by the surface effects of the depth charge detonations, The "two pings" referred to by SALMON were perhaps due to a bottom reflection of the pressure pulse striking the hull shortly after the arrival of the direct pressure pulse.
15-9. The mechanics of damage by underwater explosions are not sufficiently well understood at this writing to permit precise evaluation of the relative effectiveness of the initial shock wave and each of the succeeding pressure waves in producing damage. It is known that for most practical situations, the initial shock wave of a non-contact underwater detonation can be considered the principal agent of damage. However, it has been demonstrated that under certain conditions it is possible for the additional pressure waves from succeeding compressions of the gas bubble to contribute further damage. For example, deep sea explosion tests by the Underwater Explosives Research Laboratory of the Bureau of Ordnance on small-scale (1/23) partial-length models, representing simplified SS285 Class submarine circular hull sections, showed that under combined hydrostatic loading (due to depth of the water) and explosive loading a well defined critical charge distance existed, such that at smaller distances general collapse of the test cylinder occurred whereas at greater distances only small local damage was observed.1 With the explosive charge just within the critical distance, it was found that general collapse did not occur until the arrival of the pressure pulse from the first contraction of the gas bubble. With the charge at approximately two-thirds this critical distance, however, the initial shock wave alone was of sufficient intensity and duration to cause collapse. It should be noted that due to the scale effect in interpretation of small model tests, the secondary pressure pulses from detonations of conventional depth charges and bombs in attacks on full size submarines would be somewhat less effective than indicated by the above tests.
15-10. For an explosion set off at a given distance from a circular submarine structure, secondary pressure pulses will have the greatest damaging effect when the charge is detonated below the hull.2 This is attributable to the tendency of the gas bubble to rise vertically under the influence of its buoyancy, especially in the contraction phase where relatively high velocities of ascent may be reached. It is therefore possible that the pressure pulse generated at the end of the first cycle of the bubble oscillation may be initiated close enough to the submarine to produce new or additional damage although the detonation itself was more distantly removed. Gas bubble oscillations resulting from detonations located near the side or above a submarine can generally be expected to rise and therefore increase their distance from the hull.
1 Office of Scientific Research and Development conf. Report No. 5417.
2 Both the Germans and French considered that for detonations occurring under a submarine, the limiting range within which serious damage could be expected would be double that for similar detonations located horizontally out from the side of the submarine--NavTechMisEu conf. Technical Report No. 227-45 of August 1945.
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For a charge which detonates relatively close to the side of a hull, however, vertical rise may be offset by the tendency of the gas bubble to migrate to the nearby rigid hull. Even for charges which detonate close above a submarine, the gas bubble may oscillate several times in very close proximity to the hull instead of rising.
15-11. Although considerable research and experimental work has been carried on by many nations, including the United States, in an effort to determine the damaging ranges of various anti-submarine non-contact explosive weapons, present experimental and theoretical knowledge is still not sufficient to compute accurate damage versus distance relationships for such weapons. The figures given by different investigators among various countries are considerably at variance. Unfortunately, the great amount of submarine war damage experience available to this country furnishes no precise quantitative information regarding the behavior of submarines when attacked with underwater non-contact explosives since the charge sizes, distances and relative points of detonation are not known in any of the cases. The damaging range for a given weight of specified explosive will of course vary widely among the different types of submarines, depending upon the energy absorption characteristics of the hull structure, the design and mounting of vital systems and machinery, and the circumstances of the attack, i.e., the orientation and distance of the charge with respect to the hull and the depth of submergence of the submarine.
15-12. A study of available data indicates that the detonation of 300 pounds of TNT will almost certainly cause pressure hull rupture and therefore presumed lethal damage when the center of detonation is within 25 feet of the pressure hull of a U.S. light-hulled submarine (SS284 and previous). Between 25 and 50 feet, rupture or marked permanent deformation of the pressure hull and/or serious damage to vital machinery and systems may generally be expected, depending upon the position of the charge relative to the hull and the submergence depth of the submarine. Moderate to minor damage to equipment and fittings can be expected from 50 to 100 feet and beyond. It appears that 40 feet would be a fair range to delineate the boundary between the zones of serious and moderate damage for 300-pound TNT charges used against U.S. light-hulled submarines at relatively shallow depths. The British estimated from their war experience that pressure hull rupture would be certain to occur on submarines of contemporary construction with the following combinations of explosive weights and ranges: 150 pounds of TNT at 14 feet; 300 pounds of TNT at 20 feet; 1200 pounds of TNT at 40 feet. German tests on U-446 in June and December of 1944 indicated that the detonation of 275 pounds of S1 explosive located 33 feet below the surface would cause marked permanent pressure hull deformation when within a distance of about 60 feet from the surfaced submarine.1 French calculations based upon research tests conducted in 1934 indicated that a double-hulled Paskal type submarine submerged to a keel depth of 50
1 NavTechMisEu conf. Technical Report No. 227-45 of August 1945. The German S1 explosive is similar in power to TPX.
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feet would sustain permanent pressure hull deformation from the detonation of a 440-pound charge (type of explosive not stated) when placed at approximately the same depth and closer than 50 feet to the pressure hull.
15-13. Figure 15-2 below contains a plot of the damaging-range curve developed by the Bureau in 1943 for light-hulled SS212 Class submarines (11/16-inch medium steel pressure hull) when subjected to non-contact underwater detonations of varying weights of explosives comparable in power to TNT. The data upon which this curve is based are sparse and incomplete and the accuracy of the curve should be regarded accordingly. Furthermore, it does not take into account the orientation of the charge with respect to the hull or the depth of submergence of the submarine, both of which have a marked effect on the range within which damage will occur. The region below the curve represents charge weight and distance relationships at which marked permanent deformation of the pressure hull and serious damage to vital machinery and systems may generally be expected. The curve should properly be thought of as a "band" rather than an exact line of demarkation. Included in the same figure is a second curve giving distances at which hull rupture can be expected to occur for target submarines having an assumed 7/8-inch high tensile steel pressure hull, equivalent to that of the SS285 Glass. This latter curve was developed by the Operations Evaluation Group from meager experimental evidence plus theoretical considerations and differs appreciably from the Bureau of Ships curve since it is based on positive rupture of a 7/8-inch thick HTS pressure hull rather than on permanent deformation only of an 11/16-inch thick MS pressure hull as in the case of the Bureau of Ships curve.1 The Operations Evaluation Group curve compares closely with the lethal ranges arrived at by the Underwater Explosive Research Laboratory after expanding the results of their small scale SS285 model tests (paragraph 15-9) to apply to a full size SS285 Class submarine (submerged to a depth of 50 feet).
FIGURE 15-2 DAMAGING RANGE CURVES FOR U.S. SUBMARINES (FOR SHALLOW SUBMERGENCE CONDITION ONLY)
1 Operations Evaluation Group conf. Research Report No. 40 of 28 April 1944.
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15-14. The effect of depth of submergence on the strength of submarines under dynamic loading (also termed pulse, shock or explosive loading) from non-contact underwater detonations is naturally a matter of much interest to both design and operating personnel. In the case of the SS285 Class small model tests cited in paragraph 15-9 above, the lethal distance of a given weight of explosive was observed to increase rapidly with depth. For example, the maximum charge distance at which cylinder collapse resulted was two and one-half times greater at 673 feet than at 200 feet.1 Qualitatively such an effect is to be expected, since the stress due to explosive loading is superimposed on that already present in the structure due to hydrostatic pressure and therefore the lethal distance should increase rapidly as the absolute hydrostatic collapsing depth of the hull is approached. In addition, marked permanent deformation of a pressure hull might be sustained from explosive loading at 300 foot depth, for example, without further collapse of the hull occurring due to hydrostatic loading, whereas at a greater depth the same degree of deformation could result in complete hull failure due to hydrostatic loading following the explosive attack. There is considerable question, however, as to the accuracy with which such small scale models represent full scale submarines in their resistance to underwater explosive attack.2
15-15. It is apparent that there is need for further research and experimental studies in order to determine the exact behavior of non-contact underwater explosions and their effect on present and projected submarines under every conceivable condition. It is considered that such studies would be principally of value for the optimum development and employment of underwater anti-submarine explosive weapons. In addition, however, further study of hull deformation short of rupture, and shock effects, should make possible continued improvement of the strength of submarine pressure hulls under dynamic loading, increased shock resistance of machinery and vital systems, and perhaps improved basic characteristics of submarines and their operating doctrine.
15-16. The question naturally presents itself as to what hazard, if any, exists in the possibility of close underwater explosions causing detonation of torpedo warheads when loaded in torpedo tubes having their outer doors open, or of the 50 caliber, 20mm and 40mm and 3, 4 or 5-inch fixed ammunition carried topside on submarines in pressure-proof ready service cases. It is known that projectiles and torpedo warheads are generally subject to detonation under the following conditions: (a) when subjected to the roasting effect of high temperatures applied for protracted periods of time (generally 15 to 30 minutes for TNT-loaded torpedo warheads); (b) when struck by high velocity fragments; sensitivity to detonation in this latter case being dependent upon the velocity of the fragment, the temperature of the fragment,
1 Static collapsing depth of these SS285 scale models was about 870 feet. 2 David Taylor Model Basin conf. Report C-SS/S1-8; C-S81-3 of March 1947.
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the wall thickness of the warhead or projectile concerned and the sensitivity characteristics of the explosive itself; and (c), sudden and violent crushing or pinching of the container walls of dent sensitive explosives. It is believed that condition (a) can be ruled out since even should the gas bubble from a nearby detonation envelop an exposed projectile or torpedo warhead while in a late stage of its expansion, the temperature of the gases would then be relatively moderate and the heat would not be applied for a sufficient length of time to cause detonation. Should the gas bubble make contact during its early and extremely high temperature phase, the point of detonation would then be so close to the hull that destruction of the ship would doubtless in any event occur.
15-17. With regard to condition (b) above, carefully conducted tests and the combined war experience of both submarines and surface ships indicate that for all practical considerations little to no hazard exists in this respect. It has been ascertained that high velocity fragment attack upon an exposed torpedo warhead or projectile will generally not cause detonation when the fragments pass through a few feet of water (4 ft. or more). This is due to the fact that fragment velocities are decreased so rapidly upon passing through the water as to become less than the critical velocity necessary for detonation of even a relatively sensitive explosive such as Torpex. For example, it has been demonstrated in a series of tests, that the detonation of a Mk. 13 mine (675 pounds TPX) would not cause the detonation of an AN-M64 GP bomb (262 pounds TNT) even though both were suspended only four feet apart in free water.1 In this case the bomb was completely enveloped by the gas bubble from the adjacent mine detonation and was also subjected to intense fragment attack. As another example, the British submarine HMS TRIUMPH, while proceeding on the surface on 26 December 1939, struck a floating contact mine almost directly under her bow.2 The resulting detonation demolished the forward 18 feet of the hull back to the muzzle doors of the lower torpedo tubes, and caused immediate flooding of the forward torpedo room plus other damage farther aft. Although the forward lower tubes were loaded with torpedoes, no warhead detonations occurred. No information is available as to whether or not torpedoes were loaded in the two bow external torpedo tubes, which on the TRIUMPH Class are located in the superstructure about ten feet forward of and four feet above the lower nest of four tubes, and therefore presumably would have been more heavily damaged. TNT-filled torpedo warheads are difficult to detonate by fragment attack since the required critical fragment velocity is very high. Numerous cases are on record where TNT-loaded warheads on destroyers have been punctured by strafing or fragment attack from close bomb hits without themselves detonating. Submarine torpedo warheads are currently being loaded with HBX-1, an explosive having a fragment sensitivity comparable to that of TNT.
15-18. Condition (c), detonation by sudden and violent crushing or pinching of the container walls of dent sensitive explosives, appears
1 Office of Scientific Research and Development conf. Report No. 4810.
2 ONI Attaché Report No. 992 of 4 September 1940.
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to offer definite hazard to exposed torpedo warheads when loaded with a relatively sensitive explosive such as TPX. This is due to the fact that the strength of the warhead container walls may not be sufficient to prevent crushing action under close underwater explosive attack. In GATO's (SS212) action of 1 April 1943, for example, the warhead of a torpedo stowed in one of the after tubes was severely crushed by a close depth charge attack aft (Photo 15-3). The tube was flooded at the time, with the outer door closed, but apparently the pressure waves from the depth charge explosions forced the outer door open slightly and thereby admitted full pressure to the warhead. It is not known whether the explosive charge in this warhead was TNT or TPX, both types being still in use by our submarines at this period of the war. If the filler had been TPX, there is appreciable likelihood that the warhead would have detonated and caused the loss of the ship. It appears that torpedo warheads containing dent sensitive explosives should be made of somewhat greater strength than the pressure hull so that destruction of the hull can be expected before appreciable deformation of the warhead container will occur. On GATO the pressure hull adjacent to the torpedo tubes was depressed by as much as 2 inches, indicating that the hull and warhead container were of roughly equivalent strength. Since HBX-1 is understood to have a much lower dent sensitivity than TPX, the hazard with HBX-1 torpedo warheads would be appreciably less. It should be noted that, under explosive attack, substantially the full effect of the attack may reach torpedo warheads even though the outer doors are closed, due to the possibility of gasket damage or fluttering of the door under successive pressure waves.
15-19. Several instances have been reported by U.S. submarines which would seem to indicate that luminous gases, visible shock waves or smoke from close underwater detonations may have entered the interiors of the ships concerned, either through packing glands or hatches which opened momentarily. ICEFISH (SS367) reported "Got to 420 feet just as a barrage of 4 depth charges of blockbuster intensity went off on top of us. The cordite fumes from these filled the conning tower and both periscope packing glands leaked so heavily the bilges could not accommodate the water. . ."1 On KINGFISH (SS234), an EM 2/c stationed in the motor room during the depth charge attack of 23 March 1943, reported: "I was looking at the stern tube as one of the depth charge bombs burst and a ball of fire came through the tube. It came through the stern tube in the shape of a blunt streak two feet wide and extended into the boat about 3 feet. It was an instantaneous streak, flash and it was gone. . . ."2 This phenomenon was also observed by one other witness. Also on KINGFISH, it was reported that two observers saw flame shoot out of one of the after torpedo tubes coincident with a close detonation in that vicinity.3 At the same time, the air pres-
1 C.O. ICEFISH conf. ltr. SS367/A16-3/(011) of 13 November 1944 (Report of War Patrol No. One).
2 Comdt. Navy Yard, Mare Island, Supplementary Report on KINGFISH War Damage, Appendix I (Statement of Witness to Flash through Starboard Stern Tube).
3 BuOrd (Re6) memo dated 4 May 1943, (Report on Inspection of KINGFISH Damage and Interview of Ship's Officers by Dr. A. B. Focke).
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sure in the tube was reported to have increased to 130 pounds per square inch and smoke and burned explosive fumes were detected in the after torpedo room. Several after torpedo tube inner door gaskets were slightly damaged. BREAM (SS243) reported ". . . men in forward torpedo room saw blue flame spurt into the room" during depth charging.1 BLUEGILL (SS242) reported "Forward torpedo room saw flame of exploding depth charges through torpedo loading hatch when it lifted off its seat during many explosions."2 GUITARRO (SS363) reported "Blue flame showed around the periscopes and the after engine room hatch" following mass detonation of an ammunition ship 1900 yards distant.3
15-20. The descriptions of the phenomena noted above are remarkably consistent with each other, although occurring under different conditions. The odor of smoke and explosion fumes could presumably be explained only by the gas bubble having been in contact with the vessel at some time during its history. The reports connect these odors with the first events of the explosion. The connection between the odors and the gas bubble becomes confusing when it is considered that the lethal distance of the average depth charge (300 to 600 pounds of TNT or equivalent) is greater than the maximum radius of the bubble (about 20 to 25 feet for the charges cited above at periscope depth, and about 12 to 15 feet at 300 foot depth), and particularly so when it is noted that the vessels sustained no damage of great consequence. It is possible that the bubble in a later phase may actually be involved in the reports of smelling fumes, since the period of oscillation of gas bubbles from depth charge detonations is about one half of a second under typical conditions, and such an interval of time may not have been distinguished in making the report.
15-21. The observations of flame are even more confusing, since they seemingly point to contact of the hull with a gas bubble while unexploded products are still in combustion, or at least while temperatures are still high. This would almost certainly be limited to the gas bubble in its first cycle. GUITARRO's experience suggests that the gas bubble may not be involved since in her case it was impossible for the bubble of the ammunition ship explosion to have come in contact with the submarine. Shock wave phenomena emanating from explosions in air can sometimes be visually detected by observers in the same media. It is perhaps possible that some similar visual effect may be transmitted from an underwater shock wave to the atmosphere within a submarine through slack packing glands or fluttering hatches and torpedo tube doors. For example, rapid expansion of saturated air upon the passage of a shock wave will pro-
1 C.O. BREAM conf. ltr. SS243/A16-4, Serial (03-45) of 22 March 1945 (Report of War Patrol No. Five).
2 C.O. BLUEGILL conf. ltr. SS242/A16-3, Serial 039 of 25 November 1944 (Report of War Patrol No. Three).
3 C.O. GUITARRO conf. ltr. SS363/A16-3, Serial 044 of 16 November 1944 (Report of War Patrol No. Three).
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duce momentary precipitation of water vapor and this would appear as an instantaneous light haze. Air within a submarine is generally at or near saturation when running silent with the air conditioning system secured. This explanation seems to be a relatively unlikely one, but is felt to be the most reasonable hypothesis which the facts reported, assuming them to be true, will support. It is not improbable that the reports of flame may have been due to vagaries of vision. It is known, for example, that slight changes in the pressure, volume or velocity of blood in the retina will cause some people to see momentary grayish or purplish luminous clouds that sweep over the field of vision. Others may see rivers of light or a succession of scintillations that resemble fireworks.
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Photo 15-3: View showing damage sustained by torpedo warhead on GATO (SS212) as the result of a close depth charge explosion aft in her action of 1 April 1943. Torpedo was stowed in an after tube, with the tube flooded and outer door closed.
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SECTION XVI
HULL DAMAGE AND STRENGTH
16-1. A thorough search of available records indicates that throughout the entire war there were but fifteen reported cases, excluding losses, in which permanent deformation of the pressure hull was sustained by U.S. submarines as the result of non-contact underwater explosions of bombs and/or depth charges. In none of these fifteen cases was the pressure hull ruptured or torn nor is there any instance on record where a U.S. submarine has survived pressure hull rupture which occurred through war damage while the vessel was submerged.1 This is to be expected since rupture of the pressure hull of a submerged submarine should normally be lethal inasmuch as the flooding of one or more main compartments will render submerged control impossible, and the boat must then either surface, where it probably would be destroyed by enemy action,2 or must proceed to the bottom. Even assuming the bottom to be at a depth less than the collapse depth of the pressure hull and compartment bulkheads, experience shows that, under war conditions, self-salvage of the boat or ultimate escape and survival of personnel is quite unlikely.3
16-2. In three of the fifteen cases where pressure hull deformation is known to have been sustained, the boats were damaged so extensively that they were subsequently scuttled by their own crews to prevent enemy capture.4 In the other twelve cases,5 the boats successfully evaded the enemy after receiving damage and returned to base. Ten of these submarines were repaired and returned to service while two6 were scrapped.
1 (a) DRAGONET's (SS293) forward torpedo room was holed as the result of striking a reef while submerged, but she was not under attack at the time. See Section XIV for DRAGONET narrative, (b) BERGALL's (SS320) pressure hull was torn open above the waterline by an 8-inch shell hit (dud). The vessel was on the surface when struck and returned to base running surfaced for the entire distance. See brief of damage in Appendix I (13 December 1944).
2 One such possible case is the loss of ARGONAUT (APS-1) on 10 January 1943. See brief in Appendix II.
3 The loss of TANG (SS306) on 24 October 1944 is the only known instance where personnel have made underwater escapes from a U.S. submarine sunk through war action.
4 PERCH (SS176), GRENADIER (SS210), and SCULPIN (SS191). See Sections IV and VIII for narratives on loss of PERCH and GRENADIER, and Appendix II for brief on loss of SCULPIN (19 November 1943).
5 GUDGEON (SS211), 26 January 1943; KINGFISH (SS234), 23 March 1943; GATO (SS212), 1 April 1943; TUNNY (SS282), 26 August 1943; GATO (SS212), 20 December 1943; SCAMP (SS277), 7 April 1944; CREVALLE (SS291), 14 May 1944; TUNNY (SS282), 1 September 1944; SALMON (SS182), 30 October 1944; HALIBUT (SS232), 14 November 1944; REDFISH (SS395), 19 December 1944; GREENLING (SS213), 25 January 1945. See narratives in Sections V, VI, VII, IX and briefs in Appendix I.
6 SALMON (SS182) and HALIBUT (SS232)
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16-3. Since the strength of submarine hulls is naturally a subject of great interest to both operating and repair personnel, a brief discussion of the elementary design criteria of such hulls, and their probable mode of failure, has been included below. The information has been obtained from the considerable investigations conducted by the David Taylor Model Basin and this Bureau.
16-4. Weight considerations are a determining factor in submarine design since the sum of the weights of the various components of the ship, i.e., hull, propulsion machinery, armament, control gear, etc., must equal the weight of the water displaced by the intact volume of the ship when submerged. It is apparent that weight saved by the use of an efficient hull structure can be utilized for the benefit of the other components or for further increasing the strength of the pressure hull to permit a greater operating depth. Submarine pressure hulls are therefore usually made circular for as great a proportion of the length as possible. For the sake of simplicity, in the preliminary design study of a projected submarine the diameter of the pressure hull can be considered as the principal variable determining the amount of weight which will be available for the various ship components. The length of the hull is usually fixed by the arrangement study, i.e., the space requirements of armament, stores, crew, propulsion machinery sufficient to achieve the desired surface and underwater speeds, etc. The diameter and length determine the submerged buoyancy which, after subtracting the weights of the other components, determines the amount of weight that can be utilized for the hull structure and therefore the collapse depth of the vessel. In actual practice, the preliminary design phase may consist of a series of studies to determine the effect of varying length, diameter, hull form, types of propulsion plants, arrangements, etc., on such operating characteristics as speed, range, and submergence depth, in order to achieve the best compromise possible. Once the diameter of a projected submarine and its operating depth (including a reasonable factor of safety) have been decided upon, the detailed structural design of the pressure hull can proceed.
16-5. Under external pressure, the collapse strength of a transversely framed cylindrical vessel of circular cross-section is determined by the physical properties of the structural material used for the shell, the shell thickness/diameter ratio (t/D), and the unsupported length between frames/diameter ratio (L/D). By varying these factors, failure of the shell plating can be made to occur, under sufficient external pressure, in one of the following three manners: (a) by stresses in the shell reaching the yield strength of the material; (b) by instability or buckling of the shell at stresses below the yield strength of the material; and (c), by what can be considered as a combination of failure by both instability and yield. Assuming constant diameter (d) of the transverse section and adequate but not excessively heavy framing, the relation between the thickness of the shell (t) and the unsupported length between frames (L) will then determine which of the above modes of failure will govern. If the shell is relatively thick and the unsupported length between frames relatively small, the shell will not fail until the material
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is stressed to its yield strength by the combined effect of tangential and longitudinal stresses. The tangential stress resulting from radial compression (i.e., the compressive ''hoop" stress) is the determining influence in this mode of failure. The longitudinal stresses which result from end compression of the cylinder, from flexure of the entire hull as a beam, and from inward bending of the plating between frames under radial hydrostatic pressure, will have only minor influence in bringing about collapse in this case. This type of failure is analogous to the compression failure of a short, thick column. The first manifestation of failure will be the characteristic formation of a series of in and out bulges in the circumferential belt of the shell between frames (See Photo 16-1). However, if the shell is relatively thin and the unsupported length between frames is relatively large, buckling of the shell between frames similar to that just described will occur before the shell has been stressed to the yield strength of the material. In this latter case, the buckling action is called failure by "elastic instability" and collapse will occur at a much lower hydrostatic pressure than in the first case. The action is analogous to the failure by elastic instability of a long slender column. It is of interest to note that in the first type of failure the buckles form after the shell commences to yield plastically, whereas in the second case buckling starts while stresses are still in the elastic range.
16-6. Assuming adequate rigidity, the frames have considerable influence on the strength of the vessel by maintaining the original circular hull form. For a constant shell thickness and diameter, and assuming frame spacing initially of such distance that failure of the hull will occur by elastic instability, then as the frame spacing is decreased (i.e., as the L/D ratio becomes smaller), the collapsing pressure of the vessel will increase, since, although failure will still occur by elastic instability, the "hoop" stresses in the shell when failure occurs will become progressively larger and will approach the yield strength of the material. The collapsing pressure will continue to increase as the frame spacing decreases until the L/D ratio is reduced to that value at which the frames carry a sufficient portion of the load to prevent the shell from buckling until the combination of the "hoop" and longitudinal stresses in the shell material reach the yield strength. The collapsing pressure for the shell then becomes practically independent of further decrease in frame spacing. Once their spacing has been determined, the frames are designed so that they will collapse at a pressure slightly above the pressure that will cause buckling of the shell between the frames.
16-7. A sturdy column is one which will not collapse until stressed to the compressive yield point. The sturdiness of a column depends upon its slenderness ratio (L/r), where (L) is the length of the column and (r) is the least radius of gyration. Generally speaking, the sturdiness increases as the slenderness ratio decreases. Likewise, the sturdiness of a pressure vessel, assuming rigid framing, depends upon
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an analogous slenderness ratio which can be expressed in a manner corresponding to the column theory as below:
When this ratio is modified to include the physical properties of the shell material (S = yield strength, E = modulus of elasticity), it is referred to as the "thinness factor" and is expressed as:
The sturdiness of a pressure vessel increases as the thinness factor decreases. It can be seen that increasing the yield strength of the material, while holding the other factors constant, increases the thinness factor and therefore the prospect that the vessel will fail by elastic instability before the "hoop" stress in the shell due to hydrostatic loading approaches the yield point. If a light, and efficient construction is to be attained, the "hoop" stress in shell material should approach the yield stress before buckling occurs and this requires that a proper balance be achieved between t, L, and D for the yield strength of the steel selected. High strength steels, for example, require relatively close frame spacing if the full yield strength of the material is to be realized.
16-8. Circular submarine hull designs currently in use by the U.S. Navy are considered as thin shell vessels stiffened by rather closely spaced frames that are sufficiently rigid to maintain the circular form until the shell between frames starts to fail. It is intended that the various strength factors be so balanced that when the hydrostatic collapse depth is passed, the hull will commence to fail by buckling of the shell plating between frames at a "hoop" stress close to the yield strength of the steel. This buckling will first occur as a series of in and out bulges or "lobes" distributed around the circumferential belt of the shell between frames, the bulges in adjacent frame spaces being at an angle of approximately 45 degrees to each other.1 Complete failure will follow by rupture of the shell plating at some point of high stress concentration, induced by the plating tearing away from a frame and merging two or more bulges into one large bulge, bending of the frames out of their normal plane or circular shape, or by a tendency of the hull to twist and close up the frame spacing in accordion-like folds due to end pressure. High stress concentrations at hatches, or any type of stress raiser, may very possibly cause a rupture even before the bulge pattern between frames becomes evident.
1 A series of 14 distinct and separate inward bulges (1/2 lobe) should theoretically occur around the complete circumferential belt between each frame space on SS285 Class submarines.
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16-9. In the hope of attaining added safety during attack, and also to better avoid detection, the pressure hull of the SS285 Class was designed to permit a much greater depth of submergence than that of any previous submarines in the U.S. Navy. The increased strength was attained partly by increasing the thickness of the pressure hull plating and partly by use of steel of greater strength, i.e., high tensile steel rather than medium steel. In addition, H-frames were used instead of the I-frames and T-frames employed in previous designs, since H-frames, due to their wider flanges, possess greater torsional and transverse rigidity for a given sectional area and are therefore less susceptible to buckling or upsetting (Photo 16-1)1 It is interesting to note that only two submarines of this Class reported sustaining permanent pressure hull deformation as the result of underwater explosive attack, although many were subjected to close detonations of bombs and depth charges.2 No SS285 Class submarines are known to have sustained any indications of failure due to overdepth.
16-10. Near the forward and after ends of U.S. submarines, the inner circular pressure hull terminates and the outer hull becomes the pressure hull. These single hull ends conform to the lines of the submarine, gradually fairing into a shape which approaches that of an ellipse in cross section. Frames of the single hull portion are internal while those of the cylindrical double hull portion are external to the inner hull. The internal frame, together with a strip of shell acting as a flange, is designed to take the full load, and the shell, except that portion considered as the frame flange, although very heavy and capable of withstanding large loads, is considered primarily as an envelope to keep out the water. The internal frames are designed so that their neutral axis will, as nearly as possible, approximate a circle. The single ends are made slightly stronger than the circular hull to provide some protection against collapse of end structure by reason of trim angle. Past experience and tests have been the guide in progressive development of non-circular hulls rather than theoretical formulae. Several cases have occurred where the single hull ends of U.S. submarines have sustained extensive plating and moderate frame deformation
1 David Taylor Model Basin Conf. Report No. 515 of May 1943 (Hydrostatic Test of a 1/12-Scale Model Pressure-Hull Section of the SS285 Class of Submarines).
2 REDFISH (SS395), depth charged on 19 December 1944 during her second patrol and CREVALLE (SS291), depth charged on 14 May 1944 during her third patrol. See briefs of damage in Appendix I.
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under severe depth charge or bomb attack.1 No serious weaknesses were disclosed in these single hull ends, although areas of plating proved susceptible to local failure. On both TUNNY (SS282) and HALIBUT (SS232), the section of the top pressure hull plating between the forward escape trunk and the forward torpedo loading hatch was markedly depressed, whereas adjacent plating was not affected;2 also on TUNNY, the boss for the bow plane tilting gear in the overhead pressure hull of the forward torpedo room was depressed to a depth of about 2 inches, whereas adjacent plating was not affected;2 on KINGFISH, local depressions occurred in way of the shell plating for engine lubricating oil stowage tank No. 5.3
16-11. Flats bounding tanks exposed to full sea pressure, such as those of the forward and after ballast tanks on SS285 Class and previous submarines where the torpedo room decks form the tank tops, must be capable of withstanding, without excessive de-formation, the maximum pressure corresponding to the collapse depth of the other portions of the vessel. The stiffening for such flats is usually provided by an intersecting system of floors and longitudinals. The plating is divided by these floors and longitudinals into approximately square panels and the welding connecting the flat to the stiffening system makes these members integral components. The design of flats, as in the case of non-circular hulls, is based to a large extent on empirical data derived from tests and service experience. There are three cases known to the Bureau where forward or after ballast tank flats were deformed inward as the result of close bow or stern depth charge or bomb detonations (Photo 16-2).4 In none of these instances was the distortion such that any portion of the plating was torn loose from the stiffening members. In each case, the adjacent single hull plating was also deformed, and to a greater extent than the flats in two of the three cases. It is interesting to note that although TUNNY (SS282) twice sustained extensive shell deformation in her single hull ends, in way of the forward torpedo room in her action of 26 August 1943 (Section VI), and in way of the after torpedo room in her action of 1 September 1944 (Appendix I), in neither case was damage to the torpedo room flats reported.
16-12. The primary function of the main divisional bulkheads on U.S. submarines is to preserve the watertight integrity of the several compartments of the vessel in the event of damage and subsequent flooding from sea. Unlike bulkheads of surface ships, they are neither intended to serve as racking members nor are they primarily designed to support loads on decks above. These bulkheads make no contribution to the collapse strength of the hull and are not intended to take any load
1 TUNNY (SS282), 26 August 1943, Section VI, and HALIBUT (SS232), 14 November 1944, Appendix I, are excellent examples of damage to single hull ends.
2 See paragraph 6-15.
3 See paragraph 5-12.
4 KINGFISH (SS234), 23 March 1943, Section V; HALIBUT (SS232), 14 November 1944, Appendix I; and REDFISH (SS395), 19 December 1944, Appendix I.
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except in the case of flooding or where portions of the bulkheads form the boundaries of pressure tanks. Escapes were enabled from both SQUALUS (SS192) and TANG (SS306) when watertight boundaries which prevented further flooding were established at bulkheads by quick action on the part of the crews. Although in both of these instances the holding bulkheads were not subjected to pressures near the maximum for which they were designed, it is interesting to note that the doors and fittings remained substantially intact under deflection. The bulkhead on SQUALUS showed no signs of permanent set on subsequent examination although it withstood a head of about 230 feet of water for several weeks. One interesting case of bulkhead damage was that which occurred on HALIBUT (SS232) in her action of 14 November 1944, during which the forward portion of her pressure hull received severe damage as the result of close depth charge attacks. The after bulkhead of the forward torpedo room was deflected forward, both port and starboard, but only in that portion at the outer periphery which formed the junction between the inner and outer hulls (Photo 16-3).
16-13. While the factors controlling the strength of submarine hulls to withstand hydrostatic pressure are now well understood, no accepted theory exists as to the strength of a submarine pressure hull under the condition of combined hydrostatic loading and dynamic loading that occurs when a submarine is undergoing attack by explosives at a considerable depth. Experimental data now available is not sufficient to serve as a guide in the formulation of such a theory. However, new and significant information was obtained from the series of deep sea explosive tests conducted on small scale submarine models by the Underwater Explosives Research Laboratory of the Bureau of Ordnance (paragraphs 15-9 and 15-14).
16-14. The modes of failure of submarine structures under combined explosive and hydrostatic loading can be divided into two general classes as follows: (1) immediate splitting or tearing of the pressure hull due to direct action of contact or close detonations; (2) deformation of the pressure hull due to explosive loading, but without splitting or tearing occurring, followed by collapse or tearing due to hydrostatic loading on the weakened structure (if the depth is great enough). The combined effect of hydrostatic loading due to depth, and explosive loading from bomb or depth charge detonations, is greater than either alone, and the lethal distance of a given weight of explosive increases rapidly as the depth of a submarine is increased.1 TANG (SS306), TULLIBEE (SS284), ROBALO (SS273), and FLIER (SS250) are known to have been lost through destruction of a portion of their pressure hulls from close or contact detonations. As stated previously, no U.S. submarines are known to have survived war damage which breached their pressure hulls while submerged. It should be noted that the range at which a given weight of explosive will cause permanent deformation only of a submarine pressure hull is but slightly greater than the range at which the
1 See paragraph 15-14.
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same weight of explosive will cause rupture or complete failure of the hull to occur. The distance increment between the range at which permanent deformation only will occur, and that which will cause complete destruction, considerably decreases as the submergence depth of a submarine increases.
16-15. It is considered that the most serious structural hazard to a submarine from underwater detonations which are located at distances slightly greater than the limiting distance which would in any event cause splitting of the pressure hull, is the possibility of rupture or tearing occurring at a "hard spot" or discontinuity of structure which produces local areas of high stress concentration. There is hardly any portion of a submarine hull structure which is entirely free from these stress raisers, and as a consequence the hulls are vulnerable to failure at such points. Photos 16-4, 16-5 and 16-6 show typical pressure hull failures in areas of stress concentration as obtained during tests conducted by the Bureau on full scale submarine sections at the Navy Yard, Portsmouth, in 1942. The detail specifications for all recent submarines outline methods of attachment of the ends of stiffeners to the strength hulls to insure a measure of protection against dynamic loading from underwater explosions. Liners and pads are provided to protect the hulls against tearing when dented or deflected in the way of the ends of stiffener brackets. Welding is so designed that the stiffeners will pull away from the pads before the pads tear the hull plating. The design details are based on information obtained from many explosion tests, and war experience has shown that the methods are generally satisfactory. An elastic connection is less liable to sustain damage than one that is rigid and forms a hard spot. Hard spots, abrupt changes in area of members, nicks, and unsupported edges of holes are potential starting points of failure and should be avoided. Efforts are made to reduce the locked-in welding stresses both in the design and building of submarines.
16-16. The damage which occurred to SCAMP (SS277) in her action of 7 April 1944 illustrates features of both correct and incorrect detail design. The pressure hull of SCAMP broke free from several frames in way of the heaviest damage (Photo 9-8). This was obviously far less serious than the same damage accompanied by a tear in the hull plating would have been. The frames on SCAMP were I-sections. It is perhaps possible that had H-section frames been installed, as on the SS285 Class, the frames might not have broken free from the hull since inward bending of the wide faying flanges of an H-beam will absorb considerably more energy and deformation than the relatively narrow faying flanges of I-section frames. With either type of frame, however, it is preferable to employ welding of such strength that the frames will break free without tearing the pressure hull. This is insured by the welding design and is facilitated by the fact that the frame welding can only be as heavy as the flange thickness will permit, and, with present frame sections, the maximum strength of such welding is less than that of the shell plating. Undesirable designs for conditions
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of high explosive loading were illustrated by two failures which occurred on SCAMP: (1) tearing of the outer hull tank top plating at frame 79, as detailed in paragraph 9-24 and Photo 9-7; and (2), tearing of the main engine air induction line at its welded bracket supports, as detailed in paragraph 9-22 and Photo 9-5. Both of these failures were caused by high stress concentrations. SCAMP's narrative demonstrates the serious effects such apparently minor design defects may have on the survival of a submarine when attacked.
16-17. The collapse strength of a submarine circular hull is reduced markedly when there is any appreciable departure from a truly circular section. Hydrostatic tests of submarine models demonstrated that those models having even a small degree of out-of-roundness failed at pressures below that required to cause failure of more perfect models. Where the out-of-roundness was limited to a lobe length (see paragraph 16-8) between two adjacent frames, the first bulge to appear as pressure approached the failure value was almost always at this initial buckle or dent, and the bulge patterns spread out from this point. Deep sea explosion tests on SS285 Class pressure hull models conducted by the Underwater Explosives Research Laboratory demonstrated that out-of-roundness was even more detrimental to submarines under combined explosive and hydrostatic loading than under hydrostatic loading alone.1 Current specifications require that at no place shall the maximum radius of the circular hull exceed the minimum radius by more than one-half the shell plating thickness. Tests show that if this tolerance is not exceeded, no appreciable reduction in strength will result. The importance of maintaining the circularity of the pressure hull to within the above tolerance can not be overemphasized. Checks of hull circularity should be made in all cases where submarines have sustained pressure hull deformation.
16-18. Dishing of pressure hull plating between frames due to over-depth operations has occasionally occurred (SALMON Photo 7-5). While it is true that such dishing cannot be considered to have weakened the hull from the standpoint of hydrostatic loading alone, and that the submarine should be able to again safely descend to the depth at which the dishing originally occurred, the resistance of the dished hull to bending stresses and explosive loading is definitely decreased. Once a dish has formed, the plate in the vicinity has absorbed energy which it cannot again absorb and is therefore more susceptible to failure under explosive attack. In all cases where marked pressure hull dishing has occurred, whether due to hydrostatic pressure or explosive attack, the original geometry of the structure should be restored and new plating is recommended.
16-19. Expedients should not be adopted which will in any way weaken submarine hulls or introduce areas of doubtful structural strength. The welding of pressure hull structure back into place falls in the category of restrained welding in which there are always locked-in stresses.
1 OSRD conf. Report No. 5417.
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These stresses may result in the immediate formation of cracks (which for grooved "tee" joints may not be discernible by magna-fluxing or other methods of inspection), or in the failure of the structure under loads considerably below the full strength of the material. Certain alterations and war damage repairs occasionally leave no other course than to cut the hull plating and structure and to install replacement material. Patches, except when worked flush with plating in a cut-out section, are stress raisers, and because of the hard spots introduced are potential danger points even though perfectly welded. The original geometry of the hull should be restored in all cases. Any attachments such as padeyes, cleats, etc. are stress raisers and should be avoided. Even slight nicks, such as those caused by striking a welding arc, will tend to produce notch effects. Experience during the war has demonstrated that the utmost care must be taken on submarine pressure hull repairs and that X-ray or radiographic examinations must be conducted if defects are to be avoided. It is also extremely important to check the physical and chemical properties of the replacement material when any doubt exists as to its meeting the required specifications for the hull area concerned.
16-20. The Bureau has issued rigid instructions on the methods to be employed in cutting and welding of submarine pressure hull structures and structural fittings subject to deep submergence pressure. The reader is invited to refer to the following letters for further information: BuShips conf. ltr. SS/S11-1(515-692) of 8 May 1944; BuShips conf. ltr. SS/S29-6(515) of 15 May 1944; and BuShips conf. ltr. SS/S11-1(515) of 2 April 1945.
16-21. The marked improvement of welded construction over riveted construction in resistance to war damage has been repeatedly demonstrated in both surface vessels and submarines. There is no reported instance where welds in U.S. submarine pressure hulls have failed as the result of war damage. This fact of course does not preclude the possibility of such failures having occurred, since the results would very likely have proven fatal to the submarine concerned. That welding has proved so satisfactory on our submarines is attributable to the constant emphasis placed by the U.S. Navy on improving welding methods and materials, adequate training of welders, qualified supervision, frequent inspection, and the correct design of ship welding details. Experience has demonstrated the importance of proper welding sequence in the control of shrinkage, distortion, locked-in stresses and cracking during construction. The importance of good workmanship cannot be overemphasized. Poor workmanship engenders fracture, since failure may originate at a small notch such as is occasioned by peened-over cracks, undercut welds, porosity and inclusions in the weld, improper joint preparation resulting in incomplete penetration which leaves voids at the center of the joint, incomplete backside root chipping on grooved joints, etc. The importance of maintaining the welding standards set forth by the Bureau for production and repair welds for submarine pressure hulls cannot be overemphasized.
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16-22. It is interesting to note that there are several submarines which have been quite heavily depth charged and on which laminated pressure hull plates were subsequently found. In theory, laminated plates involve a loss in strength. However, this assumes the lamination to be complete; that is, that there is a free plane of cleavage which would permit the separated plates to move freely relative to each other. In practice, the laminations are not free planes but are irregular and partially fused surfaces. It is believed that such surfaces will act in shear substantially as if joined and that no important loss in strength will result. When encountered, they should not be regarded as cause for alarm. Nevertheless, laminated plates should never be worked into submarine structure, and when found during construction or repair should be removed if possible.1
16-23. War experience indicates that riveted and bolted access plates as fitted in submarine pressure hulls have been generally satisfactory in strength compared with other portions of the pressure hull, but that when extreme shell deformation occurs, the joints of such plates tend to open and may develop serious leakage. For example, on GRENADIER (SS210)2 during the action leading to her loss on 22 April 1943, the riveted plate over the maneuvering room tore partially free from adjacent plating when the pressure hull in that area was damaged. This allowed a stream of sea water to cascade upon the main control cubicle beneath and was one of the factors which caused loss of propulsion. Riveted plates, however, appear to withstand moderate deformation without tearing or developing excessive leakage. On both SALMON (SS182) and KINGFISH (SS234), the riveted plates in way of the areas of pressure hull damage were themselves considerably deformed but remained tight or nearly so.3 However, on KINGFISH, several riveted keystone frame joints started to separate (Photo 5-2).
16-24. Riveted and bolted plates, when properly designed and fitted, are not structurally weak from the standpoint of normal hydrostatic loading. However, double butt-straps act to create hard spots and thus may weaken adjoining structure rather than in themselves constituting a weakness, and riveted construction is not fundamentally desirable from the standpoint of watertightness when subjected to large deformations. In addition, the reinstallation of riveted plates, once removed, usually involves considerable time and expense. New butt-straps and plates are frequently required; oversize holes must be welded
1 BuShips ltr. SS283/S11(515) of 4 November 1944.
2 See GRENADIER narrative, Section VIII.
3 See KINGFISH narrative, Section V, and SALMON narrative, Section VII.
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up and redrilled; caulking edges may have to be built up by welding; faying surfaces on adjacent pressure hull structure occasionally develop ripples; obtaining metal to metal contact along the longitudinal seams is often a long and arduous process; and reriveting may be substandard. It now appears possible that the use of riveted portable plates may be discontinued in favor of welded plates on both new construction and submarines in service. However, it is intended that bolted access plates will be retained in those locations where repeated removal may be necessary, such as for battery and parts replacement.
16-25. The rupture of the forward torpedo room 37.5 pound HTS pressure hull plating on DRAGONET, as the result of striking a rocky promontory while submerged, is an excellent example of the type of failure to be expected when heavy concentrated loading is applied to restrained plating panels. In DRAGONET's case, it is quite likely that the force of grounding was sufficient to cause the shell to fracture in any event. This is indicated by the fact that one of the frames supporting the plating also broke. However, the plating was greatly restrained in the area of rupture by extremely strong and rigid internal frames, spaced on 24 inch centers, which acted to prevent vertical movement and tended to increase the likelihood of early fracture. The capacity of restrained material to absorb energy is reduced markedly since the ability of the material to flow plastically is less than that of unrestrained plating. The fact that DRAGONET was operating in water at a temperature about 29°F.1 may have been a contributing factor in the failure of the pressure hull plating. It has been definitely established that low temperature greatly reduces the ability of both MS and HTS to absorb energy. The temperature below which the capacity of steel to absorb energy decreases rapidly is generally referred to as the transition temperature. Below the transition temperature, fractures show a brittle, crystalline surface in contrast to the fibrous type associated with the same steel at higher temperatures. The few test results available seem to show only a negligible change in yield strength as the temperature is lowered. Therefore, under static or slowly applied loads, it is not considered that appreciable change in strength is to be expected. Temperature effects are reflected in impact and notch tests rather than in static tests. Since the transition temperature has been found by actual tests to vary from -20°F. to well over 100°F. with different samples of MS and HTS, although all of the samples satisfied the specifications, it is impossible without actually testing the material in the region of the failure on DRAGONET to determine its transition temperature. The appearance of the fractures on DRAGONET suggests that low temperature may have been a factor in the plating failure, although as previously stated, the force of grounding was no doubt sufficient to have caused the failure. It should be noted that the average transition temperature of high tensile steels, as in the pressure hulls of SS285 Class and subsequent submarines, (less SS361-364), is considerably lower than the average for the
1 Temperature measured at engine injection (saltwater).
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medium steels used in previous submarine classes, and therefore the use of HTS material can be considered as a definite improvement over MS in this respect.
16-26. Ballistic protection on U.S. submarines has been limited to the installation of 20 and 30 pound STS for the protection of bridge personnel and 40 pound STS for ready service ammunition. In addition on SS285 Class submarines the entire conning towers, including the ellipsoidal end bulkheads, were fabricated from 40 pound STS for this purpose. Ballistic protection was authorized in April 1943 for all fleet type submarines subsequent to SS197 when the need for shielding the vulnerable bridge, conning tower and ready service ammunition was demonstrated by several aircraft strafing and small caliber surface engagements, such as GROWLER's action of 7 February 1943.1 Generally speaking, and disregarding a possible high velocity of approach of the firing weapon, 20 pound STS will provide protection against normal impact of .50 caliber projectiles fired from a range of 1000 yards and 40 pound STS will provide similar protection at 100 yards. In at least two instances the STS plating on our submarines was penetrated.2 With the exception of the conning tower hatch on GROWLER, there were no instances where either conning towers or pressure hulls were penetrated by small caliber enemy projectiles. This is attributable to the low incidence of such attacks rather than to the meager protection afforded by the small amount of STS plating provided for our submarines. The design problem in ballistic protection of submarines is one of calculated risk in any event since weight and stability considerations will not permit extensive use of STS in thicknesses sufficient to insure defeat of small caliber projectiles fired at close range.
16-27. The structural design of modern submarines is the result of evolution over a period of many years. Research, particularly with full scale caissons, initiated by the Bureau and accomplished mainly at Portsmouth, N.H., and model tests and theoretical analyses by the David Taylor Model Basin have contributed greatly to present knowledge and design practices. While marked advances have been achieved in the past several years, further improvements appear definitely possible. The elimination, where possible, of hard spots and potential points of stress concentration in pressure hulls is a matter which should be borne in mind by the operating personnel in establishing requirements and features which require pressure hull penetration. Hull openings should be held to an absolute minimum. Theoretical investigations and further controlled testing of models and full scale vessels are required to widen the field of knowledge on the behavior of submarines under explosive attack. Steels are currently under development which it is hoped will combine the desirable qualities of high yield strength; high ductility; notch toughness; increased energy absorption characteristics at the high strain rate conditions which result from explosive loading; weldability; and low transition temperatures. Submarine hull designs for operation at depths of as much as 1000 feet may then become feasible within the percentage of submarine total weight which can be devoted to hull structure.
1 See GROWLER narrative, Section XIII.
2 See briefs of damage in Appendix I for SKATE (SS305), 6 October 1943; and POGY (SS266), 19 April 1945.
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Photo 16-1: View of Model No. 107 after hydrostatic test at U.S. Navy Experimental Model Basin. Note typical example of bulge formation in shell and failure of frame having insufficient rigidity. The need for wider frame flanges is clearly indicated, such as provided in the H-frame sections used on SS285 Class submarines.
Photo 16-2: HALIBUT (SS232). View showing deformation which occurred to MBT No. 1 tank top flat in forward torpedo room of HALIBUT (SS232) as a result of her action of 14 November 1944. Washboard effect on port side is shown.
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Photo 16-3: HALIBUT (SS232). View showing buckled area of after bulkhead of forward torpedo room on HALIBUT (SS232) as a result of her action of 14 November 1944. Bulkhead was deflected forward in peripheral strip between the junction of the inner and outer hulls, from about 40° below top center to about 90° from top center, both port and starboard.
Photo 16-4: Typical example of tearing of inner shell at stress concentration formed by incorrect junction of bulkhead stiffener as obtained by explosive tests on a full scale submarine partial length section at the Navy Yard, Portsmouth in 1942.
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Photos 16-5 and 16-6. Typical failures of inner hull as obtained by explosive tests on a full scale submarine partial length section at the Navy Yard, Portsmouth in 1942. Above: tear in pressure hull plating at tank top margin plate. Note that I-frames are torn from pressure hull. Below: tear in pressure hull at junction of I-frame with tank top margin plate.
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SECTION XVII
STABILITY, BUOYANCY AND FLOODING
17-1. The stability, buoyancy and trim of a submarine present a unique problem, involving three main phases: (1) operation as a surface vessel, (2) the period of submergence or surfacing and (3) underwater operation. While operating on the surface, the stability and trim of a submarine and calculations thereof are the same as for an ordinary surface ship. The calculation of stability for the submerging period is based on the same principles as for the surfaced condition but is considerably more complicated since arbitrary assumptions must be made as to the rate of flooding of various tanks, the angle of trim while the boat is diving, etc. Calculation of stability in the fully submerged condition is a very simple matter since both the transverse and longitudinal metacenters move to the center of buoyancy. The metacentric height or GM, uncorrected for free surface, is then measured both transversely and longitudinally by the vertical distance between the center of gravity and center of buoyancy. Balance calculations for weight and buoyancy changes in the submerged condition involve only weight and moment computations and are familiar to all submarine officers.
17-2. War experience has repeatedly demonstrated that changes in stability and weight and buoyancy distribution on submarines will frequently be caused as a direct or indirect consequence of damage and that where such changes are relatively large, ship control submerged may be lost or excessive list and trim angles may result on surfacing. In several instances our submarines have been subjected to serious military hazard following damage sustained while submerged due to inability to retain depth control, forcing bottoming or surfacing, and in at least one instance an excessive list assumed by a U.S. submarine upon surfacing after damage would probably have caused her loss had the enemy been more alert (paragraph 17-4).
17-3. DRAGONET, SALMON and SCAMP are among those submarines which assumed large lists upon surfacing after receiving damage.1 In each of these instances, the lists were caused by unsymmetrical liquid loading in external tanks. DRAGONET was reported to have assumed approximately 15 degrees port list due to inability to expel water more than a few feet below the tops of two ruptured port main ballast tanks, a fact unknown to her at the time the remainder of the ballast tanks were blown dry on surfacing. In DRAGONET's case, the list caused by the heeling moment of the two partially flooded port tanks was also slightly aggravated by the free surface effect of the water in the flooded forward torpedo room. However, calculations indicate that the reduction in metacentric height resulting from the free surface and added weight of the water in the forward torpedo room, considering the water level to have been approximately two feet above the forward torpedo room flat, was only about 0.18 foot. This was a minor reduction compared with
1 See Sections VII, IX and XIV for narratives of SALMON, SCAMP and DRAGONET.
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DRAGONET's total probable GM before damage of about 1.50 feet,1 and caused the list to increase by only about one degree. Calculations also indicate that the list was probably of the order of 10 degrees rather than the reported 15 degrees. SCAMP assumed about 17 degrees port list upon surfacing, due to inability to expel water from two port main ballast tanks and the displacement of fuel oil in one port fuel ballast tank with heavier sea water through a rupture in the tank top plating. SALMON assumed about 15 degrees starboard list on first surfacing, due to leaking starboard ballast tank master vent valves and the displacement of fuel oil in one starboard fuel ballast tank with sea water through a damaged riser. In both of these latter cases, the lists were no doubt increased to a minor extent by loss of GM due to the free surface effect of the sea water which accumulated in internal compartments from various sources' of leakage.
17-4. It should generally be expected that a submarine which sustains damage to external tanks, risers, master vent valves or the low pressure blow system to individual tanks will almost invariably assume a large list upon first surfacing. This will occur primarily because the extent and nature of such external damage will not be known while still submerged and will manifest itself only when the ship actually does list upon breaking the surface or after following normal tank blowing procedure. Large lists assumed upon surfacing should not normally be dangerous since rapid compensation can of course be made either by venting ballast tanks on the high side or by selective blowing of ballast tanks on the low side. It has been demonstrated on several occasions that submarines can quickly get underway on their surface Diesel propulsion plants even with lists as high as 15 degrees. SCAMP and DRAGONET are two such examples However, should a large list persist on a submarine after surfacing, and if the submarine were unable to resubmerge if attacked during this period, due to damage, low air reservoirs or depleted batteries, gun operations and ship handling would certainly be hampered, if not impossible. For example, SALMON would very probably have been destroyed after surfacing in her action of 30 October 1944 had the enemy escorts not delayed their attack until the ship's force had taken damage control measures and successfully righted the boat.
17-5. Calculations made for SS285 Class submarines show that a boat which is initially in normal diving trim will assume a 45 degree list if all main ballast and fuel ballast tanks on one side only are completely flooded to the tank tops while the corresponding tanks on the opposite side remain dry. This might be considered to represent the maximum possible listing moment for a surfaced submarine. Calculations have also been made to determine what angle of heel might result in the hypothetical case occurring if all main ballast tanks on one side only (not including fuel ballast tanks) were blown completely dry while submerged. The boat would then surface rapidly, of course, and while rising would steady at a list of about 70 degrees, assuming the boat rises through a sufficient distance for equilibrium conditions to occur before surfacing. On surfacing, the list would be sharply reduced to about 33 degrees since the introduction of water plane area greatly increases the
1 Condition VII-B, Emergency Diving Trim, Revised Inclining Experiment Data for DRAGONET.
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metacentric height (note that in this case only 33 degrees list results after surfacing rather than the 45 degrees calculated for the case above, since the fuel ballast tanks on both sides are considered to remain flooded).
17-6. The freeboard and reserve buoyancy of U.S. submarines now in service are sufficient even in emergency diving trim condition to permit several main ballast tanks to remain free flooding for list control, when necessary. However, if a large number of ballast tank master vent valves or risers are damaged, a submarine may then experience difficulty after surfacing in blowing up far enough to achieve satisfactory seaworthiness. For example, SALMON remained just barely awash for several minutes after surfacing due to loss of tank air through leaking master vent valves and was not able to blow up until the emergency vent valves were closed. This delay, in addition to her large list, hampered damage control efforts and gun operations.
17-7. While returning to base with her forward torpedo room partially flooded, DRAGONET reported reaching a roll of 63 degrees from upright to one side as measured by the control room inclinometer.1 At the time this occurred, heavy quartering seas and winds of gale force were being encountered. There are many other similar cases on record where submarines have reported extreme rolls. For example, SNAPPER (SS185) on her eighth war patrol and SEADRAGON (SS194) on her shakedown cruise after commissioning reported rolls reaching 45 degrees or more at times. Also, while operating off Newfoundland on 17 November 1946, DOGFISH (SS350) and SABLEFISH (SS303) reported maximum rolls from upright to one side of 52 degrees and 63 degrees, respectively, and average rolls from upright to one side of 35 degrees and 20 degrees, respectively. In all of these five cases the rolls were measured by inclinometer. It should be noted that this type of instrument is not accurate for recording large angles of roll and will in such cases indicate somewhat greater angles than actually occur. The circumstances attendant at the time the extreme rolls occurred were quite similar in each case: high wind velocities and heavy quartering seas. The periods of roll were long and the vessels seemed to "hang" at the end of the large angle rolls before returning to upright. In three of the five cases, water was shipped through the outboard induction valves and conning tower hatches. SABLEFISH reported that on her 63 degree roll it was necessary to blow ballast tanks on the low side with high pressure air in order to right the ship. DRAGONET reported that on her 63 degree roll it was necessary to swing the ship's heading through 105 degrees before the vessel slowly commenced to right herself and then steadied at about 20 degrees list. With the exception of DRAGONET, all of the above vessels are believed to have been in emergency diving trim condition.
17-8. As nearly as can be determined, SNAPPER and SEADRAGON each had a GM of approximately 1.00 foot and DRAGONET, DOGFISH and SABLEFISH each had a GM of 1.25 feet or larger. As mentioned previously, the loss in stability on DRAGONET due to the flooded forward torpedo room was minor, having the effect of reducing her GM from about
1 See paragraph 14-18.
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1.50 feet to 1.32 feet. These values of GM are more than sufficient to assure a range of stability considerably beyond 90 degrees and it is difficult to explain the tendency of the submarines cited above to "hang" at extreme angles. This "hanging" behavior is similar to that which is often reported by destroyers and minesweepers, or occasionally even larger surface vessels, under identical conditions, i.e., heavy quartering seas. The extreme rolls evidently occur as the vessels roll away from the crests of waves which are momentarily in synchronism. All vessels are subject to this action in a seaway under the right conditions. The extreme example is the broaching of landing craft in a surf. The smaller the vessel, the larger the part that must be played by seamanship to avert disaster. On a submarine, the tendency to "hang" under certain wave and wind conditions is probably aggravated by the fact that the tank tops and part of the superstructure deck will be submerged at large angles of roll, these surfaces tending to act as a plane to hold the submarine at the extreme angle of roll while it is displaced sideways due to the dynamic action of the waves.
17-9. Another factor which may contribute to the tendency to "hang" is that at large angles of roll it is possible for a submarine to spill air from ballast tanks on the low side and take on water through the flood openings, with resultant increase in heeling moment. A study made in 1942, taking into account the loss of air and consequently the partial flooding of low side main ballast tanks, indicated that statically the effect on stability was maximum between 50 degrees and 60 degrees of heel but was only a minor consideration, the loss of righting arm being less than 0.10 feet. This study also indicated that the statical stability improved beyond 60 or 70 degrees due to the addition of low weight by partial flooding of the low side tanks. The additional heeling effect of such weight would be large, of course, and tank blowing may be required in order to again right the ship. Tank blowing will only partially remove the water in the low tanks at extreme angles but should have some beneficial effect and is probably the correct course of action to take when such a case is believed to exist. It should also be noted that when air spillage occurs from low side tanks, the submarine upon righting itself will not return to the vertical but will assume a list in the direction of the low side tanks, due to the added water in those tanks, and tank blowing will then become necessary to reach the fully upright condition. Whether "hanging" at an excessive angle is due only to the synchronism of dynamic wind and sea forces, or whether progressive loss of tank air with increasing roll angle contributes appreciably to the "hanging" tendency, is not clear at present. Rolling, heaving and pitching, accompanied by heavy seas, will result in variation in head over the tank flood openings and will tend to cause loss of tank air, allowing partial flooding which will in turn reduce stability due to increased free surface effects.
17-10. Although submarines have a very poor hull form for surface transverse dynamic stability, nearly circular in cross section with very little freeboard and extreme tumblehome, the possibility of capsizing
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through loss of stability is remote. They have a positive righting moment over a wider range than most ships due to a lower center of gravity and have a smaller area exposed to the force of the wind. Submarines now in service have a range of stability beyond 90 degrees and, in addition, the hull is kept more completely closed in normal operation than in other types of vessels, the conning tower hatch and engine air induction outboard valve being the only openings. The criterion of surface stability in current use for modern fleet type submarines is that the GM in normal diving trim condition shall not be less than 1.25 feet. This figure was decided upon as a result of Bureau studies of wind heeling moments combined with synchronous rolling, and the curves of righting moments of fleet type submarines. It results in righting arms throughout the range of stability which provide a considerable margin of safety over those of SNAPPER at the time of her reported heavy rolling.
17-11. When submerging or surfacing, submarines pass through a period of low metacentric height. This condition occurs when the moment of inertia of the reduced waterplane reaches a low value concurrently with free surface effects due to partially filled ballast tanks. In modern double-hull submarines, this point of minimum GM occurs when the ballast tanks are about 70 to 80 per cent full. The detail specifications for these vessels require a minimum GM of 3 inches when submerging or surfacing. However, even with slightly negative GM when trimming down, the righting moment soon becomes positive as angle of heel increases and no real danger exists for the vessel. In addition, the condition of minimum stability is transitory, existing for probably less than a second during a normal dive.
17-12. Damaged stability and flooding studies have been made for submarines as for other combatant vessels. The amount of flooding a submarine can sustain and still operate submerged is limited at most to the relatively small capacity of the variable ballast, safety and negative tanks plus a small additional amount which can be compensated for by use of the diving planes and angles on the boat at high submerged speeds. Usually the amount of flooding which can occur while submerged without causing loss of depth control will be much less than the capacity of the above tanks since any longitudinal moments introduced by the flooding must also be balanced by the use of the same tanks, assuming that diving planes and angles on the boat are not used for moment compensation. For surface conditions, however, a submarine can absorb a considerable amount of flooding of internal compartments and tanks before upending or capsizing of the vessel will occur, particularly when the flooding occurs in amidships compartments and the submarine is in normal rather than emergency diving trim, i.e. when the fuel ballast tanks are empty.
17-13. The table below presents several hypothetical cases of flooding for SS285 Class submarines and the resulting effects
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on transverse stability and longitudinal trim when surfaced. The calculations were made for both the normal and emergency diving trim conditions. The submarine is considered to upend when the longitudinal moment tending to trim the ship after flooding remains greater than the opposing longitudinal moment of buoyancy until a near vertical position is reached. The initial transverse GM in normal diving trim was taken as 1.63 feet and in emergency diving trim as 1.59 feet, both figures being considerably greater than corresponding values for SS285 Class submarines now in service. Therefore, the figures given for lists resulting from off-center flooding are somewhat lower than would actually be the case for SS285 Class submarines in service.
Spaces Flooded |
Normal Diving Trim |
Emergency2 Diving Trim |
||
Trim on Boat |
Loss in |
Trim on Boat |
Loss in |
|
Forward Torpedo Room |
4'- 4" By Bow |
0.43' |
6'-11'' By Bow |
0.61' |
Forward Torpedo Room and MBT No. 1 |
7'-11" By Bow |
0.17' |
Ship upends |
- - |
Forward Torpedo Room and For'd Battery Comp't. |
Ship upends |
- - |
Ship upends |
- - |
For'd Battery Comp't. |
6'-8" By Bow |
0.38' |
Ship upends |
- - |
Control Room |
2'-7" By Bow |
0.59' |
Ship upends |
- - |
After Battery Comp't. For'd Engine Room |
1'-9" By Stern |
0.77' |
1'-7'' By Stern |
1.26' |
For'd Engine Room |
5'-8" By Stern |
1.04' |
Ship upends |
- - |
After Engine Room |
7'-1" By Stern |
1.01' |
Ship upends |
- - |
After Torpedo Room |
4'-3" By Stern |
0.56' |
4'-9" By Stern |
0.78' |
After Torpedo Room |
6'-6" By Stem |
0.77' |
9'-0" By Stern |
0.77' |
1 Assuming FBT No. 5A full of sea water and FBT No. 5B full of oil.
2 Now called Maximum Diving Trim
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The above table emphasizes the marked increase in ability of a surfaced submarine to absorb flooding when in normal diving trim as compared with emergency diving trim, due to the additional freeboard and reserve buoyancy of the lighter load condition. The extreme susceptibility of a damaged submarine to upend through reduction of longitudinal stability should also be noted. A submarine will usually be lost by upending, rather than by capsizing or bodily sinkage. These studies indicate that recent types of submarines, while surfaced and in emergency diving trim, i.e., in usual wartime surface condition, can probably survive the flooding of one major compartment and adjacent tanks with the possible exception of flooding of the forward torpedo room. In the latter case, blowing the bow buoyancy tank, if such remains possible after damage, should assure that upending will not result.
17-14. Also to be considered as a possible damaged condition is the flooding of the conning tower while submerged combined with the damage control measure of blowing the safety tank to maintain neutral buoyancy submerged. For modern submarines, the loss of GM will be only about 0.13 feet when submerged, and 0.18 feet after surfacing. In either case, this slight decrease in GM will not have a serious effect on the ship. It should be noted that the capacity of the safety tank is purposely designed to be slightly greater than that of the conning tower so that it can provide a rapid means of compensating for a flooded conning tower.
17-15. The longitudinal GM of a completely submerged submarine is very small as compared to the surfaced condition, being essentially equal to, or, considering free surface effect, slightly less than the transverse GM, both being a function of the distance between the center of gravity and the center of buoyancy. Consequently, relatively small changes in longitudinal moment will have relatively large effect on trim and therefore on the ability to maintain satisfactory ship control when submerged. In addition, changes in total weight will place a submarine in a condition of either positive or negative buoyancy and will affect depth control. When considering the ability of submerged submarines to sustain war damage, it is apparent that this sensitivity to small changes in moment and weight constitutes one of their most vulnerable aspects.
17-16. The flooding of a submarine major compartment when submerged is a serious matter. If the damaged compartment is at either end of a submarine, and if flooding is rapid, blowing of all ballast tanks to surface would probably result in serious loss of air and in upending. Under such conditions the pressure in the tanks at the high end is less than in the low end and the blowing would therefore unwater the tankage at the high end first and increase the trim angle to such an extent that the air would be spilled out of the flood openings and blowing would become comparatively ineffective. It would be far better to first blow the tankage at the low end and decrease the trim angle before unwatering the tankage at the other end. In the case of SQUALUS, it is believed that had only the after tanks been blown at first, the ship might have been surfaced.
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If a submarine settles on the bottom after flooding a major compartment, and assuming the bottom at a depth less than the designed collapse depth of the hull or of the watertight compartment bulkhead, various methods of self-salvage may be attempted. The first and most logical method is, of course, to dewater the flooded compartment by use of the internal salvage air system, as was successfully accomplished in DRAGONET's case.1 If, for some reason, dewatering of the flooded compartment is not feasible, then it is still possible to surface the submarine, without upending, by calculating moments and blowing only those tanks which will provide both a slight margin of reserve buoyancy and an overall longitudinal moment balance such that reasonable trim control can be maintained while rising, either by use of propulsion and the diving planes or by such means as shifting men and pumping, blowing or flooding forward and after variable tanks. In the case of a flooded end compartment, or where more than one compartment is flooded, normal fuel oil tanks should be considered for blowing as well as main ballast, fuel ballast and variable tanks. Blowing should progress from the damaged end. After surfacing, certain additional tanks may then be safely blown to provide additional freeboard and reserve buoyancy since the longitudinal GM will increase tremendously when water plane area is once established.
17-17. An interesting example of flooding in amidships compartments is the experience of CREVALLE (SS291) during her fifth war patrol. On 11 September 1944 CREVALLE surfaced with her ballast tank vents unintentionally still open and the bridge was manned. Fifteen seconds later the ship took a large down angle and resubmerged with the upper and lower conning tower hatches still open. The ship was making standard speed on battery propulsion at this time and as she submerged the ahead motion accelerated her descent and the down angle increased rapidly. Water poured into the conning tower and thence to the control room and pump room. The forward and after bulkhead doors of the control room were quickly closed and prevented flooding forward and aft. At 150 feet the upper hatch seated but by this time the water in the conning tower had reached armpit depth, the pump room was completely flooded and the control room was flooded above the door to the forward battery compartment (at the large down angle). At about this time, full speed astern was ordered by a quick thinking MoMM 1/c who had tried in vain to contact the control room and conning tower and then telephoned the maneuvering room. With propulsion reversed, descent was checked at 190 feet with a down angle of about 42 degrees. The ship then surfaced, backing full all the way. Since all electrical equipment in the conning tower, control room and pump room was grounded out, CREVALLE was forced
17-18. In over twenty-five instances during World War II, U.S. submarines suffered marked loss of ability to retain depth control after sustaining damage from enemy action while operating submerged. In most of these cases, loss of control was only temporary and had no serious consequences. In several instances, however, loss of depth
1 See Section XIV for DRAGONET narrative.
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control was prolonged or permanent and resulted in oscillations over a wide range of depths, broaching, bottoming, or forced early surfacing with consequent increase in hazard.
17-19. Derangements which prevented use of either or both the bow and stern planes for short periods of time were responsible for most of the cases of temporary loss of depth control, although added weight due to relatively minor flooding was sometimes an additional or the sole factor involved. The instances in which serious or prolonged loss of depth control was experienced were for the most part caused by the additive effect of several of the following factors: flooding of engine air induction and ship's supply ventilation systems; flooding of sanitary, trim and auxiliary tanks; relatively large intake of water into one or more compartments through various sources of leakage; loss of propulsion power; temporary or permanent derangement of bow and stern planes; and displacement of fuel oil with heavier sea water in damaged external fuel tanks. The suddenness with which damage occurred was often a contributory cause of loss of depth control. For example, rapid flooding of an induction system or sudden disabling of diving planes when set on large rise or dive angles frequently resulted in a boat assuming a considerable angle or large change in depth before corrective measures could be taken. In such cases restoration of control therefore became more difficult. The outflow of water ahead of the expanding gas bubbles of close underwater detonations in some cases also forced submarines to assume large angles of inclination or changes in depth (See paragraph 15-8).
17-20. The following instances of loss of depth control are particularly interesting and serve to illustrate typical situations which submarine officers may expect to occur following war damage: KINGFISH (SS234), Section V; TUNNY (SS282), Section VI; SALMON (SS182), Section VII; SCAMP (SS277), Section DC; SARGO (SS188), 4 March 1942, Appendix I; JACK (SS259), 26 June 1943, Appendix I; GURNARD (SS254), 6 July 1943, Appendix I; ALBACORE (SS218), 10 November 1943, Appendix I; TINOSA (SS283), 22 November 1943, Appendix I; BLUEGILL (SS242), 22 May 1944, Appendix I; SAILFISH (SS192), 4 November 1944, Appendix I; and HAWKBILL (SS366), 18 July 1945, Appendix I. The methods which were employed to regain depth control varied with the circumstances of each case. Weight compensation by flooding, venting, pumping or blowing variable, safety and negative tanks was resorted to whenever the tactical situation permitted. With extreme weight and trim changes, submarines were forced to blow ballast tanks or back with both propulsion shafts in order to check downward descent. After becoming heavy overall as a result of damage, several submarines managed to retain fairly satisfactory depth control by resorting to fast speeds ahead at large up angles. Two such examples are the experiences of SCULPIN (SS191) on 28 September 1942 and WHALE (SS239) on 30 October 1942, briefs of these actions being contained in Appendix I. It should be noted that once a submarine becomes heavy and has to use pumps, air or high speed to maintain depth control, the resulting noise increases the possibility of detection by enemy vessels using sonic listening gear.
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17-21. The maximum extent of flooding which a submarine can sustain and still operate submerged depends on the ships ballasting, condition of loading, location of flooding and ability to maintain depth control by use of planes, "bubbles" in tanks, and angles on the boat at high speeds. Flooding introduces added weight plus a trimming moment, both of which must be counteracted if depth control is to be retained. Weights added in amidships areas are obviously easier to compensate with the means available than weights added either forward or aft since the safety tank, which is amidships, can be blown, the resultant of the lift forces obtained by putting an up angle on a submarine at ahead speeds is exerted amidships, and the trimming moment introduced by an amidships weight is much less than an equivalent weight added forward or aft. Calculations based on SS475 Class model tests indicate that an added weight amidships of at least 50,000 pounds can be compensated by proceeding at an ahead speed of six knots with an up angle of 20 degrees on the boat.1
17-22. Several interesting tests were made on ENTEMEDOR (SS340) during April 1946 to determine how quickly the descent or rise of a heavy or light submarine could be stopped when not under propulsion.2 The submarine was first balanced dead in the water. Then, with the boat about 5000 pounds light or heavy, and allowing sufficient time for the limiting velocity of rise or descent to be reached, it was found that in every case the vertical motion could be stopped in from 10 to 20 feet of travel by cancelling the 5000-pound force and adding 5000 pounds in the direction opposite to the motion. A test was also conducted during this same period to determine the hull angle required on ENTEMEDOR to counteract the effect of the bow planes at various angles so that depth control could be maintained with the stern planes alone. At speed 6.4 knots and with neutral buoyancy, it was found that if the bow planes were locked on 25 degrees rise angle, a 5 degree down angle was required on the boat to maintain constant depth. With the bow planes locked at 25 degrees dive angle, a 2.5 degree up angle on the hull was required. Since there are many war damage cases where bow planes have been temporarily or permanently disabled, such as occurred on TUNNY (Section VI), it is interesting to note that even with the bow planes locked on hard rise or dive angles the effect on depth control is not serious provided the stern planes and propulsion remain available.
17-23. As the safety tank is a pressure tank located near the center of balance and has a capacity of about 20 tons which can be quickly blown with high pressure air, it is ideally suited for rapid compensation of a submarine which suddenly becomes heavy overall due to damage. Upon recommendation by ComSubPac in May 1943, the installation of liquidometer gauges in the safety tank of all fleet type submarines was authorized to permit finer control when necessary to blow the safety tank partially and quickly, and to afford a means of avoiding the release of an air bubble through over-blowing if ever necessary to blow the safety dry during evasion maneuvers.3 The inboard vent lines from this tank were also cross-connected and led into the control room to permit operation at that location.4
1 Experimental Towing Tank conf. Report No. 309 of December 1946, prepared by the Stevens Institute of Technology (Hydrodynamic Coefficients of a Self-Propelled Model of the SS475 Class Submarine).
2 Preliminary Report entitled "Performance Characteristics of Submerged Submarines, Tests on U.S.S. ENTEMEDOR (SS340)", dated 23 April 1946, prepared by The Woods Hole Oceanographic Institution.
3 ShipAlt SS206 of 5 December 1943.
4 BuShips ltr. SS/S48-23(515) of 13 August 1943.
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SECTION XVIII
SHOCK PROTECTION
18-1. The vulnerability of a submarine to damage from underwater non-contact explosions depends upon the shock resistance of its vital equipment and fittings at least as much as on the dynamic strength of its pressure hull. From the standpoint of vulnerability to underwater explosive attack, the ideal submarine can be considered as one with a hull having maximum damage-resistance for the weight of material devoted to it, and with all other equipment, appurtenances, systems, etc., of such strength or so well protected from shock that the pressure hull itself will be critically damaged before other vital components sustain serious damage.
18-2. The term "shock" implies a transient or sudden and violent change in the state of motion of the component parts or particles of a body or medium, resulting from the sudden application of a relatively large external force, such as a blow or impact.1 There are two distinguishing characteristics associated with shock motion: (1) the time duration of the motion is limited, and (2) generally the motion is non-periodic, that is, it does not repeat itself at regular intervals of time, as does, for example, a sustained steady-state motion such as a "forced vibration".
18-3. An object will acquire shock motion upon the application of a sufficiently intense force system whose characteristics vary with time. The nature of the motion will be determined by the nature of the applied force system and by the characteristics of the object, principally its mass distribution and elasticity. Shock motions may vary widely in character and type. The initiating force systems which produce shock motion on submarines when subjected to underwater explosive attack are the pressure wave or waves created in the water by the explosives (see Figure 15-1). It is fairly well established that, except for damage caused by the subsequent "whipping" of the hull, shock damage from underwater non-contact explosions is due almost entirely to the initial steep-fronted pressure wave created at the instant of detonation. Contrary to what might be expected, the most serious and extensive cases of shock damage to surface naval vessels have been the result of non-contact underwater explosions rather than contact explosions, probably because water is a more effective transmission agent than the structure of a vessel for distributing the shock throughout the vessel. In submarines, only the problem of non-contact explosions need be considered since contact explosions would invariably cause lethal damage by rupture of the pressure hull and, in any event, the magnitude of shock damage resulting from non-contact explosions is greater than for contact explosions.
18-4. Upon application of pressure pulse loading to a submarine through underwater explosive attack, a very complex transient motion may be induced in the hull structure. Structural members may acquire a very high velocity which endures
1 A detailed study of shock and shock protection methods is contained in NavShips Publication 250-660-26 entitled "Mechanical Shock on Naval Vessels".
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for a sufficiently long time to impart a substantial displacement to, and within, these parts. The motion of these structural members is eventually arrested by other parts of the ship's structure and by their own internal damping and elastic properties. This results in a reversal of the initial motion, followed by a transient roughly periodic damped vibration which characterizes the return of the members to their original position in cases of elastic deformation or to some new position in cases of permanently distorted structure. The sudden initial acquisition of velocity is by definition characterized by a high acceleration acting for a short time. Since objects directly mounted upon these structural members are restrained to move with their supports, they must also reach closely equivalent velocities and as a result be subjected to high accelerations. These high accelerations can produce extremely high inertia forces in certain parts of the equipment. The stress effects produced by these forces may be varied and numerous, e.g., breakage of materials having low impact resistance, rupture of pipe joints, misalignment of machinery, mal-functioning of relatively delicate mechanisms such as circuit breakers, relays, tripping and latch mechanisms, and derangement of relatively delicate equipment such as gauges, meters, radio and sound equipment. The classic equation which determines the magnitude of these forces is F = Ma, where "m" is the mass of the equipment being accelerated and "a" is the acceleration imparted thereto. Instead of considering "a" as a peak value only, it should be regarded as varying with time. The force "F" therefore also varies with time. Multiplying the peak acceleration by the mass of the object being accelerated will give the true peak force applied to the object at that instant but an erroneous impression of the response of the object to this force may result unless the time duration of the acceleration is taken into consideration. For example, certain materials, such as medium steels, can withstand the high forces resulting from application of a high acceleration for a virtually instantaneous period of time but may fail if the time duration is increased, whereas other materials, such as glass, may fail when subjected to the brief but high acceleration only. The force "F" may induce stress in a member of the ship's structure due to accelerating a piece of equipment mounted upon such structure; it may result in a stress component induced in the casing or chassis of a piece of equipment due to a difference in acceleration of the components mounted upon such casing or chassis; or it may induce stresses in an internal component of a piece of equipment due to the relative acceleration of a sub-component. Damage to equipment may be reduced or prevented by interposing a flexible mount between the equipment and the structural member of the ship so that motion can take place between the structural member and equipment mounted thereon. The equipment is thus gradually accelerated to the velocity of the ship's structure or to some lower velocity, if at all; i.e., the acceleration lasts for a longer time at a reduced magnitude.
18-5. Because of the importance of shock resistance to submarines, consideration has been given over a long period of years to this factor in the design of submarines and their components. Research in this
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field became more active in 1935 with the explosion testing of riveted and welded full scale caissons and has been continued since by this Bureau and by many naval field activities and private concerns. Included in the shock protection program for submarines were: (1) the further replacement of low impact materials with high impact materials; (2) use of resilient shock mounts, principally rubber, felt and molded phenolic material, for small items such as gages, lighting fixtures, electronics equipment, and resilient mounts plus common foundations for auxiliary machinery vital to submerged operation (in conjunction with sound-isolation); (3) use of fitted foundation bolts and/or large diameter dowels plus common foundations to retain alignment and reduce the effect of impact forces for various auxiliaries not used in submerged operations and hence where sound-isolation was not required, and for massive equipment such as reduction gears, main motors, etc., for which resilient mounting was not easily adaptable; (4) shock mounting on resilient rubber mounts of the entire propulsion control cubicle; (5) careful detail design of equipment, where possible, to absorb deflection if necessary without failure, i.e., increasing the energy absorption ability of the equipment; (6) careful detail design of mechanisms to produce characteristics which were inherently shock-proof or which could be made so by the use of simple anti-shock devices; (7) proper location of equipment so that the most favorable supporting structure could be utilized, and arrangement of equipment so that ample external clearance was available for movement of the equipment as a whole, and ample internal clearance so that component parts, such as vacuum tubes, could move relative to each other without causing damage, and (8) numerous other improvements such as laminated main battery cell jars, substitution of silver-brazed and welded piping joints for cone and bolted joints, and such small details as lock washers to prevent nuts from backing off and anti-shock retaining devices for ferrule type fuses, vacuum tubes, etc.
18-6. As the National Emergency was at hand and the research work being conducted with caissons and models was not being completed as rapidly as deemed necessary, it was decided that the task would be completed more rapidly by tests with a full scale submarine. Accordingly a series of such tests was conducted at Portsmouth, N.H. in 1941 with TAMBOR (SS198), TROUT (SS202), GAR (SS206) for the purpose of determining the vulnerability of all of the features of modern submarines to underwater explosive attack. Each of the three submarines was submerged to periscope depth and subjected to the detonations of 300-pound charges of TNT placed at depths of about 60 feet and at varying ranges and orientation with respect to the vessels. The closest charges in all three of the submarine experiments were 33 yards from the hulls. These tests revealed important deficiencies and the data obtained from them by expert observers formed the basis of practically the entire shock protection program for U.S. submarines. Information from these tests, obtained before our entry into the war, influenced the course of shock-proof design on U.S. submarines more than the combined total of the subsequent voluminous war experience since very few deficiencies
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were brought to light by actual war service that had not already been disclosed by the 1941 tests.
18-7. As a measure of the effectiveness of the various shock protection measures incorporated in our submarines, the controlled depth charge tests on DRAGONET (SS293) during April, May and June of 1944 off Portsmouth, N. H., provide interesting comparative data.1 Explosive charge weights, number of shots, ranges, and depths of DRAGONET and the charges were selected to be identical with the tests conducted on TAMBOR, TROUT and GAR in 1941 except that the ranges were corrected for the increased thickness of hull plating on DRAGONET so as to obtain approximately the same severity of shock loading. During all of the shots, DRAGONET was submerged to periscope depth. Fifteen charges were fired at a depth of approximately 60 feet, the first containing 600 pounds of TNT and each of the others 300 pounds of TNT, and at various ranges from 1500 to 75 feet as shown in Figure 18-1 below. The depth of water was approximately 150 feet. The observed damage to the vessel and equipment for the various shots is contained in Table 18-1 below.
FIGURE 18-1
1 David Taylor Model Basin conf. Report No. R-283 of April 1945 (Shock Measurements During Depth Charge Tests on USS DRAGONET (SS293).
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TABLE 18-1
Observed Damage to DRAGONET During 1944 Vulnerability Tests
Shot |
Location of Charge |
Damage |
1-5 |
Charges 1500 to 300 feet from the midship section on the port side. |
No damage resulted. |
6 |
Charge 200 feet from the midship section on the port side. |
During this shot various running lights and upper deck instruments broke. Within the ship, the water circulating pump of main motor No. 2 was thrown out of alignment. |
7 |
Charge 150 feet from the midship section on the port side. |
No damage resulted. This was undoubtedly due to the fact that the charge was unintentionally fired close to the surface of the water, rather than at the usual depth, 60 feet. |
8 |
Charge 138 feet from the midship section on the port side. |
The auxiliary gyro compass spilled mercury, causing the instrument to operate improperly. A pipe hanger in the pump-room was broken. |
9 |
Charge 100 feet from the midship section on the port side. |
The outer prism in periscope No. 2 was cracked and the instrument was jarred out of collimation. |
10 |
Charge 75 feet from the after quarter on the port side. |
Vents on a number of main ballast tanks were jarred open. |
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Shot |
Location of Charge |
Damage |
10 (cont'd |
Charge 75 feet from the after quarter on the port side. |
Both forward and after battery cells moved. Some wedges and strong-backs were loosened. Slight fissures appeared in the sealing compound of some cells. An SJ-1 radar rectifier tube, Type 5U4, in the pump room was broken. This tube was not shock-mounted. The voltmeter on lighting motor-generator set No. 2 was broken. The voltmeter on motor-generator set No. 2 was sticking. This meter was mounted on the control cubicle. The ammeter on main generator No. 1 in the engine room was sticking. The gyro repeater system was rendered inoperative. A non-shockproof lamp in a shock-mounted light fixture in the after engine room was broken. The rudder steering gear became defective. Sound heads, both port and starboard, became noisy when training. The radar training mechanism became noisy. Contact makers on a number of vents gave wrong indications. The port shaft transmitter was jarred out of alignment. Fuse retainers on the radar panel were jarred out of place. Mercury was splashed from the master gyro compass. In addition there were various air, hydraulic, and water leaks, and some equipment had shifted position. |
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Shot |
Location of Charge |
Damage |
11 |
Charge 75 feet from the midship section on the port side. |
A rough-service light bulb was broken. The telephone selector was not operating. The telephone ringer was broken. (The preceding three items were in the forward torpedo room.) |
12 |
Charge 75 feet from the forward quarter on the port side |
Only minor damage was reported. |
13 |
Charge 75 feet from the midship section on the starboard side. |
The master gyro follow-up in the control room became inoperative. A light bulb in the control room was shattered. Three cells in the forward battery tank showed fissures in the sealing compound. Threads were stripped from several strongback holding rods in the after battery tank. |
14-15 |
Charges 75 feet from the after and forward sections, respectively, on the starboard side.* * No examination was made between Shots 14 and 15. |
The hand training gear of the starboard sound head became stiff; the repeater was off 2.5 degrees. The port sound head became noisy when training; the repeater became erratic. The WDA motor-generator became very noisy, and vibrated excessively. The RBO speaker in the forward torpedo room was broken. A voltmeter in the forward battery room was broken. Several strongbacks in the after battery tank showed signs of springing. |
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Shot |
Location of Charge |
Damage |
14-15* (cont'd) |
Charges 75 feet from the after and forward sections, respectively, on the starboard side. |
The F.W. tank on the starboard side of the after battery room showed a pronounced displacement, and the hangar bolts were bent. A hanger holding a resistance box in the forward engine room was broken. An ammeter on No. 1 main engine board in the forward engine room became sticky. A voltmeter on No. 2 main engine room board in the forward engine room became sticky. The after torpedo firing mechanism was not working. |
18-8. DRAGONET represented a submarine on which practically all of the numerous items in the shock protection program had been accomplished. It is therefore significant to note that the shock damage resulting from the 1944 tests on DRAGONET was minor, even though the closest shot was fired at a range of 75 feet, whereas the 1941 trials of TAMBOR, TROUT, and GAR, on which only moderate shock protection had been accomplished, resulted in relatively serious shock damage although the closest shot was fired from 100 feet. The DRAGONET experiment demonstrates that considerable improvement has been made in the shock resistance of our submarines. However, it is known that the modern submarine can withstand depth charge attacks at ranges somewhat closer than the minimum range employed in the DRAGONET tests.
18-9. Several cases are available from war experience which afford a rough means of estimating the shock resistance of our submarines when subjected to near destruction from underwater explosions. The damage narratives of KINGFISH, TUNNY, SALMON, SCAMP and HALIBUT, included elsewhere in this report, represent five instances where considerable permanent pressure hull deformation was sustained by submarines on which all or a substantial portion of the shock protection program had been accomplished prior to their damage. A study of that portion of the damage suffered by these vessels which can be attributed to shock alone indicates that while properly shock-mounted vital equipment remained for the most part unaffected, although the submarines in each case were on the verge of being destroyed through failure of their pressure hulls, further improvements in shock protection is necessary particularly
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in piping and electrical systems. For example, damage to the control cubicles of TUNNY and SCAMP very nearly caused the loss of those vessels. It is interesting to note that in none of the cases cited above did sound-isolated equipment mounted on rubber compression type resilient mounts sustain any damage, nor has any report come to the knowledge of this Bureau, so far as can be determined, which indicates that equipment so mounted has ever received disabling shock damage on any U.S. submarine. This is significant since the problem of combining shock protection with sound-isolation is by its very nature a compromise, neither the shock protection nor sound-isolation reaching their optimum possible efficiency when provided concurrently by the same mount. War experience indicates that the degree of both shock protection and sound-isolation provided by properly mounting equipment on compression type rubber mounts is adequate. Various items of directly mounted machinery did sustain shock damage in all of the above actions, e.g., on HALIBUT the bedplates of the TBL motor generator, the ice machine compressor and the No. 2 air conditioning compressors were cracked. Damage to directly mounted auxiliary machinery has also occurred in cases where no pressure hull damage was sustained. In TAMBOR's (SS198) action of 3 February 1944, the bedplates of both high pressure air compressors in the pumproom were cracked around their complete periphery and both low pressure blowers were dislodged from their foundations. In GREENLING's (SS213) action of 25 January 1945, the bedplate of the No. 2 high pressure air compressor was cracked. In SARGO's (SS188) action of 14 June 1943, the crankcase of the No. 1 low pressure air compressor fractured, disabling the compressor.
18-10. General remarks regarding the shock resistance of various components of our submarines can be drawn from war experience as follows:
(a) Pressure hull structure. (Excellent) Areas of stress concentration under shock loading appear to have been held to a minimum through careful detail design (based on experience gained in controlled explosion tests of full scale models).
(b) Propulsion Diesel engines. (Excellent) With few exceptions, Diesel engines have remained operable even on vessels sustaining severe pressure hull deformation in way of machinery spaces.
(c) Main generators and propulsion motors. (Excellent) No reports have been received where direct shock damage has disabled propulsion motors or main generators.
(d) Propulsion electrical control equipment. (Good) Several cases occurred where propulsion was disrupted due to derangement of control equipment.
(e) Main reduction gears. (Poor) Very susceptible to tooth damage, causing high noise level.
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(f) Main battery. (Good) Laminated battery cells have occasionally cracked on vessels sustaining severe shock damage but the number where electrolyte was lost has in all cases been small.
(g) Resiliently mounted sound-isolated auxiliary machinery. (Excellent) No known cases of failure through shock damage.
(h) Directly-mounted auxiliary machinery. (Good) Several instances have occurred where directly mounted machinery has sustained fractured bedplates, misalignment, etc. However, directly mounted auxiliaries have in general been limited to those not essential for submerged operations.
(i) Piping. (Fair) Close attacks almost invariably cause piping leaks, frequently of serious nature.
(j) Auxiliary Power Systems. (Fair) Close attacks have frequently caused damage to or maloperation of relays, switches, controllers, etc.
(k) Torpedo tubes and firing gear. (Fair) Frequent shock damage has occurred to outer doors, gyro setting and depth setting spindles, stop bolts, guide studs, etc.
(l) Instruments, gauges, meters and light bulbs. (Poor) Close attacks generally caused extensive derangements to such equipment.
(m) Periscopes. (Poor) Periscopes were very susceptible to damage of disabling nature. Periscope derangements were reported in over 30 separate actions. In at least three instances, periscope damage forced termination of patrols.
18-11 The Bureau is cognizant of the need for further improvement in the shock protection of our submarines and is currently engaged in a research and development program toward this end. Particular emphasis is being given to correction of weaknesses disclosed by war experience for those components whose performance has been only fair or poor. It is apparent that shock protection is a continuing and expanding problem in view of the present tendency towards submarines of greatly increased hull strength for operation at extreme depths. However, shock protection is not the problem of the design and research agencies alone. It is incumbent upon building and repair activities and ship's force to install and maintain such protection in thorough and complete agreement with the best and latest data available. Shock protection and sound isolation standards should be as vigorously observed in time of peace as in war.
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SECTION XIX
ENGINEERING NOTES
19-1. When it is considered that the propulsion plant of a modern U.S. submarine, including the batteries, occupies about one-half the length and over one-third the volume of the hull, it is certainly remarkable that the incidence of serious damage to such equipment due to war action was extremely low. In only one known instance, GRENADIER'S (SS210) action of 22 April 1943, was a propulsion plant completely and permanently disabled, and in only one other known case, PERCH's (SS176) action of 2 March 1942, was a propulsion plant damaged so heavily as to be a significant factor in the eventual loss of the vessel.1 However, propulsion power submerged was temporarily disrupted on our submarines in over fifteen separate occasions as the result of underwater explosive attacks, and with serious consequences in a few instances. All of these temporary power disruptions were caused by failure of electrical equipment, principally through tripping of relays and contactors due to shock or jarring together of energized control cubicle busses. They occurred for the most part early in the war on older ships, where shock protection measures had not yet been carried out. That serious damage did not occur more frequently to U.S. submarine propulsion plants was due principally to the following: (1) the inherent ruggedness of the propulsion motors, generators, batteries, reduction gears, Diesels, shafting and propellers; (2) the improvements made in the shock design and shockmounting of vulnerable equipment, particularly the introduction of laminated main storage battery cells, shock-proof relays, shockmounted propulsion control cubicles and fitted foundation bolts to prevent misalignment of the propulsion motors and reduction gears; and (3) effective casualty control through split plant operation.
19-2. Although many casualties were sustained by U.S. submarine propulsion and auxiliary Diesel engines in the course of normal service, there are only a very few instances in which these engines are known to have sustained damage as the result of war action. War experience has conclusively demonstrated that modern U.S. submarine Diesel engines, both propulsion and auxiliary, regardless of make, are practically impervious to damage of disabling nature, even at those explosive ranges which will cause near destruction of the pressure hull. The experiences of KINGFISH (SS234), SALMON (SS182), SCAMP (SS277), and HALIBUT (SS232) are excellent examples since all four of these vessels sustained permanent pressure hull deformation in way of the machinery spaces.2 No damage at all was received by the Diesels on KINGFISH and HALIBUT. On SCAMP, No. 2 propulsion engine (FM Model 38-D-8-1/8) was disabled when the pressure hull bulged sufficiently to come hard up against the scavenging blower of that engine (Photo 9-11). SCAMP's other engines remained completely operable, however. On SALMON, all engines
1 GRENADIER narrative, Section VIII and PERCH narrative, Section IV.
2 KINGFISH, Section V; SALMON, Section VII; SCAMP, Section IX; HALIBUT, Appendix I.
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(GM Model 16-278A) either partially or completely flooded through leaking exhaust lines, but none were physically damaged by the attack. However, the drive shaft of the scavenging blower for No. 1 propulsion engine subsequently fractured when an attempt was made to start the engine before dewatering had been completed. SALMON's other three engines operated satisfactorily. On GRENADIER, in the action leading to her loss on 22 April 1943, the propulsion Diesels apparently remained operable after the bomb attack although severe hull damage was sustained in way of the machinery spaces, for it was reported that smoke was cleared from the interior of the boat, after surfacing, by running the engines. On PERCH, two engines remained operable after the first series of depth charge attacks but only one engine could be run after the second series of attacks. One engine limited her surface speed to about five knots. One of the three damaged engines (Winton Model 16-201A) was disabled by a broken camshaft. The cause of failure of the other two engines was not reported. The auxiliary Diesels were not damaged.
19-3. The most frequent casualties which occurred to Diesel engines incident to close underwater explosive attacks were the following: engines flooded through leaking exhaust valves;1 lube oil, fuel oil and circulating water lines ruptured or developed leaks, usually minor; engine foundation bolts sheared; and engine thermometers and other gages were broken or deranged. Such casualties are of minor nature, in no case have disabled an engine for more than a temporary period, and are not peculiar to war damage since similar casualties have occasionally resulted during normal service operations, due to leaking exhaust valves or excessive engine vibration. That our submarine Diesels have withstood close attacks with out minor or no damage occurring is attributable to the following reasons: (1) the rugged welded steel construction of the engine frames, resulting in high energy absorption characteristics, (2) the rugged construction of the engine components, and (3) the large mass of the engines. Assuming both to be directly mounted, the relative shock strength of a heavy item of equipment, such as a propulsion Diesel engine, need not be as great as the strength of a small and light item, as for example, a relay or an instrument. This is because a large, heavy item has a weight comparable in magnitude to the weight of the ship's hull and the foundation in the immediate vicinity of the equipment, and consequently the large mass and rigidity of the engine and its structural foundation modify the shock motion of the hull locally. Moreover, the rigidity of a Diesel engine is comparable to or may exceed that of the foundation and hull, so that for severe shock motions the hull and foundation will tend to absorb a relatively large percentage of the shock displacement, whereas the engine will remain almost stationary. In the case of a heavy machine, the forces that can be transmitted to the machine by shock may be limited by the strength of the foundation.
19-4. The propulsion motors and generators have also been singularly free from war damage casualties and for reasons similar to those
1 SALMON, Section VII; and PERMIT, 13 February 1944, Appendix I.
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enumerated above for the Diesel engines. There is no known case where propulsion motors or generators have been disabled on U.S. submarines through direct war damage to the motors or generators themselves, regardless of their type and make. In one case, SAILFISH's (SS192) action of 7 December 1943,1 a propulsion motor arced to ground and sustained brush rigging damage which disabled it until repairs were accomplished by ship's force, but this casualty was caused by failure of control equipment in the cubicle rather than direct damage to the motor itself. There are a few instances where brush rigging on propulsion motors has been slightly deranged or has jarred slightly out of position but the effects have been minor in all such cases. Reports have also been received where brush rigging on propulsion motors has been dislodged through shearing of rivets, or where brushes have overheated or chattered, and these casualties have been attributed to close depth charge or bomb attacks. However, it is believed that most of the latter cases were due to improper securing of the brush pigtails since such casualties also resulted from normal service operations. Corrective steps were taken in the manufacture of these brushes in 1944 and, so far as is known, no further brush difficulties were encountered thereafter. No reports have been received by the Bureau of any war damage having occurred to main generators. This is partly attributable to the fact that the generators are not energized during submerged operations and therefore derangements of control equipment will not cause minor damage to the generators, as has occurred in a few cases to propulsion motors.
19-5. The only component of submarine propulsion plants which war experience demonstrated to be particularly vulnerable to damage and which frequently caused loss of propulsion, was the propulsion electrical power and control gear, principally the equipment contained in the propulsion control cubicle. Of the fifteen cases known to the Bureau where propulsion failed temporarily on submarines while submerged and undergoing attack, all were due to electrical casualties. These casualties can be divided into three general types: (1) tripping of propulsion overload relays due to shock (later replaced by shockproof overload relays), (2) operation of relays due to momentary movement and short-circuiting of energized bus bars in the control cubicle and (3) control cubicle electrical fires caused by short-circuiting of energized circuits. The urgent need for improving the shock resistance of submarine propulsion electrical control equipment was demonstrated by the controlled depth charge tests conducted with TAMBOR (SS198) and TROUT (SS202) early in 1941, before our entry into the war. Two principal corrective measures were proposed: (1) improving the shock resistance of the separate components, such as switches, contactors and relays, and (2) the shockmounting of the entire propulsion control cubicle to reduce the acceleration forces on vital equipment contained in that enclosure. Following the tests on TAMBOR and TROUT, the submarine GAR (SS206) was provided with the first experimental installation of a shockmounted propulsion control cubicle, designed and constructed by the General Electric Company and employing
1 See Appendix I for brief of SAILFISH damage.
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rubber pads as the resilient material for shock reduction. Several experimental overload relays were also installed in GAR to test the relative merit of various designs. Controlled explosion tests were then conducted which demonstrated that shockmounting of the entire control cubicle was a practicable method of reducing damage to the vital electrical control gear and that the designs of switches, contactors, and relays could be so improved as to provide a high degree of inherent shock protection. The Bureau therefore authorized the shockmounting of propulsion control cubicles on both submarines in service and new construction.1 In addition, overload relays in the main battery power and propulsion motor and generator circuits were replaced with shockproof types and, on applicable submarines, lock-out cams were installed to prevent maloperation of the series and parallel contactors in the main control cubicle.2 As a result of TUNNY's (SS282) experience of 26 August 1943, where propulsion power was disrupted temporarily due to a fire which started when the positive and negative main battery busses in the control cubicle jarred together momentarily, the installation of small phenolic bumpers between the cubicle main battery busses was authorized for all applicable submarines to prevent recurrence of similar casualties.3
19-6. The effectiveness of the shock protection afforded by the above alterations can best be judged by the fact that so far as is known, with only four exceptions, all cases of loss of propulsion power traceable to derangement or maloperation of electrical equipment occurred prior to 1944 and on vessels which were not provided with shockproof relays and/or shockmounted control cubicles. The four exceptions were as follows:4 (1) TUNNY's action of 30 March 1944 in which energized bus bars short-circuited by movement against the control cubicle frame. This damage is believed traceable to the fact that, although the cubicle had been shockmounted, the shock protection afforded by the resilient mounts was reported to have been nullified by one support frame which was improperly mounted so that it made direct metallic contact with the cubicle cage. (2) PICUDA's (SS382) action of 20 May 1944 in which a close depth charge detonation tripped the starboard propulsion motor contactor in the control cubicle. The contactor was immediately closed, however, and propulsion was restored. (3) SANDLANCE's (SS381) action of 7 August 1944 in which the starboard propulsion control cubicle controllers were jammed by a broken washer and limited the maximum speed on the starboard shaft to two-thirds until repairs were made. (4) COBIA's (SS245) action of 14 May 1945 in which the battery and generator busses in the control cubicle arced, causing flame and smoke and the welding together of the contactors. Power was secured and the ship went to the bottom.
1 Authorized for new construction by BUSHIPS Itr. SS212-284/S41 (3660) of 11 December 1941 and for ships in service by ShipAlt SS131 of 7 August 1942 (delay for ships in service was due to priority assignment of materials and design work for ships being constructed).
2 ShipAlt SS218 of 17 November 1943.
3 ShipAlt SS222 of 6 November 1943.
4 Briefs of damage sustained by each of these four ships are contained in Appendix I.
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19-7. The importance of insuring that foreign objects and inadequately attached fittings are removed from areas over or adjacent to propulsion control cubicles has been illustrated by several experiences where propulsion power was lost and/or fires were started due to short-circuiting of energized power circuits by small objects falling from the overhead or being hurled into the cubicle from the sides. SCAMP's action of 7 April 1944 (Section IX) is such an example.
19-8. The presently accepted standard U.S. submarine main storage battery jars are of laminated construction having a hard rubber exterior and a soft rubber inner layer. War experience has demonstrated that battery jars of this type are highly resistant to shock and can be considered generally satisfactory for war service. The introduction of laminated battery jars together with improvements in the design and support of the battery tanks are major factors in the resistance of submarines to damage. The lining of the battery tanks with rubber also probably contributes to the shock-proofness of the batteries. Submarines which have sustained close attacks, but where no pressure hull deformation occurred in the vicinity of the battery tanks proper, have in all cases either had no battery jar damage at all or the jars have cracked on only a very small number of cells. It is also significant to note that in the majority of those cases where jars were reported as having cracked, no loss of electrolyte occurred since only the outer hard rubber exteriors of the jars cracked and the inner soft rubber portions remained intact. Even where jars have lost electrolyte and caused short-circuiting, no serious consequences have resulted since the damaged jars were easily disconnected. In only two instances have relatively large numbers of battery jars been damaged on U.S. submarines which survived close attacks; on HALIBUT (SS232), 14 November 1944; and on REDFISH (SS395), 19 December 1944. In both of these cases the battery jars were of laminated construction. On HALIBUT, the hull forward of frame 55 was extensively damaged and the pressure hull plating in way of the forward battery well was dished in by as much as from one to two inches. About seventy percent of the 126 jars in the forward battery developed cracks through their outer hard rubber casings (Photo 19-1). On all but eleven jars, the soft rubber inserts were undamaged and no leakage of electrolyte occurred. On the eleven jars which lost electrolyte, the leakage occurred through cracks in the jar bottoms. The fact that only eleven jars actually leaked, although a total of about eighty jars had cracks in their outer casings, is convincing evidence of the value of the laminated soft rubber insert construction. No damage was reported to have occurred to the after battery jars. On REDFISH, the forward portion of the pressure hull was also considerably deformed although no dishing was reported in way of the forward battery well itself. Twelve jars of the forward battery were cracked and lost electrolyte. No damage was sustained by the jars of the after battery. In neither of the above two cases did the damage to the batteries have serious effect on ship operation. When the extensive pressure hull damage which occurred close to the battery wells on both HALIBUT and REDFISH is compared with the battery damage on those two vessels, it appears that current submarine battery cells and their method of installation approach the shock resistance of the hull itself.
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19-9. In numerous instances, full battery grounds have developed as a result of close attacks. In most cases these have been traceable to short-circuits in the emergency lighting systems or short-circuiting of one or more cells caused by electrolyte spillage through cracks which developed in the battery cell top sealing compound and thence establishing leakage paths to uninsulated tie-rods and strongbacks connected to hull structure. Cracks occurred in the sealing compound due to shock but in many cases this tendency was aggravated by improper wedging or faulty tightening of strongbacks. To eliminate casualties due to acid spillage through cracked sealing compound, two steps were taken: (1) all tie-rods and strongbacks in the battery wells were insulated with a rubber compound, and (2) improved sealing compounds were developed. To facilitate locating the cause of battery grounds, switches were installed in the emergency lighting circuits on all fleet type submarines to permit separation of emergency lighting from the battery for battery ground readings.1
19-10. War experience has repeatedly demonstrated that reduction gear drive propulsion plants are unsuitable for modern submarine warfare in that the main reduction gears are extremely susceptible to tooth damage when subject to underwater explosions at even moderate ranges. Tooth damage causes high noise level, usually described as 'clicks", "thumps", or "knocks", which reduces or invalidates the military effectiveness of submarines since approach and evasion tactics then become hazardous or impossible when enemy vessels are equipped with sonar listening gear. In approximately eighteen instances, U.S. submarines have reported that excessive reduction gear noise developed as the result of enemy depth charge or bomb attack. In at least three actions, reduction gear damage forced early termination of patrols and the subsequent repairs to achieve quiet operation were long and expensive.2 Reduction gear damage has in no case prevented the gears from operating mechanically but has been objectionable from the standpoint of the introduction of high noise level. Tooth damage has apparently resulted either from sudden and violent movements of the pinion and bull gear masses relative to each other or in some cases perhaps from longitudinal movement of the entire propeller shafting. For example, a clicking noise developed in the reduction gears of APOGON (SS308) when forward area repair forces removed a damaged propeller on that ship, without drydocking, by detonating small explosive charges on the forward blade faces. Since the shaft coupling in the motor room was not broken, the shaft tended to move aft as a whole and caused sudden relative movement of meshing tooth surfaces in the reduction gear. A similar action could probably occur on a submarine when subjected to close underwater explosive attack In addition, the continuous reduction in self-generated noise accomplished by design improvement of components and by sound isolation measures resulted in the noise caused by reduction gears, even though undamaged, to become a prominent noise feature, whereas in earlier fleet submarines, the re-
1 ShipAlt SS224 of 21 December 1943.
2 SAND LANCE (SS381), 7 August 1944; BARBERO (SS317), 27 December 1944; and BERGALL (SS320), 13 June 1945. See Appendix I and Section XIV for details on damage.
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duction gear noise was not as high as that of other items. This, together with the war experience in regard to damage, led the Bureau to change from reduction gear drive for submarines to direct drive. The move, which required considerably more weight for the low speed direct drive motors, was made possible by weight savings that had been realized through careful design of various components and by the elimination of unnecessary ones.
19-11. Main engine air induction and ship's supply ventilation hull flapper valve discs and/or their seats have in several instances been deformed by close explosive attack. When the induction line itself concurrently flooded, as sometimes occurred, sea water then entered the machinery spaces, occasionally in considerable volume. Early in the war, leakage which developed around these hull flapper valves was in several instances successfully stopped or reduced to a minor quantity by forcing the valve flapper against its seat with the aid of a chain fall as on KINGFISH during her action of 23 March 1943 (paragraph 5-21, Photo 5-8). In July of 1943, gagging dogs were authorized for installation on engine air induction and ship's ventilation hull valves on those submarines not previously provided with emergency means of securing such valves.1 It should be noted that leakage through induction valves will always accumulate in after compartments and therefore may cause a submarine to become heavy aft, flooding of the topside induction piping also contributing to this tendency. The majority of instances where U.S. submarines have lost depth control due to flooding have been the result of added weight aft through induction hull valve leakage. The introduction of welded joints for the induction piping topside, commencing early in 1944, practically eliminated cases of flooding of such piping and therefore the prospect of flooding into the interior of the hull through distorted induction hull valves has been reduced markedly. Projected submarine designs will incorporate a snorkel type air intake and consideration will be given to running the induction piping system leading from the snorkel intake to the machinery spaces entirely within the confines of the pressure hull. The number of large openings in the hull for air purposes would thereby be reduced to only that at the snorkel itself.
19-12. Wiring passing through the pressure hull to external instruments or fittings exposed to full sea pressure has proved to be quite vulnerable to damage unless special precautions are taken. The failures encountered have been of two general types: (1) leakage through cable sheathing causing direct shorting of the cable conductors or allowing water to reach terminal boxes, switchboards, or equipment, and (2) leakage around pressure hull stuffing boxes. As an example of the former, the experience of SCULPIN (SS191), on her second patrol is interesting. On 7 February 1942, while undergoing depth charge attack at a depth of 345 feet, the multiple conductor to the port annunciator flooded through the annunciator box on the bridge. Water then passed
1 ShipAlt SS201 of 7 July 1943.
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through the length of the cable to the IC board in the control room, started a small fire, grounded numerous circuits, and ultimately placed the entire torpedo firing circuit and battle order transmitter and indicator systems out of commission. There are many cases on record where cables passing through the pressure hull have been forced inward through their stuffing tubes during close attacks, some by as much as one or two feet. In such cases, leakage has usually occurred at the stuffing tubes. Several corrective measures were taken to eliminate such casualties. Following a method developed by the Naval Shipyard, Portsmouth, rubber stop rings were vulcanized directly to cable sheathing at the outboard sides of all pressure hull stuffing tubes, using special molds for each size of cable, to prevent cables from being forced in.1 Cable ends external to the pressure hull were terminated with vulcanized seals to prevent water entering the sheathing. Similar methods were developed for packing terminal tubes and sealing cable ends for cables entering pressure proof fixtures. On older vessels, external cables no longer required for ship operation were removed and the hull stuffing tubes blanked. Cables leading from conning tower equipment to the main pressure hull, which formerly were routed outside the hull and therefore exposed to full sea pressure, were rerouted through a specially enlarged conning tower hatch trunk so as to be entirely within the pressure hull,2 and an additional cable trunk was authorized for installation between the conning tower and control room to accommodate the additional cable required for SJ radar and other new equipment. Casualties to external cables were practically eliminated in those vessels on which the above alterations were accomplished. In those few cases where cable sheathing leaks did occur subsequent to the above alterations, it is believed that the cause of leakage can be traced to improper cable end sealing.
19-13. On 17 August 1942, a serious fire occurred in the after battery tank of BASS (SS164) while operating off Balboa, C. Z., on her fourth war patrol. The fire was believed to have been caused by a short circuit resulting from leakage paths across phenolic insulation. Twenty-six members of the crew in after compartments, most of whom were asleep when the fire started, were trapped and died either through asphyxia or from the toxic effects of the fumes generated by burning phenolic material. In order to eliminate the possibility of similar casualties on other submarines, instructions were issued to remove phenolic material from certain places in submarine battery tanks.3 On 7 April 1944, another serious casualty resulted from burning phenolic material, this time on SCAMP (SS277), and very nearly caused the loss of the vessel.4 On that ship, large quantities of toxic phenolic smoke were generated by a very small electrical fire at a phenolic-insulated rotary switch in the control cubicle. The Bureau was long aware of the undesirable properties of phenolic resins for shipboard insulation use and during the war years many research and development contracts were let with industry with
1 Authorized by BuShips ltr. SS/S62-2(660u-815); EN28/A2-11 of 31 March 1944.
2 Authorized by BuShips conf. ltr. SS/S62-2(515) of 2 March 1944.
3 BuShips ltr. SS/S39-1(8660-3660); EN28/A2-11 of 10 October 1942.
4 See SCAMP narrative, Section IX.
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the view of obtaining a more satisfactory material. By early 1944 a new organic insulation material made of melamine resin rather than phenolic resin had been accepted. Tests demonstrated that the insulation and shock properties of melamine were equal to or greater than those of phenolic but that melamine would not support combustion. Phenolic material, once ignited, will continue to burn and will generate large quantities of toxic fumes, whereas the combustion of melamine will result in only 40 percent toxic gases as compared with phenolic material, will only decompose when actually subjected to high temperature, as from an electric arc caused by short-circuiting, and all combustion will immediately stop when the source of heat is removed. It is possible on SCAMP, for example, that the volume of toxic gases given off by the burning phenolic material was very much greater than the volume of gases which would have been generated had melamine material been installed. By May of 1944, melamine production had reached a sufficient volume so that its use as an insulation material combined in laminated construction with glass cloth was authorized for submarines, the first installations being made in the split-type control cubicles on direct drive submarines then under construction. The introduction of melamine insulation for submarine electrical equipment is considered to have greatly reduced the hazard from toxic gases originating from electrical fires and constitutes an important peacetime safeguard as well as a wartime necessity.
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Photo 19-1: HALIBUT (SS232). View showing cracks in hard rubber outer casing of laminated battery jars on HALIBUT (SS232) as a result of her action of 14 November 1944. Although about 80 jars of the forward battery developed cracks in their outer casings, only 11 jars lost electrolyte.
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SECTION XX
PIPING
20-1. Leakage from air systems in submarines as a result of war damage can be a matter of great concern, particularly in the case of air leakage which occurs in main ballast tanks or at other points external to the pressure hull. The high pressure air system naturally constitutes the greatest potential air leakage hazard on submarines since that system is normally maintained at a pressure of about 3000 pounds per square inch, the piping extends throughout the entire length of submarines, and the major portion of the air reservoir is contained in air banks located in ballast tanks external to the pressure hull.
20-2. Depth charge vulnerability tests conducted with TAMBOR (SS198), TROUT (SS202), and GAR (SS206) early in 1941 demonstrated conclusively that cone joint connections in high pressure air systems did not satisfactorily withstand attack at close range. In so far as shock is concerned, cone joints are fundamentally undesirable since such joints are relatively loose and will pound when subjected to sudden and violent movements. This will cause large stresses to be built up, and, as the tightness of a cone joint is dependent upon metal to metal contact of the "belled" portion, any accompanying distortion of the sealing surfaces will result in leakage. The Bureau therefore authorized an extensive program to convert the high pressure air system joints on all fleet type submarines to silver-brazed connections and special union-type fittings having plastic annular ring seals.1 Although this program commenced in November 1941, the magnitude of the work involved required that the changes be accomplished on submarines during their regular overhaul periods, and consequently many of the submarines then in service were not modified until late in 1942 or early in 1943. In addition, the high pressure air systems on submarines in service and those in late stages of construction were in most cases only modified to cover the joints in the ballast tanks, battery compartments and easily accessible internal fittings, so that cone joints still remained in numerous locations on many ships even up to the end of the war. As a corollary alteration to the joint modifications, it was directed that all high pressure air flasks in fuel tanks be removed and reinstalled in main ballast tanks to eliminate the possibility of air leaks in fuel tanks causing oil slicks or tank rupture.
20-3. Throughout the war, there were at least twenty-five instances in which high pressure air systems on U.S. submarines developed leakage following depth charge or bomb attacks. In most of these cases, the air leakage was relatively small and had no serious consequence. The KINGFISH, TUNNY, TANG, and HALIBUT actions are among the few instances where there was important internal air leakage.2 On
1 Authorized by ShipAlt SS62 of November 1941. The modification of fittings in tanks external to the pressure hull was classed as a Class "A" Alteration. Modification of fittings within the pressure hull was classed as a Class "B" Alteration.
2 See KINGFISH narrative, Section V; TUNNY narrative, Section VI; TANG narrative, Section X; and brief of HALIBUT damage, 14 November 1944, Appendix I.
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KINGFISH (SS234) and TUNNY (SS282), the leakage occurred at cone joints of the high pressure air receiving and distributing manifolds. The resulting increase in internal air pressure on KING FISH, was reported to be one of the factors which eventually forced her to surface. In the case of the air leakage which occurred on HALIBUT (SS232) one of the "tee" fittings at No. 1 high pressure air bank in the forward battery compartment carried away and the entire bank bled down rapidly.
20-4. Although many instances were reported where high pressure air lines within ballast tanks developed leakage, in none of these cases was a submarine forced to surface due to increase in buoyancy through rapid accumulation of air pockets in the tanks. In at least one case, THRESHER's action of 9 July 1944, air bubbling to the surface from main ballast tank high pressure air leaks (vent valves were open) is believed to have enabled detection by the enemy.
20-5. Instances where high pressure air leakage developed as the result of enemy attacks continued to occur up to the end of the war. However, these casualties were limited for the most part to older submarines in which the cone joints of existing high pressure air systems had either been modified for silver-brazing or were still installed. There were remarkably few cases of high pressure air leakage on those later vessels which were built with air systems having all connections either silver-brazed or fitted with special union joints. Silver-brazed connections are believed to be completely resistant to depth charge attack when properly installed. The most important factor in proper installation is to insure that the clearance between the fitting and the piping is correct so that the brazing material will flow by capillary action. A good installation is facilitated by the use of fittings of the approved pre-inserted ring type, and tests have demonstrated that failure should occur in the pipe or fitting rather than the joint. It is believed that all cases where silver-brazed high pressure air system joints failed on submarines were due to one or more of the following reasons: imperfect brazing technique; excessive clearances in joint assemblies; the use of existing fittings which perhaps were excessively weakened when modified for silver-brazing, or the use of fittings which were reheated too many times either during the initial installation or through repeated use. The resistance of silver-brazed joints to explosive attack is dependent in very large measure upon the skill of the silver-brazing operator, the quality of the supervision and the methods of inspection. The special union-type joints using plastic annular ring seals have proved remarkably resistant to damage, there being no reported case in which serious leakage can be identified as having occurred at such joints through war action.
20-6. The forward and after main ballast tank vent risers, as installed on submarines prior to SS417, pass through the forward and after torpedo rooms and are subject to full sea pressure at all times. In addition, when a submarine is under attack these risers are exposed to explosive loading from close detonations. During the war a number of cases of leakage at the flange joints were experienced. In one case, the copper riser had been dented in installation to clear an interference and under depth charge attack the dent was straightened out, fouling a passing shaft. As a result of these factors there was considerable concern in the submarine service over the hazard involved in having these risers, open to the sea, passing through the torpedo rooms. There were in
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service two types of risers, steel and copper. The copper risers had been installed to avoid corrosion and loss of strength in service. Both types were stronger than the pressure hull. However, the copper risers and their bronze flanges were subject to plastic deformation and were thus more vulnerable to flange leakage than the steel risers. The flanges of the steel risers involved no greater hazard, if properly installed, than any other flanged hull connections. It was usually possible to stop any leakage by tightening the flange bolts. However, in one case, TUNNY's action of 1 September 1944, damage by bomb attack caused leakage at the flanges of the internal port vent riser of main ballast tank No. 7 in the after torpedo room and this leakage was the determining factor in the Commanding Officer's decision to terminate the patrol (Photo 20-1).1
20-7. Measures were instituted during 1943 in an effort to improve the resistance of internal ballast tank vent risers to flange leakage. The copper risers and bronze flanges then in service were replaced with new risers of seamless drawn or specially welded steel tubing fitted with steel flanges.2 All new construction submarines were already being provided with steel risers. Steel is a more satisfactory material for such service since its strain energy within the elastic range is much greater than that of copper. Instructions were issued to make special efforts to secure tight joints during the assembly of internal riser piping by truing the flanges to avoid bolting strain, by using pressed asbestos gasket material rather than rubber or cloth inserted rubber gaskets, and by installing lock washers under the flange nuts to prevent backing off. In addition, branch lines were eliminated in order to reduce the number of joints. It is believed that the major cause of trouble with these risers was improper installation in which the flanges were not properly regulated and in which the bolts were overstressed or thick rubber gaskets were used to correct improper flange fit. However, it was recognized that the psychological effect of such risers should be eliminated and a rearrangement of tankage in new construction submarines was undertaken in order to relocate the torpedo room main ballast tanks so that no vent risers would be required. Commencing with the SS417 Class, the forward ballast tank was located ahead of the forward torpedo room in the position previously occupied by the forward trim tank, and the after ballast tank was eliminated completely, displacing it with a variable fuel oil tank. Although the internal risers on submarines previous to SS417 will continue to be a source of concern under attack, and are therefore undesirable, it is considered that the hazard is one of flange leakage, usually in controllable amounts, rather than of sudden rupture leading to the loss of the vessel. The strength of the steel vent risers is considerably greater than that of the hull and consequently the risers are less liable to rupture than the adjacent pressure hull. War experience demonstrated that the strength of the risers was sufficient to prevent failure even in cases where adjacent pressure hull structure was considerably deformed.
1 See brief of TUNNY damage of 1 September 1944 in Appendix I.
2 Ship Alt SS171 of 16 March 1943.
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20-8. The hydraulic systems of U.S. submarines extend throughout the entire length of the vessels but, unlike the high pressure air system, are wholly confined to the spaces within the pressure hull. Hydraulic power has been extensively developed by the U.S. Navy for submarine applications and on vessels now in service the following vital equipment is hydraulically operated: rudder, diving planes, periscopes, radar masts, negative and safety tank floods, main engine air induction outboard valves, ballast tank vents, engine exhaust valves, sonar hoists and torpedo tube outer doors. Hydraulic system piping must therefore be extremely resistant to depth charge attack. War experience demonstrated that such piping frequently developed minor leakage at joints and connections as a result of close attacks, but that, with few exceptions, the numerous cases where failures in hydraulic power occurred could generally be traced to causes other than loss of hydraulic oil through leakage. By far the most frequent cause of hydraulic power failure was the loss of auxiliary electrical power supplying the main hydraulic IMO pump motors and the motors driving the Waterbury hydraulic pumps for the diving planes and steering gear. These failures occurred when the submarines concerned were not rigged for silent running and in such cases hydraulic control of equipment was usually quickly regained by shifting to hand hydraulic power. Although there were numerous cases where minor leakage developed at cone joint fittings and a few instances where leakage occurred at silver-brazed or special joints as the result of close attacks, such leakage was generally of small amount and, at cone, flanged or union joints, usually could be easily stopped.
20-9. There are several instances where hydraulic piping derangements caused loss of power to vital equipment. For example, SALMON (SS182), in her action of 30 October 1944, temporarily lost steering control when the hydraulic supply line from the Waterbury pump tore loose at the steering hydraulic manifold.1 However, steering was soon restored by shifting to hand power and later to emergency power. THRESHER (SS200) was forced to terminate her tenth patrol when, as a result of depth charging on 13 November 1943, sea water entered the hydraulic system through a leak in the external replenishing tank or piping forward of the conning tower. These external hydraulic oil replenishing tanks constituted an obvious weakness and were subsequently removed on all submarines to prevent recurrence of sea water contamination, as on THRESHER, and to place hydraulic systems entirely within the protection of the pressure hull. On REDFISH (SS395), as a result of a depth charge attack on 19 December 1944 during her second war patrol, the entire main hydraulic system was temporarily put out of commission by loss of hydraulic oil due to leakage at piping connections at the pump-room accumulator, steering manifold aft, and sonar and bow plane tilting piping forward.2
1 See Paragraph 7-31.
2 See brief of REDFISH damage in Appendix I.
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Photo 20-1: TUNNY (SS282). View showing damage which occurred to port vent riser of MBT No. 7 in after torpedo room of TUNNY (SS282) as a result of her action of 1 September 1944. Patrol was terminated due to excessive leakage which occurred around bolts of the two flanges shown, rendering submerged operations dangerous. Pulling of flanges is indicated by the absence of the cork insulation in their immediate vicinity.
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20-10. As a result of the TAMBOR, TROUT and GAR tests in 1941, which disclosed that the cone joints in hydraulic systems would start minor leaks when subjected to shock and that such leaks could be a considerable nuisance when located in relatively inaccessible areas, the Bureau directed that hydraulic piping on new construction submarines thenceforth be provided with silver-brazed sleeve type joints in lieu of cone joints, with the exception that special joints approved by the Bureau, such as union plastic seal ring joints or Van Stone joints, were to be used where piping must be dismantled to permit overhaul of machinery. The resistance of submarine hydraulic systems to shock damage was markedly increased by the introduction of silver-brazed and union plastic seal ring joints in lieu of the cone joints. However, the fact that close attacks continued to cause hydraulic system leakage up to the end of the war certainly indicates that further improvements are required before these vital systems can be considered to be as invulnerable to damage as their importance warrants. The experience of REDFISH (SS395), mentioned in paragraph 20-9 above, is illustrative of this need. Van Stone type joints, of which many remain in current hydraulic installations, appear to be fundamentally less desirable for severe shock service than silver-brazed and union plastic seal ring joints. Unfortunately, those reports received from submarines noting hydraulic system leaks have rarely identified the types of joints or connections at which the leakage occurred. Leakage has occurred at silver-brazed joints, however, and the remarks in paragraph 20-5 above apply with equal force to the quality of silver-brazed joints in hydraulic systems.
20-11. Impulse air systems for the forward torpedo tubes have on several occasions developed leakage at points outside the pressure hull as the result of close attacks. The air reservoir for the forward impulse air system on U.S. fleet type submarines consists of shatterproof flasks located in the forward superstructure. Since this location is external, the air flasks and piping to the pressure hull are subject to full explosive loading, and any leakage which may develop external to the pressure hull will result in air bubbles rising to the surface. Unfortunately, sufficient space is not available in the forward torpedo room to permit interior stowage of these bulky impulse air flasks. In at least one instance, external leakage from the forward impulse system had serious consequences. On 14 January 1943, during her sixth war patrol, PIKE (SS173) was heavily depth charged by several Japanese destroyers.1 Six hours after the initial attack, PIKE planed up to periscope depth but was promptly bombed by an enemy plane. Periscope observations at this time disclosed that large air bubbles were rising to the surface from the impulse air system forward and this evidence of PIKE's location undoubtedly enabled the enemy to make the prompt attack. The external portions of the forward impulse systems are considered to be inherently vulnerable to damage for the following reasons:
1 See brief of PIKE damage in Appendix I.
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(a) the flasks are in an exposed location;
(b) the joints in the piping leading from the flasks to the torpedo room are of bolted flange type construction;
(c) the bolted through-connection for each pipe at the hull is particularly vulnerable to damage should the adjoining pressure hull sustain deformation;
(d) on war patrol, the flasks are normally maintained with air at pressures in excess of 300 pounds. It is hoped that investigations now underway on methods of ejecting torpedoes without the use of air may perhaps eventually permit the removal of torpedo impulse air systems.
20-12. Main engine air induction and ship's supply ventilation outboard piping sections as installed on U.S. submarines through 1943 were connected with bolted flanged joints. These joints were the source of leakage into the induction and ventilation systems in numerous instances where close attacks were sustained. In approximately 20 cases, the leakage was serious enough to warrant mention in war patrol reports as a major defect. Sudden flooding of induction systems in several instances caused immediate loss of depth control on the submarines concerned. In addition, when the induction or ventilation hull valves were damaged at the same time the outboard piping flooded, leakage occurred into the engine and maneuvering spaces, in some cases with serious consequences.1 As a result of numerous casualty reports, authority was granted in January 1944 to eliminate all bolted flanged joints and substitute welded joints in the main induction and ship's supply ventilation piping.2 There are only a few instances on record where submarines have sustained main induction or outboard ventilation leakage after this alteration was performed, SEAHORSE's (SS304) action of 18 April 1945 being one notable case. It is significant to note that although three submarines received very heavy damage on patrols subsequent to being provided with welded joints, on none of these three boats was leakage into the main induction piping reported.3
20-13. In two instances, main induction piping partially or completely collapsed under close attack: SALMON (SS182), Section VII; and SCAMP (SS277), Section IX. In addition, on SCAMP the main induction pipe wall was torn in four places by its welded bracket supports.4 The fact that collapse of main induction piping occurred on the above mentioned ships demonstrates that the strength under explosive loading of the induction
1 See WHALE (SS239), 30 October 1942, Appendix I; PERMIT (SS178), 13 February 1944, Appendix I; GRENADIER (SS210), Section VIII; and KINGFISH (SS234), Section V.
2 BuShips conf. ltr. C-SS/S48-23(515); EN28/A2-11 of 10 January 1944.
3 ICEFISH (SS367), 26 October 1944; HALIBUT (SS232), 14 November 1944; REDFISH (SS395), 19 December 1944. See Appendix I for briefs of damage.
4 See SCAMP, Paragraph 9-22 and Photos 9-5 and 9-6.
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and ventilation outboard piping on those two Classes was less than that of the pressure hulls. There are no known cases where induction piping has collapsed on SS285 Class and subsequent submarines. It should be added, however, that these large tubes running for long distances outside the pressure hull with large exposed areas and rather light connections to the pressure hull constitute a hazard, the elimination of which would make an important improvement in the resistance of a submarine to damage. Future designs will probably incorporate an internal induction line leading directly from a snorkel intake to the engine spaces.
20-14. Close underwater detonations have frequently caused numerous valves in submarines to leak due to rotation of the disc and spindle or distortion of the valve discs or stems. For example, COD (SS224), during her sixth war patrol, reported "During the depth charge attack on 24 April 1945 the first string of charges was of such intensity as to cause the discharge sea and stop valves in the officers' head to open violently; the sea valve operating handwheel was observed to spin rapidly and the stop valve operating lever was thrown to the open position with such force as to shear the pin joining the hand lever to the vertical operating shaft. The stop valve was closed with difficulty, using a wrench." COBIA (SS245) similarly reported that, on 14 May 1945 during her fifth patrol, the water closet valves spun to full open on each of several close detonations. War patrol reports occasionally contain mention of valves which were reported to have opened by as much as three to five full turns as the result of depth charge or bomb attack. In most instances, the opening of valves or leakage due to valve deformation has constituted a nuisance value only. The usual consequences were that full sea pressure was transmitted to internal piping systems, sanitary tanks flooded, inboard vents sprayed water or oil, etc. One of the most frequent damage control measures which submarine personnel were forced to take during attack was the simple task of closing valves which opened. The numerous war patrol reports which mention that valves backed off indicate globe valves were particularly susceptible to rotation and that generally valves throughout the length of the boats were affected rather than those confined to localized areas. The action was not limited to valves exposed to sea pressure for there were many reports where hydraulic and air system valves were affected.
20-15. In a few instances, the chain of events caused by the opening of a valve had serious effects. The following experiences are illustrative:
(a) On 26 October 1944 during her first patrol, ICEFISH (SS367) lost the use of her entire hydraulic system when the 225-pound air supply valve to the hydraulic system vent and replenishing tank jarred open and caused the loss of much of the oil in the system1 This in turn disabled the diving planes and steering until the hydraulic system could be refilled with oil. In addition, a fuel tank inboard vent valve on ICEFISH jarred open in the after battery compartment, causing profuse leakage of oil into that space, and the forward sanitary tank flooded from sea when the discharge line valves opened.
1 See brief of ICEFISH damage in Appendix I
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(b) On 4 November 1944, during her twelfth war patrol, the No. 7 torpedo tube inboard vent valve on SAILFISH (SS192) jarred open as the result of a bomb attack. The large volume of water which entered the after torpedo room through this vent caused the boat to assume a 25 degree up angle and depth control was lost.
(c) On 26 June 1945, during her sixth war patrol, No. 2 sanitary tank on PARCHE (SS384) flooded through the outboard vent which jarred open under attack, and a considerable amount of seawater entered the crews' mess and washroom through the inboard vent of the same tank.
20-16. A program of development and design of explosion resistant valves and locking devices to prevent rotation is currently underway at the Portsmouth Naval Shipyard. One of the features of this program is the actual explosive testing of various valve designs under simulated conditions. It is interesting to note that no large amount of valve rotation has yet been observed as a result of the tests, a 30 degree or one-twelfth full turn rotation being the maximum so far obtained. However, it has been found that deformation of valve stems and discs occurs such that a one-fourth turn of valve handwheels is sometimes necessary to secure tightness after a test. It is of course extremely desirable that valves remain tight during depth charging but the most important requirement is that submarine valves be so designed that although leakage may occur due to deformation or rotation under attack, they will be capable of being made tight again by simply taking up hard on the handwheel.
20-17. In the case of a globe valve, the factors that keep the valve closed under normal conditions are the friction of the thread surfaces in combination with the lead angle of the screw thread, and rotational inertia, the latter being a negligible influence. Under explosive attack, the valve and its supporting structure are set in vibration and it is believed that the friction loads will from time to time be zero or appreciably reduced during the vibrating process. At such a time, it is believed that asymmetrical rotational accelerations can easily make the valve rotate. For example, one way to unscrew an obdurate bolt is to vibrate it while simultaneously applying a torque. In practice, a depth charge attack consists of a series of impulses and the vibrations in submarines are prolonged. One factor which would certainly increase the prospect of rotation of a globe type sea valve would be where the valve disc is deformed by direct pressure pulse loading so that it no longer seats, thus reducing the friction on the threads and rendering it relatively easy for later rotational forces to spin the valve. It is considered that the Portsmouth tests may have failed to produce appreciable valve rotation because the test structure used was more rigid than that of a submarine hull, the test valves may have been initially tightened to a greater degree than would normally be the case with many valves aboard a submarine in actual service, and consecutive explosions were not employed.
20-18. In an effort to reduce the possibility of war damage, various alterations were authorized in order to reduce the number of piping connections passing through the hull and to provide various piping connections subject to sea pressure with both sea and stop valves where such had not been originally installed and war experience indicated to be desirable. Among the many items eventually eliminated on sub-
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marines in service and omitted from the designs for new construction were the following: secondary drainage lines external to the pressure hull; external piping systems penetrating more than one tank; outboard battery exhaust lines; external voice tubes; external conning tower ventilation lines; magnetic compass binnacle tubes; salvage air connections to normal and reserve fuel oil tanks; conning tower flooding line and escape gage sea connections; trim line deck hose connections; various water closet overboard connections; differential gage lines on main ballast tanks; and auxiliary engine exhaust piping. Hull stop valves were provided for the following lines where only sea valves had been previously installed: fuel ballast tank differential gage lines; fuel ballast tank filling and transfer lines; and fuel oil filling connections. The cumulative benefit of these and similar alterations, most of them minor, certainly reduced the vulnerability of our submarines to damage and decreased the number of items to which damage of "nuisance" value was commonly experienced.
20-19. In summing up the lessons learned from war experience with regard to submarine piping systems, the following general observations can be made:
(a) silver-brazed, welded or special union joints and connections should be used wherever possible on all piping where subjected to severe shock loading, both within and without the pressure hull, and even at the expense of increasing the time and cost of repairs;
(b) further development work is required to obtain flanged type joints which will be as shock resistant as silver-brazed, welded or special union joints under war service conditions;
(c) proper sectionalization of vital piping systems to isolate damage, and training of the crew in the use thereof, are of great importance;
(d) the number of hull openings should be held to an absolute minimum;
(e) explosion resistant sea valves and anti-rotational locking devices must be developed;
(f) piping should not penetrate external tank divisional bulkheads;
(g) sea chests or piping leading to sea chests should not be located in fuel tanks;
(h) brackets should not be welded directly to exposed steel piping, as in the case of the induction piping on SCAMP;
(i) the utmost care must be taken in the design, installation and maintenance of piping systems and detail fittings to prevent weak points;
(j) war experience has demonstrated that piping systems on submarines have been more subject to damage, although usually of a nuisance type, than the hull structure, main propulsion plant and principal auxiliary machinery.
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SECTION XXI
HABITABILITY
21-1. Habitability aboard a submarine is a measure of the adequacy of provisions for light, air, humidity, temperature, water, food, rest and recuperation facilities for the crew. In patrol reports submitted by our submarines during World War II, those conditions most frequently commented upon as adversely influencing habitability were: the deficiencies of ventilation and air conditioning while surfaced, submerged or running silent; poor breathing conditions incident to prolonged periods submerged due to accumulation of CO2, depletion of oxygen and increase of air pressure within the boat; the discomfort of cold, wet and rough weather while running surfaced; overcrowding; the inadequacies of water supply and sanitary facilities; the presence of certain noxious or toxic agents such as chlorine gas, carbon tetrachloride, oil fumes, and combustion products incident to fires; and material damage incident to enemy action or accidental flooding.
21-2. In a survey conducted by a representative of the Bureau of Medicine and Surgery of the reports of 1406 war patrols made by fleet type U.S. submarines during World War II, it was found that 658 war patrol reports contained no mention of habitability and conditions on those patrols are therefore presumed to have been fair or better, 106 reported "excellent" habitability, 408 reported "good" habitability, 171 reported "fair" habitability and 63 (4%) reported "poor" habitability. Of the 63 patrols reporting poor habitability, marked inefficiency resulted in only 23 of these due to unfavorable conditions and in only seven patrols was poor habitability in one form or another a deciding factor limiting patrol endurance. Five of these seven patrols were terminated due to contamination or shortage of fresh water and two were terminated due to prolonged conditions of high heat and humidity resulting from lack of air conditioning. Habitability conditions improved notably during the war as new submarines came into service and older submarines were modernized during overhaul periods. After 1942, the percentage of "excellent" reports received was doubled and the percentage of "fair" reports was considerably lowered. During 1943 and 1944 the percentage of reports of "poor" habitability was better than halved and remained at an all time low in 1945. However, the number of reports of only "fair" habitability at no period dropped to an insignificant level, indicating that much room for further improvement exists.
21-3. The program of installation of air conditioning equipment on U.S. submarines, which commenced in the PLUNGER Class in 1936, constituted a major improvement in the military utilization of our submarines for it made possible extended patrols in tropical waters. The principal benefits of air conditioning for submarine use are twofold:
(a) the insulation life of electrical equipment can be greatly lengthened by a reduction in humidity, and casualties due to water condensation or dripping on exposed and energized electrical circuits can be avoided;
(b) comfortable and healthful atmospheric conditions for ship's company can be maintained.
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21-4. There is no more important measure of the habitability of a submarine operating under war conditions than the adequacy of its ventilation and air conditioning systems. Since the earliest installations, the cooling and dehumidifying capacity of air conditioning equipment as installed aboard submarines has been continuously improved, keeping ahead of tremendous increases in crew carried and heat dissipating equipment installed. Frequent casualties during the war were experienced which temporarily disabled the air conditioning systems or, in a few instances, put the equipment out of commission for the major portions of patrols. It is to be noted, however, that U.S. submarines were not only the first to be air conditioned but at the end of the war, virtually the only ones with any significant air conditioning.
21-5. Unfortunately, under war conditions air conditioning and ventilation equipment could not be operated at all times. When conducting an attack approach or employing evasive tactics to escape enemy antisubmarine measures, U. S. submarine operational doctrine calls for the establishment of "silent running". In such circumstances, Commanding Officers usually followed the practice of securing inboard ventilation and air conditioning machinery to achieve minimum noise level, even though this equipment was sound-isolated on many submarines. Lack of air conditioning and ventilation while operating submerged in tropical or semi-tropical waters has almost invariably resulted in high humidity and excessive heat conditions within a very short period of time. Numerous patrol reports have stressed the deleterious effects on personnel of extended periods of silent running and in a few cases the military efficiency of our submarine crews was reported to have been seriously reduced during critical periods. For example, PLUNGER (SS179), while submerged and in contact with the enemy on 1 March 1943 near Makin Island, reported "Noisy air conditioning equipment was shut down as we went in across the bow of the escort. Temperature in the maneuvering room was 130°F. and the engine rooms were about the same . . . men in these two compartments were near prostration from the heat; one man was already receiving treatment. The men on the wheels and planes were being rotated every 5-10 minutes by which time they were totally exhausted . . . Response was slow and acuity dull. Errors were prevalent. It was evident that the ship no longer was in condition to fight or defend itself". PLUNGER thereupon broke off the action without attacking.
21-6. As an example of difficulties encountered when without the benefit of air conditioning during even normal submerged operations, the following excerpts are quoted from TAMBOR's (SS198) second and third patrol reports. "Due to faulty air conditioning units (leaks in Freon piping) the boat was oppressively hot and humid and there was a strong tendency for electrical grounds and short circuits to develop and for finely adjusted contraptions and mechanisms to become inoperative through corrosion. After two weeks of all day submergence all the bunks were wet and stinking. Clothing in the lockers in the forward and after torpedo rooms was green with mildew; practically everyone had a heat rash. There were two cases of heat exhaustion. . . . 30% of the crew developed some type of fungus infection . . . men and some of the officers resorted to sleeping in the torpedo room bilges where it was not quite so hot . . . Lack of air conditioning decidedly had a debilitating effect on the crew and slowed their reactions".
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21-7. During prolonged periods of submergence, further deterioration of the atmosphere has generally been experienced due to excessive accumulation of CO2 and depletion of oxygen. The physiological effects of prolonged exposure to such conditions are well known to submarine personnel. To revitalize depleted air, oxygen replenishment with or without the use of compressed air was commonly employed in conjunction with removal of CO2 by use of chemical absorbents. Foul air together with high humidity and extreme heat due to lack of air conditioning have in several cases seriously reduced the efficiency of our submarine crews. For example, enemy action forced PUFFER (SS268) to remain submerged for 38 hours during her first patrol, the longest known dive made by a U.S. submarine during the war. It was reported that "at the end of 38 hours submerged the men were breathing heavily and almost completely exhausted in spite of all available means being used to purify the air . . . With the air conditioning shut down, the temperature within the boat went to a high figure. A temperature of 125°F. was reported in the maneuvering room. All of the men were nauseated and 75% were vomiting. Both CO2 absorbent and oxygen were used but despite that, the air was very foul towards the end. . . Headaches were severe. A good many men were in a state of physical collapse . . . towards the end, stations were manned by volunteers who had the stamina and will to move and think. Many of the others were past the stage of caring what happened". In PUFFER's case, as in many others, it is impossible to differentiate between the relative deleterious physiological effects of increased CO2, depleted oxygen, increased air pressure, and high humidity and extreme heat caused by lack of air conditioning. Any one of these causes acting alone is sufficient to cause discomfort.
21-8. Before submerging, whenever circumstances permitted, most Commanding Officers followed the practice of thoroughly ventilating their submarines so that the air within at the onset of the dive would be as pure and fresh as possible. In extreme cases, such as PUFFER's prolonged dive, the condition of the ship's atmosphere at the time of diving may be a major factor in determining the maximum possible time of submergence. According to Chapter 38, Bureau of Ships Manual, the established limiting concentrations for minimum safe breathing conditions of 17 per cent oxygen and 3 per cent CO2 will not be reached, assuming fresh air to start with, until the expiration of a period of hours calculated by the following formula T = 0.04 V/N where T is the number of hours, V is the volumetric content of the submarine in cubic feet and N is the total number of men in the crew. By this formula, the limiting values for SS212 and SS285 Class submarines should be reached in about 18 hours. If time spent submerged under ordinary operating conditions is less than the period listed above, oxygen or compressed air replenishment and carbon dioxide purification should normally not be necessary. However, if it is predicted that the time of submergence will be greater than the limiting period, then air purification with CO2 absorbent should be resorted to when the CO2 concentration reaches 2% and oxygen replenishment should be undertaken at the end of the period.
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21-9. Study of some 89 cases of prolonged submergence where foul atmosphere was commented upon and recorded values of the CO2 and oxygen content of the air were reported, indicates that the limiting period of time allowed by the above formula is not always applicable to wartime operations. In 22 of the above reports, the actual limit of viability of the air was from one to six hours less than the calculated figure. Early use of CO2 absorbent should certainly be resorted to whenever long dives can be anticipated. It should be noted that a given weight of the CO2 chemical absorbent will always absorb a given amount of CO2 and that no absorbent can be saved by waiting for high CO2 concentrations.
21-10. An additional factor which often has affected the habitability of submarines operating under war conditions is the increase of internal air pressure usually experienced during prolonged dives due to the cumulative effect of small air system leaks, venting of tanks inboard and firing of torpedoes. Increases in barometric pressure as high as 12 inches (Hg) from these sources were reported in several cases. When not in contact with the enemy, the common practice during the course of a long dive, and often in conjunction with the revitalization of the air supply and use of CO2 absorbent, was to reduce the excessive pressure by pumping air from the ship's atmosphere into the air flasks with the high pressure air compressors. A much more effective measure, however, is to operate the low pressure blower, discharging the air into one or more ballast tanks and thence overboard through the ballast tank vents. Increase in air pressure can be annoying not only from the standpoint of headaches and decreased efficiency induced by the higher than normal pressure alone, but also because some members of the crew may not be able to equalize this pressure within their middle ears and will suffer consequent sharp pain and decreased hearing ability. In addition, increased air pressure will tend to accelerate the poisoning effects of CO2 and whatever other toxic gases may be present.1
21-11. In several cases, toxic or noxious gases have been released in our submarines as a direct or indirect result of war damage. When operating submerged, the military efficiency and even the survival of a submarine can easily be affected by the contamination of the atmosphere with objectionable or deadly gases since these, if present, cannot be ejected. Fires have been the principal source of such gases.2 Chlorine gas formation has been reported in several instances following the introduction of salt water into torpedo batteries or main propulsion batteries. HAMMERHEAD (SS364) on her fourth patrol reported "Battery compartment of torpedo flooded during attack, emitting chlorine gas into boat". PETO (SS265), while submerged and undergoing depth charge attack on her first patrol, detected chlorine gas in the after battery compartment. It was discovered that salt water had been introduced into the main battery from a leaking engine air induction drain and battery ventilation drain which were interconnected. Fortunately, only five cells received a small quantity of salt water and release of chlorine was slight. On GRENADIER's (SS210) fourth patrol,
1 See paragraph 22-15 and TANG narrative, paragraph 10-25.
2 See GRENADIER narrative, Section VIII, and SCAMP narrative, Section IX, for illustrations of the effect of combustion products from fires on personnel and ship operation.
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as the result of a depth charge attack, salt water leaked into the after battery sump from a watercloset that overflowed due to its sea valves jarring open. Sufficient chlorine gas was released from contact of this salt water with the battery acid accumulation in the sump to cause acute discomfort to all hands. Symptoms were aching joints, headaches, pains in throat and lungs, rasping cough, and some cases of vomiting. The efficiency of the whole ship's company was adversely affected for several days. GRENADIER's experience demonstrates the desirability of routine periodic flushing of battery sumps with fresh water and soda lime solution to prevent accumulation of acid. On S-27 and S-36, both of which went aground and were abandoned, salt water entered the battery compartments and chlorine gas was generated.
21-12. In a few instances, fumes from fuel oil leaking into the hull through inboard vents or leaking compensating and transfer lines have caused minor discomfort. For example, TUNNY (SS277), heavily damaged on her seventh patrol, reported "All hands had headaches from breathing oil fumes from the oil leaking into the boat from the No. 7 normal fuel oil tank".
21-13. The type of refrigerant used in air conditioning and refrigerating systems is a matter of much importance on submarines since, on several occasions, depth charge attacks have caused release of refrigerant gas through damaged joints and fittings. Freon 12 is currently employed for air conditioning and refrigerating purposes on U.S. submarines and is ideally suited for such use since it is non-inflammable, non-explosive, odorless and non-toxic in quantities up to 20 per cent by volume. No ill effects were reported in those instances where Freon escaped. An interesting example of what can happen through the use of less suitable refrigerants is the experience of the Dutch submarine HNMS O-19. 0-19 was heavily depth charged on the night of 9 January 1945, while operating under the command of ComSubsSoWesPac during her third war patrol, and was forced to the bottom by the first attack. While still on the bottom, another close depth charge attack was received, one of the most serious effects of which was to cause CO2 to leak from the engine room air conditioning system. The stern compartment and the engine room were immediately evacuated but in spite of closing all bulkhead watertight doors, CO2 reached the control room and made it necessary for personnel to evacuate to the conning tower, the CO2 being heavier than air. The pressure in the boat rose steadily due to internal air leakage from various air systems and accelerated the physiological effect of the CO2 on personnel. Escape breathing equipment (Draeger), fitted with soda lime containers, was used to absorb excessive CO2 content in areas of dangerous concentration. The telephones were out of action and personnel in the various compartments had no way of ascertaining what was going on in the other spaces. Two hours later, the boat was surfaced with the engine room still secured but was immediately placed on the bottom again when two enemy vessels were sighted close aboard. It was then decided to re-enter the engine room while submerged, ready the engines and then attempt to escape at high speed on the surface. A small party of men using rescue breathing equipment (DSEA) managed to enter the engine room and rig the engines for immediate starting. The engine room was found half flooded, the leakage
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occurring through sea valves which had jarred open during the last depth charge attack. Some men who removed their DSEA sets in order to reach valves located in confined areas were overcome by the CO2 All of the men in this party suffered after effects to some extent from CO2 poisoning. The ship was then surfaced and escaped without difficulty, the enemy having departed. Repairs were undertaken at Fremantle, W.A., at which time the air conditioning plant was converted for use with Freon gas.
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SECTION XXII
SUBMARINE ESCAPE NOTES
22-1. The problem of escape and rescue of personnel from sunken disabled submarines is currently undergoing review and study by the Navy Department. As projected submarines will be capable of operating at depths greatly in excess of 500 feet, it is evident that currently available escape devices, rescue chambers, search aids, and doctrine for their proper use, must be reconsidered as to their applicability for use at such depths. This is particularly apropos in view of the tragic war experience of TANG (SS306) where only six of some forty men were able to escape from underwater although the submarine was sunk in only 180 foot depth.1 It has become apparent that new devices and techniques must be developed before escapes from submarines disabled at relatively great depths will be feasible.
22-2 There are at present but three accepted methods considered practicable for our submarine service by means of which personnel can successfully transit from a sunken disabled submarine through the intervening water layer to the surface. The first and most obvious method is based on rescue by the use of a structural chamber designed to withstand hydrostatic pressure throughout its operating depth and which can be brought down from the surface to specially designed hatch openings on the disabled submarine below, enabling relatively safe group escapes. This instrument was developed by the U.S. Navy and is known as the "submarine rescue chamber". The second method calls for individual escape, personnel exiting from the disabled submarine through either a small intermediate enclosed air-lock or a skirted-type trunk built into the pressure hull, and then slowly ascending to the surface with the aid of a mechanical breathing device known in the U.S. Navy as the "lung". Rate of rise to the surface of the escaping personnel using this second method is regulated by ascending a line secured from the submarine to a surface buoy. An escape breathing apparatus has been used by all major navies and in the U.S. Navy a certain amount of "lung" training under simulated escape conditions is normally a mandatory requisite for all submarine service candidates. The third method may at the present time be considered an emergency variation of the second method. Individual escape is made through the same air-lock or trunk as in the second method but ascent to the surface is "free"; i.e., a rapid ascent is made without the use of mechanical breathing aids or ascending line of any nature, escaping personnel rising under the influence of their own buoyancy and swimming up. Although some instruction is given in this method of escape in the U.S. Navy, it has so far not been particularly emphasized or recommended and "free" training ascents have not been required due to preference for the "lung" escape and the probable training hazards involved in "free" escapes where large numbers of men are involved.
22-3. The escape problem on submarines is considerably increased by the necessity of having to confine escape structures and equipment
1 See TANG narrative, Section X.
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to those consistent with the required military characteristics of the ship. Space and weight considerations usually render it extremely difficult to achieve even the minimum desired military features on a new submarine design. Escape provisions are therefore naturally given secondary emphasis. Many workable schemes which would be decided improvements over existing escape arrangements could be devised if a submarine had no military mission. One such ideal but inadmissible proposal would be to design a portion or portions of the hull which could be detached and brought to the surface by the surviving members of the crew.
22-4. In the entire history of the U.S. Navy there are only two known instances of successful underwater escapes from sunken disabled submarines. SQUALUS (SS192) sank off the Isles of Shoals in 230 feet of water on 23 May 1939, when all compartments aft of the control room flooded through the engine air induction piping. The next day all of the 33 men who survived the initial flooding were removed through the forward torpedo room escape trunk by expeditious and skillful use of a submarine rescue chamber. The task was accomplished in four trips. TANG (SS306) was sunk off the coast of China in 180 feet of water on 26 October 1944 by the malfunctioning of one of her own torpedoes. Six men made successful individual escapes from underwater, one from the conning tower and five from the forward torpedo room escape trunk. The conning tower escape and one of the forward torpedo room escapes were "free". The remaining four were "lung" escapes. At least eight other men are known to have left the escape trunk but either died shortly after reaching the surface or were not seen again after leaving the trunk.
22-5. Since the experience of the U.S. Navy with underwater escapes, other than training exercises, is limited to the above two cases, it is necessary to turn to the experiences of other nations for further data. The British Admiralty Submarine Escape Committee has compiled information and statistics on every instance known to them of past submarine escapes of all countries. These records contain much interesting, and in some cases, detailed information. They serve to stress the difficult conditions usually attendant upon submarine escapes after damage and which in most instances have prevented a high percentage of successful escape completions. The escape problem on submarines can be considered in three phases as follows: (1) survival within the submarine after damage up to the time personnel actually exit from the hull, (2) survival during the ascent to the surface and (3) survival after reaching the surface until rescued.
22-6. According to the British records, of all the personnel who have been carried to the bottom in known cases of sunken submarines, a total of about 500 men are believed to have survived both the initial accident or damage causing the sinking and the subsequent primary flooding. Of these 500 men, a total of 32 were rescued from three submarines of such small size that the boats were lifted bodily by cranes;1
1 U-3, 18 January 1911; USS O-5, 29 October 1923; HDMS DYKKEREN, 10 October 1916.
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33 were saved by rescue chamber;1 and 46 were taken off a submarine sunk in shallow landlocked waters where raising the bow of the ship was comparatively simple and expeditious.2 Of the remaining 390 men who survived the initial accident, approximately 250 or 60% perished inside their respective submarines. It is probable that the principal cause of the majority of these deaths was CO2 poisoning, in some cases due to delaying the escape attempt too long,3 and in others to the accelerated poisoning effect of CO2 when present in atmosphere under high pressure.4 This latter condition occurs when flooding a compartment to equalize internal pressure with sea pressure to permit a skirted-trunk escape. Other known causes were drowning due to further uncontrollable or inadvertent flooding,5 drowning as a result of deliberately flooding a compartment to equalize internal pressure with sea pressure to permit skirted-trunk escapes,6 chlorine gas,7 and drowning within an air-lock type escape trunk.8 Of the 142 men who are known to have left their submarines on attempted individual escapes, 106 men or 75% reached the surface alive and survived until rescued. This represents only 27% survivors of the possible original 390. Of the 36 who left their ships on attempted escapes but did not survive, some are known to have reached the surface alive but subsequently died by drowning, exhaustion, or by prolonged immersion in cold water.9 The others died from various causes, among them being air embolism, asphyxiation, ruptured lung tissue due to failure to exhale during ascent, and drowning due to inhalation of water during ascent.
22-7. The statistics for these escapes, although not based on enough instances to be conclusive, indicate the following interesting and pertinent points:
(a) It appears that with present equipment and techniques the chance of survival by using the individual escape method decreases about 10% for every 30-foot increase in depth, until at 250 feet and beyond, the chance of survival is very small.
(b) The phase between the initial accident and the actual escape attempts is by far the most critical. Eighty-eight per cent of all subsequent deaths among personnel who survived the initial accident occurred during this period.
1 USS SQUALUS, 23 May 1939.
2 HMS K-13, 29 January 1917.
3 HMS THETIS, 1 June 1939, 95 men; U-51, World War I, 16 men; U-741 World War II, number unknown.
4 HMS UNTAMED, 30 May 1943, 36 men.
5 UB-57, World War I, number unknown; HMS STRATAGEN, November 1944, possibly 4 men.
6 U-767, World War II, 6 men.
7 U-859, World War II, 4 men.
8 HMS THETIS, 1 June 1939, 4 men.
9 Four 7-man CO2 inflated life rafts will be furnished to each active submarine as soon as available and the hull allowance lists have been modified accordingly. SEA FOX (SS402) conducted tests which demonstrated the practicability of ejecting such rafts from torpedo tubes, using torpedo impulse air. It is expected that deaths due to exposure and drowning subsequent to reaching the surface should be reduced by successful use of these rafts in conjunction with escape operations.
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(c) The advantage of rapid flooding over slow flooding when sea water must be admitted to a compartment to equalize internal air pressure with external sea pressure to permit escape through a skirted-trunk, is demonstrated by the fact that there were only 21% survivors after slow flooding whereas 66% survived when flooding was rapid. As would be expected, the figures also show that as the depth increases, a higher percentage of survivors results when the escape compartments are flooded rapidly rather than slowly. This is particularly marked at depths greater than 100 feet.
(d) The hazard of the ascent itself, particularly when made by well trained personnel, is relatively minor for depths up to about 200 feet. Of all the men who left their submarines on individual escape attempts, either with or without an apparatus, probably less than 10% perished during the actual ascent.
(e) Well over half of the survivors made "free" ascents, either entirely without breathing apparatus or with such apparatus but using it as a buoyancy bag only due to maloperation or defective parts.
22-8. When circumstances permit use of a submarine rescue chamber, this method is usually to be preferred since it is likely that a higher percentage of successful rescues will be obtained and no individual effort is required on the part of the men trapped within the sunken submarine. However, the following conditions must exist:
(b) Its exact position on the bottom must be definitely established.(a) The fact that the submarine has sunk must be made known to cognizant rescue authorities within a short period after the sinking occurs.
(c) The depth of water must not exceed the operating depth of the rescue chamber, or with present apparatus, the depth at which divers can descend to attach a downhaul cable.
(d) A rescue chamber, trained crew and rescue vessel must be so located as to reach the scene quickly.
(e) Tides, currents and weather must be favorable for diving and rescue chamber operations.
(f) The survivors within the submarine must be able to reach an escape station fitted for use of the rescue chamber.
(g) List and trim of the submarine as it lies on the bottom must be such as to permit proper access to the escape station attaching surface.
In time of war, conditions (a), (b) and (d) will usually not be met.
22-9. Presently available rescue chambers and operating gear are not considered suitable for rescue of submarine personnel at depths much exceeding 450 feet. This is due to the fact that, although the
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structural design of the latest chambers provides for a rated operating depth of 550 feet, divers must attach the chamber downhaul cable to the submarine and 450 feet is considered to be about the maximum possible working depth of divers using present diving techniques under ideal conditions. Development is currently underway on a proposed submarine messenger buoy which when released from a sunken submarine will float a light high strength rescue chamber downhaul cable from depths as great as 850 feet. Investigation shows that the present rescue chambers can be altered for use at 850 feet with but minor modifications. This scheme will eliminate the use of divers and the need for complicated mooring of the rescue vessel.
22-10. When use of the rescue chamber is not feasible, due to any of the conditions enumerated in paragraph 22-8 above, the only hope of survival for the crew members will then lie in individual escape attempts. The submarine escape device or "lung" was developed by the U. S. Navy in 1929 to provide individual crew members with a reasonably safe means of escape from disabled sunken submarines. An extensive program of indoctrination and training of submarine personnel in its use, capabilities and limitations was undertaken. In order to provide "lung" training at substantial depths, escape training tanks were constructed at the U.S. Naval Submarine Bases at New London and Pearl Harbor in 1930 and 1932, respectively. These towers have an overall height of 134 feet providing a vertical column of water 100 feet high and 18 feet in diameter with escape locks or compartments simulating those on submarines located 18, 50 and 100 feet from the top of the tank. This permits escape training under conditions approximating those existing in similar depths at sea and with identical pressure factors. With the advent of World War II the program was expanded tremendously in an effort to provide "lung" instruction for all men training for the submarine service, although a considerable number of men unfortunately did not have access to such training. Since inception of the program, over 46,500 men have made the 18-foot ascent, over 29,800" men have made the 50-foot ascent and over 6,300 men have made the 100-foot ascent.
22-11. A study of TANG's experience, where only 5 men or 10% of a possible 45 men trapped in the forward torpedo room successfully escaped, indicates that an increase in the speed of operation of the trunk would have enable more personnel to make the attempt. The average time between successive escape parties was from 45 minutes to one hour. This compares very unfavorably with recent shallow water escape exercises conducted by SIRAGO (SS485) on 28 and 29 August 1946. The submarine was submerged to a keel depth of about 70 feet and a total of 35 officers and men made individual escapes through the forward torpedo room air-lock, entering the trunk in groups of
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3 and 4. The average time for each escape cycle, i.e., the time required for each party to enter the trunk, flood, escape, and for subsequent draining and readying of the trunk for the next party, was about 15 minutes. The minimum cycle time was 9 minutes and the maximum 26 minutes, this latter time including rigging of an escape buoy, ascending line, and streaming of a Mark 4 rubber boat from the escape trunk. During these exercises three men experienced difficulty with their "lungs". One who had had previous instruction in "free" escape made the ascent successfully without his "lung". The other two returned to the trunk.
22-12. The need for continued and rigorous "lung" escape instruction for all men and officers of the active submarine service, including periodic refresher courses, is clearly indicated if reliance is to be placed on this method in the future. In addition, more emphasis should be placed on the "free" escape method. Familiarity with this type of escape certainly holds the possibility of saving lives in many conceivable instances and will in addition induce more confidence in the "lung" type of escape.
22-13. It is pertinent to consider whether or not more lives would have been saved on TANG had the forward torpedo room been fitted with a skirted trunk, as in the after torpedo room, instead of the air-lock type escape trunk. In TANG's case there are certain advantages which could be claimed for either type due to the fact that the depth of 180 feet was only slightly in excess of that beyond which the skirted trunk is ordinarily not considered suitable.
22-14. The principal advantage of the skirted trunk is that once the escape compartment has been flooded so as to equalize internal air pressure with sea pressure, and the trunk outer hatch has been opened, individual escapes can then proceed in rapid succession with but a few seconds interval between departures. The technique is simple and requires but little effort. All personnel know what is going on at all times. If a man happens to "freeze" in the trunk he can immediately either be forcibly ejected or drawn back into the compartment. This procedure would have eliminated the long delays between successive escape parties which were so disastrous for TANG and it is quite possible that more men would have been forced to make the escape attempt and therefore more would have reached the surface alive.
22-15. The principal disadvantages of the skirted trunk for escape at great depths are as follows:
(a) During and after the period of flooding the escape compartment to equalize internal pressure with the sea, personnel within will be subject to nitrogen narcosis, CO2 poisoning, and the deleterious effects of other noxious or toxic gases which may be present, such as chlorine, carbon monoxide, smoke, etc., since these gaseous components will be under higher than normal pressures. For example, the concentration of CO2 which can be tolerated is inversely proportional to the absolute pressure; at an air pressure equivalent to 350 foot depth of water, three per cent CO2 content by volume, which would be harmless at atmospheric
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pressure, will have about the same physiological effect as thirty per cent CO2 content by volume at atmospheric pressure and will cause death in a very short period of time. Approximately the same holds true for nitrogen and noxious or toxic gases. At pressures corresponding to depths greater than 150 feet, this effect may become so pronounced that personnel can remain conscious only for very limited periods of time, particularly if the atmosphere initially contains smoke, toxic gases or higher than normal portions of CO2. Increasing the percentage of oxygen in the air may also introduce the possibility of oxygen poisoning at high pressures.
These factors are considered to render the skirted-type trunk useless for escape at depths much below 150 feet for the average person, although from a standpoint of simplicity there is much to be said in its favor. The principal and very great advantage of the air-lock type escape trunk is that it enables rapid compression of the escape party to sea pressure and permits remaining personnel within the ship to stay at pressure near normal while awaiting their turn.
22-16. In considering problems involved in the successful execution of individual escapes, the debilitating effect on mind and body of some or all of the following possible conditions must constantly be borne in mind:
(a) The shock effect on personnel of the initial accident or damage which caused the sinking.
(b) The presence of seriously injured or mentally deranged personnel.
(c) Lack of lighting.
(d) Exposure to heat or cold and excessive humidity.
(e) Continued breathing of poor or toxic atmosphere.
(f) Excessive trim or list on the submarine which may render even normal movements difficult.
22-17. It is clearly evident in the light of available experience that the first requirement of any escape method is that it be simple and so calculated as to obtain the highest percentage of survivors. It is also apparent that present methods are not satisfactory at deep depths.
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22-18. The British are currently investigating the use of a small cylindrical one-man escape chamber fitted with hatches top and bottom and provided with a mechanical apparatus permitting forced ejection of a man from within the trunk if necessary. This trunk would be intended for use in conjunction with both "free" and "lung" escapes. The system is believed by the British to have the following advantages:
(a) Simplicity.
(b) The escaping man has no control over the operation once he enters the trunk, and whether dead, unconscious or confused, he can be forcibly ejected to make room for the next man.
(c) A total trunk operation cycle time of about 4 or 5 minutes appears possible.
(d) Brief subjection to air at high pressure minimizes the chance of nitrogen narcosis, CO2 poisoning, air embolism and caisson disease.
22-19. In this country, as stated previously, further research and development studies are underway by the Navy Department in an effort to improve submarine search and rescue equipment. One line of investigation which may prove of great value is the use of helium-oxygen mixtures in conjunction with a breathing device and which possibly may permit use of the skirted-type trunk for escape at all depths up to the collapse depth of the submarine itself. The "flooding up" stage, which is a necessary preliminary to a skirted-trunk escape, is particularly critical due to the inability of average individuals to remain conscious for even short periods when breathing a normally proportioned air mixture at high pressure. For example, it is considered likely that if an escape compartment were slowly flooded at a depth of 350 feet, most normal personnel within would be incapacitated or unconscious before internal pressure had been equalized with sea pressure. It has been determined that the air component chiefly responsible for unconsciousness when breathing under high pressure is the nitrogen portion. When the nitrogen is replaced by helium, unconsciousness does not occur at least up to 500 feet and there is reason to believe that unconsciousness will not occur at depths considerably greater than 500 feet inasmuch as the intoxication preceding coma does not occur to any extent even at 500 feet when using helium. From a physiological point of view, the "lung" itself is believed to be capable of permitting safe ascent from depths considerably greater than 500 feet, providing the proper breathing mixtures can be continuously provided and decompression rules are carried out.1 Divers using helium-oxygen mixtures, for example, have worked
1 "Lungs" have been used with normal air mixtures at simulated depths as high as 354 feet in the mine tank of the U.S. Naval Gun Factory, Washington, D.C. Actual escapes were made in the open sea off Key West, Florida, at depths up to 200 feet from the torpedo room and motor room of S-4 (BuC&R ltr. No. L9/P-(14) (ME)N/C; EN7/A2-11 of 10 September 1929);
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at a depth of 440 feet in conventional diving suits.1 Initial inflation of "lungs" with helium-oxygen mixtures would also facilitate and may even be mandatory for air-lock escapes at extreme depths. The depth limitation of the present "lung" for individual escape, using oxygen alone, is considered to be about 200 feet for normal men, and it is believed that helium-oxygen mixtures should be used at all depths greater than 200 feet.2
22-20. Other projects which are currently being investigated and which may prove of practical value for locating sunken submarines and for escape therefrom are:
(a) Development of a radio beacon which can be ejected from a signal ejector on a sunken submarine to give automatic distress warning signals useful for homing by searching vessels.
(b) Development of a noise source, such as a sonar test target with increased power, suitable for sonar homing.
(c) Dye markers which can be ejected from a signal ejector to indicate location.
(d) Development of a short range emergency-powered underwater sonar telephone system which can be used for communications during rescue operations.
(e) Development of a messenger buoy and modification of present rescue chambers for operations at great depths, as mentioned in paragraph 22-9.
(f) Modification of the "lung" to provide a collar for buoyant support of the head after reaching the surface (similar to German apparatus), in order to lessen the chance of drowning if the wearer becomes unconscious after surfacing.
(g) Provision of equipment for mooring submarine rescue vessels in 850 feet of water.
(h) Development of a simple battery-powered two-way voice communication system between the escape trunk and compartment below. The experiences of TANG (SS306) and SIRAGO (SS485) demonstrated the inadequacy of attempting communications by hammer taps or other such means.
(i) Experimental investigations in "free" escape techniques.
1 U.S. Navy divers reached 440 foot depth without suffering adverse effects while inspecting 0-9, lost with all hands on 20 June 1941 off the Isles of Shoals. A 90/10 helium-oxygen mixture was used.
2 Helium-oxygen mixtures can be quite easily provided for submarine bow and stern compartments in a manner similar to that now used for oxygen stowage.
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SECTION XXIII
CONCLUSION
23-1. In World War II the capacity of our submarines to survive intense underwater explosive attacks without receiving damage of serious nature was clearly established and continuously increased during the course of the war. This was accomplished principally by instituting a comprehensive shock protection program for all submarines in service and under construction and by increasing the scantlings of the pressure hulls on more recent classes to permit greater operating depths.
23-2. The damage experiences of KING FISH, TUNNY, SALMON, SCAMP, HALIBUT and REDFISH represent instances where considerable permanent pressure hull deformation was sustained by submarines on which all or a substantial portion of the shock protection program had been accomplished. On these vessels, vital equipment was in general not affected seriously although further improvement in the resistance to damage of certain components, particularly piping and electrical items, was clearly indicated.
23-3. From the standpoint of vulnerability to non-contact underwater explosive attack, the ideal submarine is one having a pressure hull of maximum efficiency for the allowable weight of the shell and framing, free of stress raisers, and with all other equipment, appurtenances, systems, etc., of such strength or so well protected from shock that the hull itself will be destroyed before other vital components sustain serious damage. In other words, the ideal submarine could only be destroyed by causing collapse or holing of its pressure hull. This desirable condition has been closely approached on modern U.S. submarines. It is significant to note that only five reports in the entire Japanese list of 468 "positive" sinkings of U.S. submarines referred to in Appendix II mention partial or complete surfacing of a submarine having occurred while it was under attack, none of which can be related to a known sinking, whereas over 200 reports contain mention of sighting large quantities of oil, frequently accompanied by air bubbles and debris, after attacking purported submarines. These figures, although admittedly based on incomplete information, would seem to indicate that destruction of our submarines occurred through rupture of their pressure hulls since it is reasonable to assume that even though a submarine were disabled so that it could no longer operate submerged, sufficient air should remain to permit surfacing.
23-4. In the final analysis, it is apparent that the survival of many of our submarines after receiving war damage was due in very large part to the damage control efforts of their personnel. The long standing requirement that all hands in the submarine service know their ships thoroughly has paid priceless dividends in terms of human life and the successful prosecution of the war.
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23-5. As a result of the great improvements made in anti-submarine warfare during the past few years and prospective radically new developments in propulsion machinery, the concept of the submarine of the foreseeable future has undergone drastic change. U.S. submarines as developed for World War II were designed primarily for employment as submersible surface raiders with high surface speed and low submerged speed. This type of submarine was remarkably successful in operations against the Japanese and fortunately suffered a relatively low rate of attrition due to the marked ineffectiveness of the enemy anti-submarine effort. The present trend of U.S. submarine design is in the direction of smaller, high submerged speed attack submarines capable of operating at extreme depths. Other types of submarines for special missions are also under consideration. With the advent of a suitable propulsion plant capable of delivering great power for sustained operations submerged, the submarine will become a true submersible.
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APPENDIX I
Briefs of War Damage Incurred by U.S. Submarines
During World War II
1. A survey of war patrol reports and other information available to the Bureau indicates that during World War II there were 110 separate instances in which United States fleet type submarines survived damage from attack by either enemy or friendly forces where the damage received may be considered as more than negligible or where the circumstances of the attack or the nature of the damage has been considered of sufficient interest to warrant reporting. Briefs of each of these damage cases are presented on the following pages of this Appendix. Receipt of information with substantiating documents in correction of any of the data which may be found in error will be appreciated. Address Code 424, Bureau of Ships.
2. This Appendix together with Appendix II, the latter being a tabulation of United States submarine losses, summarize presently available information on the war damage experiences of U.S. Navy submarines throughout World War II. Section II contains a statistical summary of the types of weapons causing the damage in the 110 separate instances of damage, and a list of the governing damage item or items which forced termination of 49 war patrols.
3. Seven of the 110 damage cases listed in this Appendix have been described in detail in the body of this report.
4. Appendix I and Appendix II supplement the series of four confidential publications prepared by this Bureau which summarize the war damage to U.S. battleships, carriers, cruisers and destroyers for each of the four years of the war.
5. The following briefs have been arranged in as close adherence to chronological order as could be made without continuing the "remarks" column of any brief to another page.
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
SEADRAGON (SS194) |
12/10/41 |
Navy Yard, Cavite, P.I. |
Bombs - 2 |
SEADRAGON was berthed inboard of SEALION (SS195) at Navy Yard, Cavite during Japanese high level bombing attack. Fragments from two small bombs which made direct hits on SEALION, one amidships and one aft, caused considerable structural damage on SEADRAGON. Conning tower was holed in four places, varying in size from 3 to 6 inches in diameter. Most of bridge and conning tower wiring was carried away or punctured. Conning tower deadlight, port side, was blown out. Radio antenna trunk was torn open. NFO No. 1 and MBT No. 3F were punctured by many small fragments. One large fragment caused dent about 6 inches deep at frame 155 and slight tear in pressure hull plating. Superstructure plating amidships and conning tower fairwater were riddled in numerous places. Engine air induction piping was punctured over after engine room. Open paint pots on deck ignited, causing fire damage topside. |
SARGO (SS188) |
(3rd) |
Off Western Australia |
Bombs - 2 |
Received two bombs from RAAF two-engined bomber. First bomb was received shortly after diving, causing no damage but forcing ship to assume large down angle. Descent was checked at 170 foot depth by stopping motors and blowing bow buoyancy and forward group of main ballast tanks. Ship then broached and received second bomb close aboard conning tower while at about 50 foot depth. Main propulsion power was temporarily lost for reasons not stated. Both periscope exit windows and prisms were shattered and both periscope tubes flooded. After bulkhead of conning tower was slightly deformed, causing after bulkhead door to leak seriously at depths above 80 feet. Electrical panels and engine order telegraphs in conning tower were grounded by flooding. Three porcelain water closet bowls fractured. High pressure air system developed two leaks. Lighting power was lost and numerous bulbs were broken. Many gauges meters and instruments were deranged or broken and other minor damage occurred. Ship was already enroute to base but otherwise would have had to terminate her patrol due to periscope damage. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PERMIT (SS178) |
3/17/42 |
Tayabas Bay, P.I. |
Depth Charges - 14 |
Depth charged by three Japanese destroyers shortly after submerging and on way deep. Conning tower door gasket was cut by excessive pressure on knife edge of door seat and partially bulged out, resulting in considerable leakage into conning tower. Other damage was minor. Ship remained on patrol. |
SEAWOLF (SS197) |
3/31/42 |
Off Christmas Island, Indian Ocean |
Depth Charges - 25 |
Depth charged by Japanese destroyers and/or cruisers over 7 1/2 hour period. First attack tripped overload relays on after battery negative bus. This caused main power bus contactor and main battery bus contactor to open, cutting off power to main motors. Ship dropped from 200 to 270 foot depth before power was restored. Relays and contactors were then blocked closed with wooden wedges. Engine lube oil cooler coils developed leak, allowing sea water to enter main engine sumps since circulating water sea valves were not tight. Gyrocompass repeaters and radio transmitters were disabled. Cable stuffing glands in conning tower and starboard shaft stern tube leaked heavily. Trim line ruptured in forward torpedo room, and as emergency measure, forward trim tank was blown and flooded through torpedo tube drain and vent valves. Ship remained on patrol. |
PORPOISE (SS172) |
5/8/42 |
Off Ceram, Moluccas |
Depth Charges - 4 |
Depth charged by Japanese escort while at 170 foot depth. Stern planes lost power and jammed temporarily. Hull valve to NFO No. 3 backed off and relief valve in after torpedo room opened, admitting fuel oil to that compartment. Elbow in blow line to NFO No. 3 was ruptured. Two battery jars cracked. Ship remained on patrol. |
GRAMPUS (SS207) |
5/17/42 |
Off Truk |
Gunfire - 1 |
Received one 3 or 4.7 inch shell hit in after portion of conning tower fairwater. See Section XII for detailed account. Ship remained on patrol. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
NAUTILUS (SS168) |
6/28/42 |
Off Central Honshu |
Depth Charges - 11 |
Depth charged by Japanese cruiser. Five close charges were received while passing 200 foot depth on way down. Rudder operation became very noisy as result of depth charging and starboard ram moved in jerks, either due to air in hydraulic system or jammed packing. Three pressure hull hard patches developed leaks. Bow plane indicator housing in anchor windlass room fractured. Electrical cables were forced into hull and in several cases streams of water entered hull around packing glands. Silver-soldered joints of Nos. 4 and 10 high pressure air banks developed leaks. Silver-soldered joints in hydraulic line to No. 7 MBT parted and several other hydraulic lines leaked. Both stern tube stuffing boxes developed excessive leakage. Outboard main engine exhaust valves leaked, allowing external exhaust piping to flood. Plastic coating in variable tanks flaked loose and particles appeared in forward torpedo tubes from WRT tank. Miscellaneous other minor damage occurred. Ship remained on patrol. |
THRESHER (SS200) |
7/9/42 |
Off Kwajaleln |
Bomb - 1 |
Bombed by unidentified Japanese aircraft while passing 80 foot depth. Serious air leakage developed at high pressure air bank in No. 5 MBT. Main vent valves had been left open and consequently air bubbled to the surface through vent riser, enabling enemy planes and surface escorts to track THRESHER, the sea being glassy calm. Several more bomb and depth charge attacks were made but resulting damage was minor. Ship was also hooked by small grapnel for ten minutes. Ship remained on patrol. |
PICKEREL (SS177) |
8/12/42 |
Off Marianas Islands |
Depth Charges - 4 |
Depth charged by Japanese escort while at 230 foot depth. Tubes in Nos. 1 and 2 main engine heat exchangers were ruptured. Cooling water hose to No. 2 main engine outboard exhaust valve carried away. Hull stop valve for hose line was secured but not until spray had entered No. 2 main generator casing through flexible coupling and soaked field windings. Fresh water rinse and slow drying by application of heat restored generator to service. Ship remained on patrol. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
FLYING PISH (SS229) |
9/2/42 |
Off Truk |
Depth Charges - 8 |
Depth charged by Japanese PC. Received three charges while passing 160 foot depth and 5 charges while at 250 foot depth. Unstated damage caused leakage into after trim tank of 8000 lbs. hourly at 300 foot depth. Stern planes were forced out of alignment, requiring two men to operate them with difficulty by hand power. Cables on No. 1 periscope parted. This periscope was housed at limit switch and dropped 4 inches to bumper. Engine air induction piping and forward battery soft patch leaked. Boat was unable to maintain satisfactory trim or run silent. Patrol was terminated. |
SCULPIN (SS191) |
9/28/42 |
Off New Britain |
Depth Charges (No. not reported) |
Depth charged by two Japanese escorts while at about 250 foot depth. First close charges caused temporary loss of main power by jarring control cubicle overload relays open. These were reset by hand and power was regained ten seconds later. Stern planes lost power and stalled on 15° dive position with boat at 280 foot depth. By quickly shifting to hand control, the planes were operated again before serious effects on depth control resulted. Contact arm porcelain insulator in governor control for No. 1 generator engine fractured, causing full ground on generator armature circuit. Various leaks throughout boat caused increase of 20,000 lbs. weight. Maintained depth by running at 2/5 speed ahead on both shafts with 10° to 12° rise angle on boat. Gauge glass on hydraulic replenishing tank fractured, causing loss of oil in tank. Knife edge on conning tower door seat cut through door gasket but only minor leakage resulted. Refrigerating compressor motor in pump room flooded out, causing loss of all stores In cold room. Numerous valves jarred open, gauges shattered, light bulbs and fixtures broke and miscellaneous other items of minor damage occurred. Temporary repairs were made and ship remained on patrol. |
TROUT (SS202) |
10/5/42 |
Off Truk |
Bomb - 2 |
Received bomb from Japanese aircraft while at 58 foot depth just as periscope was being lowered. Second bomb was received shortly thereafter while passing 80 foot depth on way down. Both Nos. 1 and 2 periscopes were put out of commission. The upper windows were shattered, upper prisms cracked, control wires jammed and periscope tubes flooded. No other damage was reported. Patrol was terminated due to periscope casualty. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
NAUTILUS (SS168) |
10/12/42 |
Off Northern Honshu |
Depth Charges - 15 |
Depth charged by AMAGIRI Class Japanese Destroyer. Majority of damage sustained was from one pattern of 5 charges dropped close overhead while NAUTILUS was running at 250 foot depth. Threaded high pressure air piping connection at forward separator started to leak. Rudder post packing jammed, causing rudder to groan and seize. Torpedo tubes Nos. 8 and 10 flooded through muzzle door gaskets. Impulse air system for deck tube No. 8 developed external air leak to sea. Bellows on pitometer log ruptured. Leak developed between NFO No. 5 and FBT No. 4B. Water seal gaskets on 6-inch deck gun were crushed. Bow plane tilting shaft clutch disengaged three times on close charges. No. 3 main Diesel engine governor jammed and engine had to be run by hand control for four hours. Port main motor bearing oil seal packing jarred loose, allowing oil to leak. Contacts for No. 1 lighting motor generator and port main motor ventilation blower jarred closed, starting both units. Optical systems of both periscopes were deranged. Ship's supply ventilation inboard hull flapper valve was misaligned, causing difficult operation. Numerous gauges, meters, instruments, etc., were broken or deranged and other minor damage occurred. Ship remained on patrol. |
WHALE (SS239) |
10/30/42 |
Off Southern Honshu |
Depth Charges |
Depth charged by Japanese OTORI Class torpedo boat. First close charges were received while passing 150 foot depth. Boat then leveled off at 300 foot depth but engine air induction, ship's supply ventilation and battery outboard exhaust piping topside completely flooded, causing increase in weight overall and aft. Inboard induction flapper valve in engine room was distorted and leaked badly. Boat assumed 15 up angle and started to settle. Up angle was reduced to 5° by sending 50 men to forward torpedo room. Depth control was regained at 360 feet and maintained thereafter by occasionally increasing speed and by blowing after trim to sea. These actions enabled the enemy to retain contact and depth charging by their escorts and and planes continued at various intervals for three hours. Motor room bilges flooded from excessive leak through starboard shaft stern tube packing. Starboard shaft developed pronounced swishing and squealing above 95 rpm, indicating misalignment. Other minor damage occurred. Patrol was terminated. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
GRAYLING (SS209) |
11/6/42 |
Off Truk |
Bombs - 3 |
Bombed by unidentified Japanese aircraft while at periscope depth. High pressure air piping developed leaks in after battery well and after torpedo room. Radio antenna trunk flooded and all antennae were knocked down. No. 2 periscope optical system was deranged. Gaskets on MBT Nos. 5A and 5B spring loaded vent valves were dislodged. Miscellaneous other minor damage occurred. Ship remained on patrol. |
TAUTOG (SS199) |
11/11/42 |
Makassar Strait |
Depth Charges - 11 |
Depth charged by Japanese escort while at about 250 foot depth. Cast iron plug in auxiliary engine circulating water sea valve body blew out and bilges flooded to depth of two feet before gaining control with drain pump. Ventilation supply blower shifted out of alignment. Stern planes and rudder developed high noise level. Bow plane tilting and rigging motors grounded. Numerous external electrical cables pushed through pressure hull packing glands, some by as much as one foot. QC sound head grounded internally and JK head was rendered insensitive. Miscellaneous other minor damage occurred. Patrol was terminated. |
SEAL (SS183) |
11/16/42 |
Off Palau Islands |
Ramming |
While at 61 foot depth and only twelve seconds after firing torpedoes at a Japanese freighter, SEAL was run down by a second Japanese cargo ship which passed directly overhead and damaged the periscopes, radar, and their supporting shears. Boat rose from 61 feet to 55 feet due to suction effect and hung there for nearly a minute before starting down. No. 2 periscope, which was fully extended, was bent nearly horizontal at top of shears. 3D radar mast was also bent over in same direction. No. 1 periscope could not be operated due to misalignment of upper bearings. No. 2 periscope housing was broken off level with top of housing for No. 1 periscope. No other damage occurred. Patrol was terminated. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
SNAPPER (SS185) |
11/24/42 |
Off Northern Solomons |
Bombs- 3 |
Received one large and two small bombs from unidentified Japanese aircraft while at periscope depth. Six minutes later, while running at 200 foot depth, 18 depth charges were dropped by Japanese destroyers. Bow buoyancy and MBT Nos. 2B and 2D vent valve gaskets were blown out. Low pressure blow line to FBT Nos. 5 and 6 ruptured. Light bulbs were broken throughout ship. Miscellaneous other minor damage occurred. Ship remained on patrol. |
STINGRAY (SS186) |
12/10/42 |
Off Northern Solomons |
Bombs - 2 |
Japanese float plane dropped two bombs just as No. 2 periscope (high) broke water for observation. Sea was glassy smooth. Concussion or possibly fragment of bomb shattered glass over periscope object prism, allowing periscope to flood and rendering it inoperative. No other damage occurred. Patrol was terminated due to this damage. |
AMBERJACK (SS219) |
12/20/42 |
Off Northern Solomons |
Depth Charges - 6 |
Depth charged by Japanese destroyer while at 250 foot depth. Head window of No. 1 periscope was shattered and upper prism of No. 2 periscope was chipped. SJ radar mast was thrown out of alignment. MBT No. 1 vent line was sprung and leaked steadily at periscope depth. Other minor damage occurred. Ship remained on patrol. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PIKE (SS173) |
1/14/43 |
Off Ichie Saki, Southern Honshu |
Depth Charges - 69 |
Severely depth charged by several Japanese destroyers over 8 hour period. First 3 charges detonated beneath ship while passing 65 foot depth on way down. Over 40 charges were then received during next hour while running at about 330 foot depth. Main propulsion power was momentarily lost when first depth charge tripped main motor overload relays. Flame and smoke issued from control stand. Brush rigging shifted 5 inches on No. 2 main motor. Dowel pins came loose and brushes chattered on all main motors. Pump room auxiliary power circuit breaker tripped open. Impulse air system leaked heavily both internally and externally. Starboard stern tube developed serious leakage, filling motor room bilges and flooding starboard circulating water pump and standby lube oil pump motors. Leakage through main engine exhaust valves and at flanged and silver brazed joints in main engine circulating water lines flooded engine room bilges and grounded No. 1 main generator blower motor. Main vent values fluttered with each close charge and developed numerous leaks. Trim pump motor controller starting coil dropped out of position and pump could only be operated by holding coil In place by hand. Over half of all light bulbs broke throughout ship. Many electrical grounds occurred in auxiliary machinery motor and controller circuits, i.e. systems, bridge instruments, etc. Numerous valves opened. Gauges and meters were broken or deranged. Muzzle doors were sprung on several torpedo tubes, allowing tubes to flood, and stop bolts and gyro spindles were bent. Plastic composition in variable tanks was shaken loose and large pieces were found in both the forward and aft torpedo tubes. Six hours after initial attack, PIKE went to periscope depth but was promptly bombed by Japanese plane and again went deep. Large air bubbles were noted at this time rising to surface from impulse system forward and aft. Throughout the entire period the boat was heavy overall and depth control was maintained by running at standard and full speed with hard rise on bow and stern planes. Maximum depth reached was 365 feet. Upon finally evading the enemy PIKE surfaced and cleared area on all four main engines. Patrol was terminated. |
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NAME DATE |
PLACE |
SOURCE |
REMARKS |
SILVERSIDES 1/18/45 (SS236) (4th) |
Off Central Carolines |
Depth Charges |
Depth charged while at deep submergence by Japanese minelayer or small destroyer. First barrage dislodged gasket from safety tank vent valve and shortly afterwards, when it became necessary to put a bubble in safety tank to maintain depth control, the air escaped through the vent to the surface, disclosing ship's location to enemy. The escorts promptly delivered another attack, this time quite close. Crew's head flushing line ruptured in FBT No. 5 and studs broke on blank flange in FBT No. 3, allowing considerable fuel oil to leak to sea. Japanese ZEKE followed oil trail for 45 minutes and finally attacked with depth bomb but missed SILVERSIDES by 4000 yards. Air vent opened on hydraulic line to engine induction outboard valve, causing valve to later slam shut when running surfaced on four engines. Sea valve leaked over No. 1 main generator terminals, later caused explosion and fire. Pipe plug blew out and nipple broke on two circulating water lines. Valves backed off, instruments were deranged, lights broke, etc. Damage incurred from this depth charging was a factor in early termination of patrol. |
SPEARFISH 1/19/43 (SS190) (7th) |
Off Gilbert Islands |
Bombs - 2 |
Bombed by unidentified aircraft while passing 140 foot depth. Several main motor brushes and spring assemblies were dislodged from their holders. No. 2 periscope upper limit switch derangement caused 230 volt ground. Steam-tight lamps in conning tower shattered. Water closet porcelain bowl was broken. Main engine outboard exhaust valves, which had previously been leaking excessively, were effectively seated. Gaskets for safety tank and MBT No. 4 main vent valves were blown out. Miscellaneous other minor damage occurred. Ship was enroute Pearl Harbor from patrol. |
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NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
GUDGEON (SS211) |
1/26/43 (6th) |
Banda Sea |
Depth Charges - 8 |
Depth charged by Japanese SC while running at 315 foot depth. Pressure hull was slightly dished inward between frames 118 and 119 in after torpedo room. External high pressure air leaks occurred at bank No. 2 and internal leaks occurred at bank No. 4. Starboard shaft and propeller became noisy and strut bearing developed squeal. Port stern tube leaked excessively and vibrated. QC sound gear shaft was forced out of alignment and chattered. Emergency fresh water tanks split seams and lost water. Gyro spindles were bent on several torpedo tubes. Leak occurred at brazed joint on main engine lube oil line. Hydraulic leak started in piping to stern planes. Gyro follow-up system grounded at damaged panel. No. 2 periscope optics were slightly deranged. Radio antennae insulators broke. Leak occurred between NFO No. 2 and MBT Nos. 2A and 2B. Ship remained on patrol. |
GROWLER (SS215) |
2/7/43 (4th) |
Off New Britain |
Collision & Machine Gun Fire (13mm) |
Collided with large Japanese gunboat and received subsequent close quarter enemy machine gun fire. Severe damage resulted to bow structure. See Section XIII for detailed account. Ship terminated patrol. |
SWORDFISH (SS193) |
2/7/43 (7th) |
150 Mi. North of New Ireland |
Aircraft Strafing (.50 cal.) |
Strafed by .50 cal. AP projectiles from U.S. Army B-17 bomber which approached SWORDFISH from 20° on the bow at an altitude of about 500 feet. SWORDFISH made a quick dive but received about 20 hits in bridge, conning tower fairwater and superstructure. Damage was as follows: (a) forward engine room access hatch skirt was struck by one projectile which did not penetrate completely but cracked the plating, causing minor leakage into boat; (b) pressure proof battery exhaust ventilation piping was punctured forward of conning tower, causing external system to flood completely; (c) one puncture occurred in low pressure blow line to MBT No. 3; (d) one puncture occurred in MBT No. 2A vent riser; (e) several projectiles ricocheted from top of conning tower pressure plating, causing nicks about 1/16 inch deep. Patrol was terminated. |
--260--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
BLACKFISH (SS221) |
2/19/43 |
Bay of Biscay |
Depth Charges - 9 |
Depth charged by two German converted trawlers while going deep. Conning tower after bulkhead door frame was cracked, causing serious leakage into conning tower. Upper flanges of MBT Nos. 1 and 7 vent risers leaked into torpedo rooms. Engine air induction piping developed considerable leakage as drains showed full stream. Ship went to bottom in 368 feet of water until enemy departed. Patrol was terminated due to conning tower door damage. |
RUNNER (SS275) |
2/19/43 |
Off Palau Islands |
Bomb - 1 |
Received one bomb from unidentified Japanese aircraft while firing torpedoes at periscope depth. Bomb detonated to port, close aboard conning tower. Main and emergency lighting was lost in the conning tower and adjacent compartments. Shock damage to control panel contacts put bow plane tilting motor out of commission for several hours but planes were shifted to hand control. Both periscope head windows were shattered, No. 1 periscope upper prism fractured, and the tubes of both periscopes flooded. Power to trim pump, drain pump, hydraulic pump and other auxiliaries was temporarily lost. Mercury was displaced from master gyrocompass, putting it out of commission and the magnetic compass binnacle tube flooded, preventing its use for steering. Serious leakage occurred in conning tower around binnacle tube flange and after bulkhead door. Bridge instruments were smashed and flooded. Numerous external electrical cables were flooded. Low pressure blow valve to MBT No. 1 opened, allowing low pressure manifold to flood. SJ radar bearing indicator shaft was bent. Numerous gauges, meters and instruments were broken or deranged and much other minor damage occurred. Immediately after the bombing, and in spite of the damage, RUNNER fired two more torpedoes and then went to 200 foot depth to evade enemy surface vessels. The patrol was terminated due to derangement of both periscopes. |
--261--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
KINGFISH (SS234) |
3/23/43 |
Off Formosa |
Depth Charges - 41 |
Depth charged by small Japanese destroyer or minelayer while at 300 foot depth. Severe damage resulted. See Section V for detailed account. Ship terminated patrol. |
HADDOCK (SS231) |
4/3/43 |
Off Palau Islands |
Depth Charges - 24 |
Depth charged by Japanese corvette. Two charges detonated close aboard while passing 250 foot depth and several more close charges were received while at 350 foot depth. As attacks continued, HADDOCK increased depth still further. When 415 foot depth was reached, two local areas of conning tower pressure plating, port and starboard, suddenly bulged inward to a maximum extent of about four inches in way of discontinuity in connection of external stiffeners to conning tower plating. Conning tower was promptly abandoned and boat planed up to 300 foot depth. With exception of misalignment of SJ radar training mechanism, no other damage occurred. Ship terminated patrol. |
GATO (SS212) |
4/1/43 |
Off New Ireland |
Depth Charges - 6 |
Depth charged by Japanese corvette. First charge detonated close aboard port side aft while passing 150 foot depth and caused major portion of damage sustained. Main battery positive and negative bus bars in control cubicle jarred together and arced, causing battery disconnect switches to trip. Main power was consequently disrupted for brief period but was regained in time to check descent at 380 foot depth. Auxiliary power was also lost by tripping of auxiliary power panel switches but was restored immediately. Pressure hull plating was dished inward between frs. 119-130, both port and starboard, in way of after torpedo room and after trim tank. Maximum indentation was 2 inches. Grease line nipple in after trim tank failed, allowing that tank to completely flood from sea. After WRT tank then flooded from after trim through leaking valves. All four after torpedo tubes were distorted sufficiently to require their renewal. Torpedoes within the after tubes were damaged as well as guide studs and tube operating gear. Steering ram cylinders were thrown out of alignment. MBT No. 1 riser leaked slightly at flanges. Miscellaneous other damage of minor nature occurred, principally in after portion of ship. Ship terminated patrol due to inability to maintain satisfactory depth control because of leakage into after trim tank. |
--262--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PIKE (SS173) |
4/23/43 |
Off Central Carolines |
Depth Charges - 8 |
Depth charged by Japanese escort while at 250 foot depth. Insulators for generator and battery bus bars in control cubicle shattered in numerous places. Leak occurred at cone joint connecting high pressure air line to 200 lb. air manifold. Silver soldered joint ruptured on No. 4 main engine circulating water line. Overload relay for main motor cooling system pump tripped, putting pump temporarily out of commission and standby circulating water pump for main motor cooling system flooded from motor room bilges when ship took large up angle. Blower for No. 2 main motor and stern plane motor jarred out of alignment. Numerous gauges, instruments, and light bulbs were broken or deranged and other minor damage occurred. Patrol was terminated due to control cubicle casualty. |
POLLACK (SS180) |
5/20/43 |
Off Southern Marshalls |
Depth Charges - 21 |
Depth charged by Japanese CHIDORI Class torpedo boat while at deep submergence (exact depth not reported). Main battery contactors in control cubicle tripped open, causing temporary loss of all propulsion power. Bow planes lost power and stalled on hard dive position. Auxiliary power contacts for several pumps in engine room closed, starting pumps. Hydraulic line to MBT No. 7 flood valve carried away, allowing considerable oil to escape from hydraulic system. Low pressure blow line to MBT No. 7 was ruptured. After bodies flooded on three torpedoes loaded in tubes. Firing circuit for No. 2 torpedo tube was shorted by loose stud which fell across terminal connections in conning tower. Miscellaneous other minor damage occurred. Ship remained on patrol. |
--263--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
TINOSA (SS283) |
6/10/43 |
Off Kyushu 31°-14'N. |
Depth Charges - 12 |
Depth charged by Japanese PC while heading deep Immediately after firing torpedoes. One charge detonated close aboard while passing 200 foot depth. Bridge instruments were smashed and flooded. Mercury was displaced from both gyrocompasses. Trim pump motor controller cover jarred loose, grounding starter, and trim pump snifter line sheared off, placing pump temporarily out of commission. Radio antenna trunk flooded. Numerous gauges and instruments were deranged, light bulbs broke, and miscellaneous other minor damage occurred. Ship remained on patrol. |
SARGO (SS188) |
6/14/43 |
Off Palau Islands |
Depth Charges - 4 |
Depth charged by Japanese SC while submerged (depth not reported). No. 1 deck torpedo tube was put out of commission for remainder of patrol due to rupture of forward roller drain. No. 1 low pressure blower reduction gear crankcase fractured, placing blower out of commission. External flanges on forward torpedo tube impulse air system developed leaks to sea and Nos. 2, 3, and 5 high pressure air bank piping also developed leaks. MBT No. 1 vent valve gasket was dislodged. Key in bow plane tilting linkage in forward torpedo room was jarred out but was immediately replaced. Several gauges were deranged and numerous valves backed off. Ship remained on patrol. |
GUARDFISH (SS217) |
6/19/43 |
North of Bismarck Archipelago |
Depth Charges - 7 |
Depth charged by Japanese SC while at 325 feet. First charges forced boat down to 360 feet. Both JK-QC and QB sound gear were disabled due to power fuses becoming dislodged. MBT No. 1 vent riser leaked at two flanges. External high pressure air leaks occurred at banks Nos. 4 and 5, requiring after halves to be secured. TBT's on bridge flooded, Stop bolts and gyro spindles were bent on several torpedo tubes. Pitometer log was deranged. Miscellaneous other minor damage occurred. Ship remained on patrol. |
--264--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
JACK (SS259) |
6/26/43 |
Off Southern Honshu |
Bomb - 1 |
Bombed by unidentified Japanese aircraft while at periscope depth preparing to fire torpedoes. Bomb detonated close aboard port quarter. Stern broached. Bow and stern plane power control was lost. Stern planes were quickly shifted to hand operation but control was not regained until several minutes later on bow planes due to obstructing chain guard in forward torpedo room. Boat took 25° down angle and went deep. Descent was checked at 380 feet by blowing bow buoyancy tank and backing with full power. SJ radar was put out of commission probably due to dipole trouble in mast. No. 2 periscope was deranged. External air leak developed at high pressure air bank in MBT No. 2D. Many torpedo tube gyro spindles, stop bolts and torpedo guide studs were damaged. Main engine air induction piping developed leakage through bolted inspection plates. Gaskets were blown out of safety tank and MBT No. 2A master vent valves. Miscellaneous other minor derangements occurred throughout boat. Ship remained on patrol. |
GURNARD (SS254) |
7/6/43 |
Off Palau Islands |
Bombs - 2 |
Received two bombs from unidentified Japanese aircraft while passing 90 foot depth shortly after taking periscope observation. Power on bow planes was lost temporarily due to tripping of contacts in rigging interlock switch. Ship took large up angle and started to lose depth. Rise was checked at 55 feet by backing with full power, sending 50 men to forward torpedo room, and flooding negative and variable tanks. Ship then dropped rapidly and passed 450 feet before depth control was regained. Meanwhile 4 depth charges were dropped by Japanese destroyer but these were not close. Stern plane operation became very noisy. Conning tower door frame was cracked (2 in. long) at recess in door frame for lower dog. Engine air induction piping and negative tank developed steady leakage. Ship remained on patrol. |
--265--
NAME |
DATE |
SOURCE |
PLACE |
REMARKS |
SEAL (SS183) |
7/8/43 |
Off Northern Honshu |
Bomb & Depth Charges - 72 |
Depth charged by ASASHIO Class Japanese destroyer and later bombed by Japanese float plane which followed oil trail caused by first attack. 72 bombs and depth charges were dropped on SEAL over 10 hour period. Except for external fuel oil leakage, the source of which could not be determined, all other damage was of minor nature. Small internal leak developed in fuel oil transfer line in pump room and No. 2 auxiliary tank leaked from sea, causing the boat to become heavy overall. Patrol was terminated due to serious oil leakage. |
TUNA (SS203) |
7/29/43 |
Off Woodlark Is. |
Bombs - 4 |
Detected while running surfaced at night by RAAF CATALINA. Submerged immediately and received four bombs close aboard while passing from 70 to 110 feet. Second bomb detonation caused loss of both main and auxiliary power. Bow and stern planes were shifted to hand power. Propulsion power was restored between 200 and 250 foot depth and by backing emergency and blowing tanks descent was checked at 365 foot depth. Hydraulic power was lost and tank vents were not opened in time to prevent broaching so TUNA surfaced. Ship took 18° list. Conning tower door leaked badly. Both batteries showed full voltage ground. Both periscopes were disabled. No. 2 low pressure blower was deranged. All main vent valve gaskets leaked. Miscellaneous other damage of minor nature occurred. Patrol was terminated. |
SAURY (SS189) |
7/31/43 |
Philippine Sea |
Ramming |
Run down by Japanese destroyer while at periscope depth. Destroyer passed directly overhead from abaft the port beam. No depth charges were dropped. Nos. 1 and 2 periscopes, 3D and SJ radar masts and supporting shear structures were bent about 30° to starboard. Holding down bolts on shears parted at "A" frame level and foundations of shears were bent. No. 1 periscope window fractured and tube flooded. Slight leakage into conning tower occurred around hull flange of No. 2 periscope stuffing box at depths below 200 feet. Patrol was terminated. |
TUNNY (SS282) |
8/26/43 (4th) |
Off Palau Is. |
Depth Charges - 8 |
Depth charged by Japanese PC while at 300 foot depth. Severe damage resulted. See Section VI for detailed account. Ship terminated patrol. |
--266--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
SEAHORSE (SS304) |
9/6/43 |
Off Palau Islands |
Depth Charges - 35 |
Depth charged by Japanese PC and/or gunboat shortly after attacking convoy. Ship's supply ventilation and engine air induction piping developed leakage at rate of about 2000 lbs. per hour. No. 4 torpedo tube flooded through muzzle door. Vent riser flanges for MBT Nos. 1 and 7 leaked into both torpedo rooms. Packing around bow plane tilting shaft loosened, causing serious leakage. Bridge gyro repeater flooded and water traveled through cable to gyro repeater panel inside ship, salting one switch and grounding several connections. Ship remained on patrol. |
SCAMP (SS277) |
9/18/43 |
North of New Guinea |
Depth Charges - 15 |
Depth charged by Japanese destroyer escort while at 320 foot depth. Forward torpedo room took in 7000 lbs. water through ruptured pitometer log gland before gate valve could be secured. Small electrical fire started in trim pump motor controller, which was dislodged from its foundation, and small fire also started in pump room control panel. Bow plane rigging motor shifted on its foundation, preventing power rigging of planes. Engine air induction piping commenced to leak slowly and after engine room induction hull flapper valve was distorted so that it would not properly seat. JK-QC sound gear jammed. Bridge TBT flooded. Many grounds developed in electrical circuits. Stern plane noise level greatly increased. Numerous gauges and meters were deranged or broken and much other minor damage occurred. Ship remained on patrol. |
SKATE (SS305) |
10/6/43 |
Off Wake Island |
Strafing (.25 cal.) |
Strafed by Japanese ZEKE while surfaced. Plane came in low from the starboard beam. STS ballistic plating (30 lb.) shielding conning tower was penetrated by one .25 cal. projectile which struck nearly normal to the surface. A second .25 cal. projectile, which also struck almost normal to the plating surface, was stopped just short of passing completely through. Fragment of another projectile severed bourdon tubing of bathythermograph, putting it out of commission. No other damage occurred. Ship remained on patrol. |
--267--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PUFFER (SS268) |
10/9/43 |
Makassar Strait |
Depth Charges - 46 |
Depth charged by CHIDORI Class torpedo boat while at deep submergence. Second escort later joined attack. Depth charging extended over 14 hour period and PUFFER was then tracked for an additional 12 hours by the enemy vessel. Engine air induction and ship's supply ventilation outboard valve gaskets were blown out, allowing both systems to completely flood. All deck hatches, conning tower door and forward escape trunk door fluttered on each close depth charge and leaked continuously thereafter. Boat became heavy overall, principally due to flooding mentioned above. Depth control was maintained by running at slow speed with a 12° up angle and by gradually blowing negative, safety, auxiliary and after trim tanks. Boat reached 500 foot maximum depth. All bilges flooded. Trim pump (reciprocating type) was too noisy to permit its use. Rudder and stern planes developed high noise level, apparently due to misalignment. Leakage developed at external piping silver soldered joints of No. 4 air bank. Radio antenna trunk flooded. Plug for previously removed sea pressure gauge line in maneuvering room water closet sea valve backed out, allowing considerable water to enter after torpedo room. Flanged joint of trim line ruptured in after torpedo room. Both JK-QC and QB sound training motors were grounded by flooding and both sound head shafts were slightly misaligned. No. 1 air conditioning circulating water pump motor grounded due to flooding. Brushes were jarred loose on Nos. 1 and 2 lighting motor generators. Gyro spindles were bent on torpedo tubes Nos. 5, 6, 9 and 10. Air pressure inside boat increased to six pounds above atmospheric, air temperature reached 125° F. and CO2 content increased considerably, causing much discomfort to all hands. Numerous light bulbs, gauges and instruments were broken or deranged and much other minor damage occurred. Dive lasted 38 hours. Ship terminated patrol. |
--268--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
ALBACORE (SS218) |
11/10/43 |
Off New Ireland |
Bomb |
Bombed by four-engine U.S. bomber while submerging. Main lighting and auxiliary power were temporarily lost. Stern planes were stalled on 15° dive position. Engine Induction outboard valve went under surface before being closed and induction piping system partially flooded. Ship reached 450 feet before descent could be checked and for next 2-1/2 hours oscillated between 30 feet (broach) and 400 feet, at various angles, the worst of which was a 25 degree up angle at 400 feet. 220 volt ground on forward battery and 90 volt ground on after battery occurred due to acid jarring from battery cells and shorts in emergency lighting circuits. Miscellaneous other minor damage occurred. Ship remained on patrol. |
TRIGGER (SS237) |
11/13/43 |
East China Sea |
Depth Charges - 5 |
Depth charged by Japanese MOMI Class destroyer while at 200 foot depth. No. 2 main motor developed noise and vibration due to a commutator segment becoming dislodged and causing brushes to chatter. Steady thump developed in port reduction gear at depths greater than 150 feet at all speeds. No other damage was reported. Ship remained on patrol. |
THRESHER (SS200) |
11/13/43 |
Off Truk |
Depth Charges - 20 |
Depth charged by two or three Japanese escorts while at about 300 foot depth. Sea water entered main hydraulic system through leak in external replenishing tank or piping located forward of conning tower. Engine air induction piping and radio antenna trunk flooded. Patrol was terminated due to hydraulic system casualty. |
--269--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
NAUTILUS (SS168) |
11/19/43 |
Off Tarawa |
Gunfire - 2 (5-inch) |
NAUTILUS made a quick dive upon being shelled by U.S. destroyer but received one hit and one near-miss before going under. The hit, a 5-inch common projectile (dud), struck superstructure plating abreast after end of conning tower; demolished low pressure blow lines for after and middle groups of main ballast tanks, preventing blowing of those tanks except by closing emergency vents and using high pressure air; tore jagged hole (1' x 2') in auxiliary engine air induction piping, allowing that system to flood and requiring 6° up angle on the boat with full speed to maintain depth control due to the added weight; ricocheted off conning tower plating leaving a deep gouge one foot long; struck a main strength frame, tearing it from the pressure hull; ricocheted off periscope trunk, bending it and loosening a few rivets; and finally came to rest on tank top in superstructure where it was later retrieved. Pressure hull proper was not penetrated. Voice tube valve at hull in conning tower was damaged so that it could not be closed and considerable Inboard flooding resulted, grounding one high pressure air compressor motor, both periscope motors, one low pressure air compressor motor, two lube oil purifier motors, the IMC, IC frequency control, gyro follow-up system and the IC distribution board. The near-miss, also 5-inch, detonated close aboard aft and ruptured a salt water line to the port main motor cooler, causing motor room bilges to flood. Ship remained on patrol until mission of supporting landing was accomplished. |
DRUM (SS228) |
11/22/43 |
North of New Guinea |
Depth Charges - 11 |
Depth charged by two Japanese PC's while at about 300 foot depth. Conning tower after bulkhead plating and door frame cracked in way of door upper hinge. Leakage through crack was minor, however, being only 2 or 3 3 gpm at deep submergence. MBT No. 7 vent riser leaked at flange. Maneuvering room hard patch leaked over control cubicle. Torpedo impulse air system forward leaked slightly. No. 2 periscope optics were deranged. Ship terminated patrol. |
--270--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
TINOSA (SS283) |
11/22/43 |
Off Palau Islands |
Depth Charges - 40 |
Depth charged by Japanese AM and/or PC while at about 300 foot depth. First close detonations caused loss of power on bow and stern planes. Boat took 15 up angle and rose to 250 foot depth, then took 20° down angle and descended to 380 foot depth where ship control was finally regained by shifting to hand operation on planes. I.C. motor generator was disabled, putting rudder angle indicator, diving plane Indicator and gyro compass out of commission. Valve closed on steering hydraulic piping system, rendering it temporarily impossible to move rudder to left. Other minor damage occurred. Ship remained on patrol. |
BOWFIN (SS287) |
11/28/43 |
Off Central Philippines |
Gunfire - 1 |
While conducting surface torpedo attack on Japanese convoy, an enemy AP or AK opened fire on BOWFIN with a 3-inch or 4.7-inch gun and secured one hit which detonated in superstructure at frame 70 near starboard engine air Induction piping. Fragments punctured induction and hull ventilation piping, low pressure blow lines to middle and after groups of ballast tanks and fuel oil compensating line to stand pipe. Tank top of MBT No. 4a was dished in. Miscellaneous other minor damage occurred to superstructure. Pressure hull proper was not penetrated. Ship's force patched holes sufficiently to permit submerged operations. Patrol was terminated. |
SAILFISH (SS192) |
12/7/43 |
Off Kyushu |
Bombs - 2 |
Dived upon hearing strafing approach of Japanese ZEKE aircraft and received two bombs while passing about 40 foot depth. First bomb caused no damage. Second bomb detonated close aboard on starboard side abreast maneuvering room. Main propulsion power was lost temporarily due to the jarring open of main motor field excitation circuits In control cubicle and tripping of starboard main motor reverser contactor which arced and welded itself In open position. No. 1 main motor flashed to ground, its brush rigging insulators cracked and a bare spot was burned on a pole face winding. Repairs to this motor were made but It again flashed over on 9 December and was cut out of service for remainder of patrol. Reduction gear noise level increased markedly as result of bombing. Serious leak developed at hull flange of main motor cooler circulating water discharge line. Other minor damage occurred. Ship remained on patrol. |
--271--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
POGY (SS266) |
12/13/43 |
Off Palau |
Depth Charges - 3 |
Depth charged by Japanese PC while heading for deep submergence from periscope depth. Pattern of three close charges detonated close aboard while passing 150 feet. All torpedo tube gyro spindles and depth setting spindles were bent. Leakage into MB? No. 4a (source not reported) caused that tank to remain flooded on surfacing and MBT 4B had to be kept flooded during remainder of patrol to compensate for list. Six engine thermometers and after battery air flow meter were broken. No other damage was reported. Ship terminated patrol due to torpedo tube damage, spindle spares being available for only two tubes. |
SWORDFISH (SS195) |
1/13/44 |
Off Central Honshu |
Depth Charges - 24 |
Depth charged by three Japanese escorts while at 320 foot depth. No. 1 periscope lost nitrogen pressure and lenses of No. 2 periscope were jarred out of alignment. JP and JK-QC sound heads were disabled. Cast Iron plug was blown out of main motor cooling piping. Conning tower hatch opened momentarily, allowing water to flood conning tower bilges. Clamping shoe on port main motor parallel contactor in control cubicle jarred loose and a securing wing nut on emergency power cable in pump room backed off but these derangements were not discovered until the next dive. At that time the cable in the pumproom fell against Its cabinet due to the down angle on the boat, starting a fire, and the control cubicle clamping shoe grounded, causing its contactor to weld itself closed. Both main and auxiliary power were lost. Attempts to put the main motors on battery power caused circuit breakers to operate each time due to short circuit in cubicle. Ship finally submerged with power on the starboard shaft only after pulling port main motor disconnect switches. Temporary repairs were made and the ship remained on patrol. |
--272--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
GATO (SS212) |
12/20/43 |
North of Bismarck Archipelago |
Depth Charges - 19 |
Depth charged by two Japanese SC's while at 370 foot depth. One depth charge did not detonate and landed on deck where it was recovered upon surfacing. Bulkhead at frame 77 was slightly distorted so that W.T. door would not completely seat. Outer hull plating aft was slightly dished between frames. Engine air induction and ship's supply ventilation piping flooded. Riser to MBT No. 1 leaked at hull flange. Many gauges, instruments and light bulbs were broken or deranged and much other minor damage occurred. Ship remained on patrol. |
TAMBOR (SS198) |
2/3/44 |
East China Sea, |
Depth Charges - 32 |
Depth charged by Japanese destroyer shortly after submerging. First six charges forced ship to bottom in 268 feet of water where she received 26 more charges. Bed plates of both high pressure air compressors fractured around complete periphery. Both low pressure air compressors were dislodged from their foundations. Conning tower after bulkhead door frame cracked. Forward and after fuel oil filling line hull valves jarred partially open and plugs on topside standpipes backed off, allowing oil to leak to sea and thereby disclosing ship's presence to enemy destroyer. Oil also leaked from NFO No. 5 and FBT No. 5 (source not reported). Operating mechanism for ship's supply ventilation hull valve was damaged and valve could not be closed again after it was opened on surfacing. Low power field of No. 1 periscope was deranged. All gyro spindles were bent and torpedo guide studs and tube stop bolts were damaged. High pressure air leaks developed at No. 1 air bank in forward battery well. Stern plane drive shaft pinion bearing was damaged, causing high noise level. Radio antenna trunk partially flooded. QC sound gear training motor housing broke and motor was torn loose from bulkhead. Temporary repairs were made and ship remained on patrol. |
--273-
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PERMIT (SS178) |
2/13/44 |
Off Western Carolines |
Depth Charges - 33 |
Depth charged by Japanese destroyers while at 290 foot depth. Engine air induction system flooded and considerable water was taken into engine room bilges through inboard drains and inboard hull valves. All four main engines and both auxiliary engines flooded through leaking inboard and outboard exhaust valves. Ship became heavy aft and overall. Depth control was maintained by increasing speed to 90 rpm with occasional spurts to 180 rpm and by putting 15° to 18° up angle on boat. Maximum depth reached was 320 feet. Ship surfaced three hours later with battery almost depleted. Ship remained on petrol. |
TANG (SS306) |
2/23/44 |
Off Marianas Islands |
Detonation |
A Japanese ammunition ship apparently mass detonated following torpedo attack by TANG. Shock of detonation at range of 1400 yards dislodged muzzle door gasket (not T-shaped) from No. 5 torpedo tube while door was open. During later dive, at 400 foot depth the breech door gasket of same tube bulged out under pressure and admitted water to forward torpedo room faster than pumps could handle. Ship remained on patrol. |
ROCK (SS274) |
2/29/44 |
Off Nansei Shoto Islands |
Gunfire - 1 |
While conducting night surface radar attack on a Japanese convoy, ROCK was detected by enemy destroyer and shelled at close range. Five seconds after diving, and with both periscopes down, one 5.5 inch projectile struck port side of No. 2 periscope shear about seven feet below top. Numerous fragment holes were torn in periscope and radar shears, conning tower fairwater and bridge decks. Bearings of both periscopes were misaligned so that neither could be raised or trained. The upper prisms of both periscopes were shattered. The SD radar mast flooded. Searchlight and running light cables were severed and water passed through sheathing to terminal boxes in the conning tower. Conning tower and pressure hull were not penetrated at any place by fragments. Miscellaneous other minor damage occurred. Ship terminated patrol. |
--274--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
TUNNY (SS282) |
3/30/44 |
Off Palau Islands |
Bomb - 1 |
Bombed by U.S. TBF while surfaced on lifeguard duty. War Patrol Report states bomb was 2000 lb. and struck sea 10 yards to starboard of forward engine room, detonating abreast maneuvering room. YORKTOWN (CV10) Air Combat Action Report states bomb was 2000 lb. and struck water about 50 yards off starboard quarter. Boat made quick dive to 150 feet. Shock caused movement of bus bars in control cubicle (shock mounted) and generator bus bar and bus tie closed contactor were burned by arcing to control cell frame. Main propulsion power was taken from battery until electrical repairs were completed next day. Main motor commutators were slightly burned by brushes lifting clear and drawing arc. Numerous hydraulic system leaks occurred from control room to after torpedo room. SJ radar training gear was misaligned and SJ lobe switching motor was disabled. All after torpedo tube muzzle door gaskets were cut and all four remaining torpedoes were damaged. Both torpedo tube blow and vent manifolds were torn loose from their supports. Excessive leakage developed around starboard stern tube gland. Miscellaneous other minor damage occurred. Patrol was terminated due to damage to torpedoes. |
RAY (SS271) |
3/18/44 |
Off North Borneo |
Depth Charges - 44 |
Depth charged by two Japanese escorts while at 365 foot depth. Stern planes temporarily jammed twice in hand power and were noisy In operation. Bridge pelorus glass was shattered. Four-inch deck gun telescope flooded. Auxiliary engine outboard exhaust valve jammed closed and could not be opened In either hydraulic or hand power. Steering system hydraulic by-pass valve nipple broke. Numerous gauges, instruments, and light bulbs were broken or deranged and other minor damage occurred. Ship remained on patrol. |
SCAMP (SS277) |
4/7/44 |
Off Mindanao, P. I. |
Bomb - 1 |
Received one bomb from Japanese float plane while passing 40 foot depth. Severe damage resulted. See Section IX for detailed account. Ship terminated patrol. |
--275--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
TRIGGER (SS237) |
4/8/44 |
Off Marianas Islands |
Depth Charges - 33 |
Depth charged by several Japanese escorts while at about 300 foot depth. One pattern of six close charges caused majority of damage sustained. Ship's supply ventilation piping topside flooded. Forward torpedo room flooded to level of floor plates through jammed torpedo tube poppet valve. Both sound gear training motors were grounded by flooding. QB sound head was rendered insensitive. Engine room, motor room and pump room bilges flooded to level of lower flats. SD antenna mast head was fractured and mast partially flooded. Both SD and SJ radar transmitters were disabled due to broken tubes. High pressure air leak occurred at No. 2 air bank in MBT No. 2. Electrical fire started in bow plane tilting motor connection box and magnetic brake coils. No. 2 I.C. motor generator was deranged. Steering and stern plane motors jarred out of alignment, running hot and with high noise level. Trim pump lube oil cooler ruptured, allowing sea water to enter pump oil casing. Bridge TBT's flooded. Radio antenna trunk flooded. No. 7 stern torpedo tube shutter jumped track, apparently due to depth charging. Miscellaneous other minor damage occurred. TRIGGER was boxed in by enemy escorts for 17 more hours although running silent at 300 feet. Air temperature inside boat during this period reached 130°. Ship remained on patrol. |
PAMPANITO (SS383) |
4/7/44 |
Off Marianas Islands |
Depth Charges - 7 |
Depth charged by Japanese escort while at deep submergence (depth not reported) Engine air Induction piping topside flooded slowly through leaks at flanged joints. Several rivets on Nos. 1 and 3 main motor brush rigging sheared. Mercury was splashed from auxiliary gyrocompass. Nos. 1 and 2 periscope objective lenses were chipped. Battery cells of torpedo in tube No. 8 cracked; exploder on torpedo in tube No. 2 flooded; afterbodies of torpedoes in tubes Nos. 5 and 6 flooded; muzzle door gaskets on tubes 5, 9 and 10 were cut. Both bridge pressure-proof speakers were damaged and cables to pressure hull from speakers flooded. Many light bulbs were broken. Numerous valves opened, including safety tank inboard vent and outboard vent to No. 1 sanitary tank, allowing the latter tank to flood. Other minor damage occurred. Ship remained on patrol. |
--276--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
ROBALO (SS273) |
4/24/44 |
Off French Indo-China |
Bomb - 1 |
Submerged upon sighting Japanese BETTY and received one bomb close aboard port side forward while passing 55 foot depth. Engine air induction system was inadvertently flooded on dive by personnel error which prevented induction trunk valve from closing in power. This valve was closed by hand before the bomb detonated but depth control was lost temporarily due to boat becoming heavy overall. Descent was checked at 350 feet by putting air bubble in bow buoyancy and safety tanks. SJ radar was disabled both electrically and mechanically. No. 1 periscope upper window shattered and periscope flooded. No. 2 periscope low power field was rendered inoperative. Upper conning tower hatch leaked above 45 foot depth and lower conning tower hatch was distorted so that it would not seat properly. MBT Nos. 1 and 4B main vent valve gaskets were partially blown out and MBT No. 1 riser leaked badly at flange in forward torpedo room. JP sound head was disabled. Radio antenna trunk flooded. Steering system change valve in control room was damaged and caused considerable loss of hydraulic oil. Bridge instruments were smashed and flooded. High pressure air leak occurred at bank in MBT No. 2. Torpedo impulse air system forward also developed external leakage. About 50 light bulbs were broken, including all emergency lights forward of after battery room. Pitometer log sword arm was ruptured and log flooded. Numerous gauges, meters, and instruments were deranged or broken and much other minor damage occurred. Ship remained on patrol. |
--277--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
CREVALLE (53291) |
5/14/44 |
Off Northern Celebes |
Depth Charges - 16 |
Depth charged by CHIDORI Class Japanese torpedo boat. First pattern of eight charges detonated close aboard while at 190 foot depth and second pattern of eight detonated shortly afterward while at 400 foot depth. Pressure hull plating was slightly dished inward at frame 21, starboard. Starboard vent riser from MBT No. 1 leaked at flange. Both dogs on forward escape trunk lower hatch sheared off. Locking rings on torpedo tube breech doors rotated towards open position. Flange in officer's head flushing line leaked seriously, causing torpedo room bilges to flood. Sound training motors were thrown out of alignment and flooded. Short circuit in emergency lighting system caused full voltage ground on forward battery. Hydraulic piping leaks forward caused loss of pressure in system. Both periscopes were damaged and SD and SJ radars were disabled. Leakage occurred around steering wheel shaft in conning tower. All sanitary tanks flooded when discharge valves opened. Numerous valves opened, small leaks developed in various piping systems, gauges were deranged, and other minor damage occurred throughout boat. Ship was returning to base when attacked. |
PICUDA (SS382) |
5/20/44 |
Luzon Strait |
Depth Charges - 14 |
Depth charged by Japanese escort. Received three close charges while at 70 foot depth. Second charge detonated close abreast conning tower and heeled ship to port. Third charge detonated under stern, forcing stern up and giving ship large down angle. This third detonation also tripped starboard main motor contactor but it was immediately closed and power restored. PICUDA went deep, receiving 4 more close charges at 150 foot depth, 4 at 250 foot depth and 3 at 450 foot depth. Several broken brushes were later found in the Nos. 3 and 4 main motors. Engine air induction line flooded. Contacts in No. 2 I.C. motor generator control panel jarred loose. Trim line sea. suction piping seam split at trim manifold. Brazed joint on No. 2 sanitary flushing line cracked. Lube oil line in after engine room carried away. After torpedo tube gyro spindles were bent and tube No. 9 flooded. Magazine flooding line manifold casting was cracked. Numerous valves jarred open on hydraulic system, fuel oil filling and transfer system and lube oil filling line hull connections. Several pressure gauges and thermometers broke. Heavy rumble developed on port shaft at 50 rpm and higher. Ship remained on patrol. |
--278--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
BLUEGILL (SS242) |
5/22/44 |
Off Halmahera |
Bombs - 2 |
Received two bombs close aboard from Japanese BETTY, the first at 40 foot depth just after submerging and the second while passing 200 foot depth. Bow planes lost power while in hard dive position. Depth control was lost and boat took 25° to 30 down angle. Regained depth control at 250 feet by backing emergency and blowing bow buoyancy tank. Bow plane operation was restored by shifting to hand control. SJ radar was disabled and SJ radar mast was thrown out of alignment. No. 1 main motor became noisy due to chattering of displaced brush rigging. Forward battery soft patch leaked. Miscellaneous other minor damage occurred. Ship remained on patrol. |
FLYING FISH (SS229) |
5/24/44 |
Philippine Sea |
Own Torpedo |
While retiring after delivering an attack, a probable premature detonation of one of FLYING FISH's own torpedoes (Mk.18) occurred close aboard aft. Ship was surfaced and proceeding at standard speed on all four main engines. Nos. 1, 2 and 3 main generator contactors in control cubicle tripped under shock and Nos. 1, 2 and 3 main Diesels surged as result of loss of load. Voltmeter fuses for Nos. 1, 2, 3 and 4 main motors and main generators burned out. Severe arcing occurred. No. 4 main generator remained in operation. No. 3 main generator was put on line by estimating voltage and paralleling it with No. 4 generator. Propulsion was then shifted to main batteries. Shock also tripped bow plane rigging motor panel contactors, causing pilot circuit fuses to blow. Planes were rigged out by hand on subsequent dive. Ship remained on patrol. |
PERMIT (SS178) |
5/28/44 |
Off Truk |
Bomb - 1 |
Detected by U.S. VENTURA bomber while running surfaced. Submerged immediately and received one bomb close aboard while passing 15 foot depth. Drain line to compensating system in forward torpedo room carried away, spraying sound gear, pitometer log and other equipment with oil and salt water. Power was lost on bow planes. After battery developed full voltage ground. High pressure air manifold developed leaks. Various bridge instruments flooded out. Numerous gauges and instruments were broken or deranged. Ship remained on patrol. |
--279--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
RATON (SS270) |
6/6/44 |
Off French Indo-China |
Depth Charges - 57 |
Depth charged by several Japanese escorts. First five charges detonated close aboard while running at periscope depth. Vent riser on MBT No. 1 developed leak at flange. QB sound training gear jarred out of alignment and became noisy. JP receiver crystal earphones were deranged and power fuse blew. Pump drive on pitometer log jarred out of alignment. IMC bridge microphone coupling boxes and cables flooded. Four-inch deck gun flooded. Numerous light bulbs were broken and gauges were put out of calibration. Gyro pots and after bodies flooded on three remaining torpedoes loaded in tubes. No other damage occurred. Ship remained on patrol. |
WHALE (SS239) |
6/8/44 |
North of Bonin Islands |
Depth Charges - 29 |
Depth charged by three or four Japanese escorts while at about 350 foot depth. Both propulsion shafts developed vibrations at 70-80 rpm after depth charging and noise level increased, indicating shaft misalignment. Four holding down bolts sheared on reduction gear casings. No. 3 main motor developed squeal at 50 to 70 rpm. No. 2 periscope stuffing gland leaked heavily. Compensating line ruptured in superstructure, causing loss in pressure on fuel oil tank system when surfaced. Vision of both periscopes was impaired by dirt being jarred loose and settling on lenses. SJ and SD radars were disabled. High pressure air line at No. 4 air bank developed small leak. Miscellaneous other minor damage occurred. Ship remained on patrol. |
APOGON (SS308) |
7/12/44 |
Luzon Strait |
Ramming |
While conducting night periscope attack on Japanese convoy, APOGON was rammed from starboard by an enemy AK which passed directly overhead. Depth at time of collision was about 70 feet to keel. Boat was heeled 15° to port. Top of shears, both periscopes and SD and SJ radar masts were bent about 45° to port. No. 1 periscope was sheared off about 8 feet from its head. Water entered conning tower at rate of about 30 gpm, most of it through leaking SJ mast stuffing box. Several depth charges were dropped as APOGON went deep but did no damage. Boat was then caught at 430 foot depth by putting air bubble In safety tank and using trim and drain pump on bilges. Patrol was terminated. |
--280--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
SAND LANCE (SS381) |
8/7/44 |
Off Northern Celebes |
Bombs - 2 |
Received two bombs from Japanese DAVE float plane while passing 70 feet on way up to periscope depth. Bombs detonated close under stern, causing ship to broach. SAND LANCE then went to 430 foot depth to evade surface ship depth charging which followed. Port reduction gear was damaged and developed such a loud knocking noise that port shaft was secured. Starboard propulsion plant control cubicle controllers were jammed by a broken washer, limiting maximum speed on that shaft to two-thirds. At 430 feet it was discovered that Mk. 18 torpedo in No. 8 tube was running hot so ship was planed up to 100 foot depth to fire torpedo. Warhead detonated prematurely about twenty seconds after torpedo left tube. Other damage was minor. Ship terminated patrol as result of reduction gear damage. Return trip was made using starboard shaft only. |
TUNNY (SS282) |
9/1/44 |
Luzon Strait |
Bombs - 2 |
Dived to escape Japanese KATE aircraft. While passing 110 feet, two depth bombs detonated close aboard aft on port side. Second bomb forced boat from 4° down angle to 8° up angle. Both bombs probably were 60 Kg size, set for detonation at 25 meters depth. Pressure hull plating was dished In between several frames on port side in way of after torpedo room and after end of maneuvering room. Maximum indentation of plating was about 1 inch. Entire propulsion plant was undamaged. Serious leakage occurred at two flanges of port vent riser for MBT No. 7 in after torpedo room, distorted by inward movement of pressure hull aft. This leakage was determining factor in decision to terminate patrol. Gyro setting spindles were bent on all torpedo tubes except No. 1. Pull voltage ground developed due to short circuits in emergency lighting system. Numerous valves jarred open. Rudder was canted to starboard about 3° at bottom. Small leak occurred at union on high pressure air line to separator in after torpedo room. Miscellaneous other minor damage occurred. Ship terminated patrol and returned to base with no difficulty. |
--281--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
ICEFISH (SS367) |
10/26/44 |
Luzon Strait |
Depth Charges - 16 |
Depth charged by Japanese escorts while at 420 foot depth. Severe hull flexural vibrations occurred. 225-pound air supply valve to hydraulic oil vent and replenishing tank jarred open and valve wheel was knocked off. Resulting air pressure forced air volume tank safety valve open, blew down vent and replenishing tank and opened 45 lb. relief valves with consequent loss of most of oil in hydraulic system. Hydraulic system throughout boat developed many piping leaks and line to bow buoyancy vent valve completely carried away. Steering and bow and stern planes went out of commission until oil could be put back in telemotors and then could only be operated In hand control since main hydraulic plant was air bound. Even in hand operation, air in piping to bow and stern planes and steering caused loud knocking noises which disclosed ship's location to enemy escorts. Valves jarred open throughout ship, causing full sea pressure on salt water systems. Numerous air, fuel oil and salt water leaks developed. No. 1 sanitary tank flooded and blew through water closet and inboard vent into forward torpedo room. Fuel oil leaked to depth of 2 inches on deck in after battery room through opened fuel tank inboard vent. Serious periscope packing gland leaks caused water to flood into conning tower bilges and thence into control room and periscope wells. Vent riser piping topside for FBT Nos. 3B and 4B was dished In to depth of 4 inches over 4 to 5 foot length. Low power field In No. 1 periscope was deranged. All bow torpedo tube gyro spindles were bent and could not be withdrawn. Torpedo in No. 4 tube had "hot" run, hydrogen explosion or both. Guide studs on all torpedoes were sheared back about 1 inch. All bow tube inner door locking rings rotated open 1/3 of circumference. Numerous small electrical fires and grounds occurred. Most light bulbs throughout ship were broken. Coil In tube nest of No. 2 generator cooler ruptured. JP and QB sound gear were disabled. Numerous other items of minor damage occurred. Main propulsion and vital auxiliaries were undamaged except for hydraulically operated equipment. Ship terminated patrol. |
SALMON (SS182) |
10/30/44 |
Off Kyushu |
Depth Charges - 30 |
Depth charged by two or more Japanese escorts while at 310 foot depth. Severe damage resulted. See Section VII for detailed account. Ship terminated patrol. |
--282--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
GUITARRO |
10/31/44 |
Off Central Luzon |
Detonation of Ammunition Ship |
A few seconds after heading for deep submergence from periscope depth, two of GUITARRO's torpedoes scored hits on a, Japanese ammunition ship of about 7500 gross tonnage. The resulting mass detonation, 1900 yards distant, forced GUITARRO down rapidly 50 feet in depth. Blue flame is reported to have appeared around both periscope stuffing boxes and after engine room hatch. Inboard vents on NFO No. 1 and FBT No. 3 jarred open under shock and showered forward torpedo room and crew's mess with fuel oil. Pitometer log sword connection was blown off, spraying sound training motor generator and JP-1 sound gear with sea water. Brushes were dislodged from steering motor. Several valve wheels were knocked off and numerous light bulbs were broken. Knock developed in port reduction gear. Ship remained on patrol. |
SAILFISH (SS192) |
11/4/44 |
Luzon Strait |
Bombs - 10 |
Received about ten bombs from unidentified Japanese aircraft while at periscope depth during attack on destroyer "killer" group. No bombs landed very close but one detonation caused No. 7 torpedo tube inboard vent valve to jam open. SAILFISH then headed for deep submergence. Large volume of water entered after torpedo room through this vent before it could be secured and flooded forward end of compartment to depth of 6 inches above deck due to 5° dive angle on boat. Torpedo charging panel grounded from water spray and small electrical fire started. Fire was immediately extinguished by de-energizing the panel but boat then took 25° up angle due to added weight aft and started for surface. Depth control was regained at 170 feet by backing with both shafts and sending men forward. Ship remained on patrol. |
GUITARRO (SS363) |
11/6/44 |
Off Central Luzon |
Depth Charges - 6 |
Depth charged by Japanese escort while at deep submergence (depth not reported). Boat was forced down an additional 50 feet. SD and SJ radars were disabled. Stern planes and steering gear were thrown out of alignment and became noisy. All bridge electrical circuits shorted and 1 1/4 inch pressure proof quartz in bridge gyro repeater was shattered. Radio transmitter was disabled and antennae insulators topside fractured. Both periscope stadimeters jarred out of adjustment. Many emergency light bulbs were broken. Ship remained on patrol. |
--283--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
HALIBUT (SS232) |
11/14/44 |
Luzon Strait |
Bombs - 4 |
Detected by Japanese plane or planes, apparently equipped with MAD, while attacking convoy at periscope depth. Pour heavy explosions, believed to be depth bombs, occurred within next four minutes but little damage resulted. Twenty minutes later, while at 325 foot depth, severe structural damage was received forward and a great amount of other damage occurred elsewhere throughout ship as a result of close pattern of 8 or 10 depth charges dropped by surface escort. Ship was forced down to 420 feet. Pressure hull plating forward of frame 54 was depressed inward between frames, port and starboard, to maximum depth of about 2 inches (damage in way of forward torpedo room was similar to TUNNY, PLATE VI). Top and sides of MBT No. 1 buckled In forward torpedo room. Bulkhead between forward torpedo room and forward battery compartment buckled. Pressure hull dished inward to depth of 2 inches between forward escape trunk and torpedo loading hatch. Pressure hull plating and framing distortion also occurred in local areas as far aft as forward engine room, including conning tower, safety and auxiliary tanks, and after lube oil tanks (fr. 103 - 108). No. 1 h.p. air bank "tee" carried away, allowing bank to bleed down and caused pressure in forward battery compartment to build up to about 50 psi. This pressure was gradually distributed throughout ship, venting into forward torpedo room by cracking bulkhead door and into control room through trim line hose connection. Pinal overall increase in internal air pressure was 10 psi. Forward escape trunk flooded. Eleven forward battery jars cracked, loosing electrolyte. Bases cracked on ice machine and air conditioning compressors. Both gyrocompasses were deranged. Both main propulsion shafts became noisy. JP sound gear was disabled. Minor damage was sustained by JK-QC and QB sound heads. SD radar mast flooded. VHF and APR were disabled. Batteries in four Mk.18-1 torpedoes forward were damaged beyond repair. Sea valves jarred open throughout ship. No damage occurred to main engines, generators, reduction gears, control cubicle, bow and stern planes, trim pump, hydraulic plant, or any other vital systems or auxiliary machinery with exception of high pressure air system casualty described above. Ship surfaced after attack and returned to base with no difficulty. |
--284--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
BLUEGILL (SS242) |
11/17/44 |
Makassar Strait |
Depth Charges - 47 |
Depth charged by two or more CHIDORI Class Japanese torpedo boats. First charges were received while running at 312 foot depth. Later close charges forced boat down to 384 feet. Forward torpedo loading hatch lifted momentarily. No. 1 MBT vent riser leaked heavily at flange to master vent valve. JP sound gear was disabled. Gyro spindles were bent on all forward torpedo tubes. Many hydraulic system leaks occurred forward. No. 3 sanitary tank flooded through overboard discharge. Auxiliary engine outboard exhaust valve jammed in closed position due to bent stem. Stern plane motor was repeatedly energized due to panel contacts closing with each near detonation. Many light bulbs were broken in main and emergency lighting system, numerous valves jarred open throughout boat, gauges and instruments were broken or deranged, minor piping leaks developed, many electrical grounds occurred and miscellaneous other minor damage was sustained. Ship remained on patrol. |
RONQUIL (SS396) |
11/17/44 |
Off Central Honshu |
Gunfire - 1 (40mm) |
While firing directly astern during gun action with Japanese armed trawler, one of RONQUIL's own 40mm shells apparently detonated either prematurely or on contact with lifeline stanchion aft. Detonation occurred over after torpedo room loading hatch and damage was confined between frames 107 and 115. Pressure hull was penetrated by fragments in two places: (a) 1 1/2" hole between frames 107 and 108 forward of torpedo loading hatch, (b) 1/2" hole in torpedo loading hatch. Pressure hull plating and loading hatch were gouged by fragments in numerous areas. Lube oil filling line, low pressure blow line to MBT No. 7 and high salvage air line to after torpedo room were punctured by fragments. Superstructure deck was riddled between frames 107 and 115. Miscellaneous other minor damage occurred. Pressure hull holes were patched sufficiently well to permit shallow dives and held tight during close bombing which followed one hour after patches were installed. Ship terminated patrol. |
--285--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PARGO (SS264) |
11/26/44 |
Off Sarawak |
Depth Charges - 34 |
Depth charged by two Japanese AM's while running at 160 foot depth in 180 feet of water. Auxiliary engine outboard exhaust valve operating gear jammed and could not be opened by power or hand. Circuit breakers tripped on both I. C. motor generators. No. 2 electric still developed small leak in coils, causing salted distillate. SJ radar lobing mechanism was disabled. Numerous gauges, instruments and light bulbs were broken or deranged and other minor damage occurred. Ship remained on patrol. |
PIPEFISH (SS388) |
11/30/44 |
Off Hainan, South China Sea |
Bombs - 3 |
Submerged upon sighting Japanese VAL aircraft and received 3 bombs close aboard shortly thereafter. Power was lost on stern planes due to electrical damage to tilting motor control panel. Controllers for Nos. 1 and 2 hydraulic pump motors tripped. Torpedo in No. 5 tube ran "hot". Three torpedo tube gyro spindles and one depth setting spindle were bent. Guide studs on all loaded torpedoes were partially sheared. Forward escape trunk 225-pound blow valve opened. 225-pound air volume tank in after torpedo room tore loose from its supporting brackets. Leaks developed in main motor circulating water line and at hydraulic steering control valve. Radio antenna insulators fractured. Numerous light bulbs broke. Miscellaneous other minor damage occurred. Ship remained on patrol. |
BERGALL (SS320) |
12/13/44 |
Off French Indo-China |
Gunfire - 1 |
After completing night surface radar attack on two Japanese heavy cruisers, sinking the first and probably damaging the second, BERGALL was fired on by the latter cruiser with 3 salvos of 2 rounds each from 9000 yards range, receiving one 8-inch/50 cal. dud hit. This projectile passed through forward torpedo room loading hatch structure from port to starboard, tearing a large hole in pressure hull. Shell did not detonate. Fragments torn from hull caused additional damage. Starboard vent riser from MBT No. 1 was punctured, allowing that tank to vent and flood; ventilation system flapper valve in after bulkhead of forward torpedo room was damaged; 225-pound service air line forward was punctured; overhead cables in torpedo room were cut, causing failure of many electrical circuits and several Small fires. BERGALL returned to base running entire distance on the surface. Improvised patches were Installed over loading hatch damage and MBT No. 1 riser by ship's force. |
--286--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
REDFISH (SS395) |
12/19/44 |
East China Sea |
Depth Charges - 13 |
Depth charged by Japanese destroyer shortly after attacking and sinking large CV (UNRYU). Received seven very close charges while passing 150 foot depth. Ship then bottomed in 232 feet of water for next 1 1/2 hours, receiving only six more close charges in spite of intense enemy A/S activity. Severe damage was sustained. Pressure hull plating was slightly dished inward between frames in several areas in way of forward torpedo room and forward trim tank. Tank top plating of MBT No. 1 in forward torpedo room was rippled between frames. MBT No. 1 starboard vent riser leaked profusely at flanged joint. No. 1 sanitary tank overboard discharge sea valve leaked heavily at hull flange and through valve itself. Considerable hydraulic oil was lost due to leaks at flanges on lines to pump room accumulator, steering manifold aft and sonar and bow plane tilting piping forward. This loss of oil disabled entire hydraulic system temporarily, stalling rudder in hard left position and bow planes on 20 rise angle. Failure of hydraulic power also prevented raising of JK-QC sound gear so that it was damaged when ship hit bottom. Torpedo in tube No. 8 ran "hot". Controller for trim pump and starter for low pressure blower were damaged. Metal fuse retained in emergency lighting fuse box jarred loose, causing zero ground. JP sonar shaft was bent and JP head flooded. Both gyrocompasses were deranged. At least 12 battery jars forward were cracked, losing electrolyte and causing full voltage ground. 3100 gallons fuel oil shifted from NFO Nos. 1 and 2 to FBT No. 3 due to fuel oil filling and transfer valves jarring open. Numerous gauges, instruments, and light bulbs were deranged or broken, electrical grounds developed in many systems and equipment, and much other minor damage occurred. Ship terminated patrol and returned to base using all main engines and occasionally diving without difficulty. |
BARBERO (SS317) |
12/27/44 |
Lombok Strait |
Bomb - 1 |
Received one bomb close aboard aft from unidentified aircraft while at periscope depth. Port reduction gear developed loud knock and grinding sound and was placed out of commission to prevent further damage. Several brushes jarred out of position on No. 2 main motor. No other damage was sustained. Ship returned to base using starboard shaft only. Port reduction gear was subsequently replaced. |
--287--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
GREENLING (SS213) |
1/25/45 |
Off Nansei Shoto Islands |
Depth Charges - 95 |
Four Japanese destroyers or large PC's dropped 95 depth charges on GREENLING over a 2-1/2 hour period. Several close charges were received while running at 300 foot depth, forcing ship down to 360 foot depth. Pressure hull plating was dished slightly between frames In several areas aft of frame 105. Frames 127 and 138 were buckled in after trim tank. Main engine mufflers Nos. 1 and 2 were damaged. No. 2 high pressure air compressor bed plate in pump room cracked. High pressure air leaks developed at control room manifold and in forward engine room at No. 5 bank "tee". Five torpedoes ran "hot'* in tubes as result of damage to stop bolts and guide studs. Both gyro compasses displaced mercury. Miscellaneous other minor damage occurred, principally in after portion of ship. Patrol was terminated. |
THREADFIN (SS410) |
1/30/45 |
Off Southern Honshu |
Depth Charges |
Depth charged by several Japanese PC's. First close charges were received while running at 300 foot depth and caused serious leak in cross-connection piping between compensating line and motor cooling system in motor room. Salt water spray barely missed energized control cubicle bus bars. Bucket brigade kept water level in bilges below main motors. Boat went to bottom in 450 feet of water for remainder of attack and the ruptured line was blanked. No other damage was sustained. Ship remained on patrol. |
BURRFISH (SS312) |
2/11/45 |
Off Bonin Islands |
Depth Charges - 39 |
Depth charged by Japanese PC and depth bombed by several Japanese planes while operating at various depths up to 450 feet. No. 5 torpedo impulse air piping developed leak outside hull. All torpedoes loaded in tubes sustained guide stud damage. Negative tank developed leak through flood valve. Miscellaneous other minor damage occurred. Ship remained on patrol. |
--288--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PINTADO (SS387) |
2/20/45 |
Gulf of Siam |
Bombs - 2 |
Submerged upon sighting Japanese DINAH aircraft and received two bombs close aboard while passing 130 foot depth. Loud squeal developed at low speeds (below 50 rpm) on port shaft, apparently due to misalignment of port strut bearing. 5 torpedo gyro spindles were bent. Port revolution counter synchro motor was disengaged from its gear train. Stern plane angle indicator system was put out of commission. Several fuses and light bulbs were blown out and a few valves jarred open. No other damage was reported. Ship remained on patrol. |
PETO |
3/5/45 |
Off Hainan, South China Sea |
Bombs - 3 |
Submerged upon night approach of unidentified radar-equipped aircraft and received three bombs while passing 80 foot depth. Hydraulic system was put out of commission temporarily due to derangement of hydraulic accumulator charging mechanism which prevented movement of pilot valve to open automatic by-pass valve. Oil pressure Increased, causing relief valve to open. Deck gun deflection shaft was bent. No other damage was reported. Ship remained on patrol. |
BREAM (SS243) |
3/15/45 |
Off North Borneo |
Depth Charges - 18 |
Depth charged by CHIDORI Class Japanese torpedo boat. First two charges forced ship to bottom in 100 feet of water where 16 more charges were delivered close aboard. Auxiliary engine flooded through leaking Inboard and outboard exhaust valves. Numerous sea valves opened by as much as two full turns. Forward escape trunk flooded through W.T. door and upper hatch. After battery compartment hatch trunk flooded through upper hatch when its dogs loosened. Both gyrocompasses were disabled. Conning tower hatch lifted slightly and admitted small quantity of water. Bow planes could not be rigged In due to electrical interlock derangement. Air leaks developed in forward torpedo impulse air piping outside hull and from No. 1 high pressure air bank in forward battery compartment. Numerous other items of minor damage occurred throughout boat. Patrol was terminated although BREAM was in sufficiently good materiel condition to make an attack while proceeding to base. |
--289--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
DEVILFISH (SS292) |
3/20/45 |
West of Bonin Islands |
Suicide Plane Crash |
While submerging and passing 50 foot depth, a suicide crash was made on DEVILFISH by Japanese ZEKE fighter plane. Parts of plane struck uppermost portion of periscope shears. Nos. 1 and 2 periscopes were damaged both mechanically and optically. Periscope shears proper were forced slightly out of alignment. SJ radar mast was ruptured at top and water entered conning tower in large volume through damaged antenna assembly at lower end of mast. Conning tower bilges filled and water poured down lower hatch to control room. SD, ST, APR and VHF antennae were destroyed. SD, SJ, SPA and sonar equipment in conning tower were grounded out by flooding and spray. Ship terminated patrol. |
BAYA (SS318) |
3/21/45 |
Off French Indo-China |
Depth Charges - 21 |
Depth charged by Japanese SC while at 220 foot depth. First charges forced ship to bottom in 270 feet of water. Main lighting power was lost. Conning tower hatch fluttered. Numerous sea valves backed off from 1 to 5 turns. 5 torpedo gyro spindles were bent. Pronounced knock developed in port reduction gear. Both periscopes and the master and auxiliary gyrocompasses were deranged. Ship remained on patrol. |
POGY (SS266) |
4/19/45 |
Southeast of Honshu |
Strafing and Bomb - 1 |
Submerged upon strafing attack by approaching U.S. B-24 bomber and received one bomb while passing 30 foot depth. Following damage was caused by .30 cal. and .50 cal. projectiles: (a) VHF and APR antennae coaxial feeder pipes were punctured and water entered these pipes, passed through open hull shear valves and sprayed on radio equipment in radio room before shear valves could be closed; (b) radio antenna trunk was punctured and flooded; (c) safety latch operating rod on 5"/25 cal. deck gun was broken in two by projectile; (d) two .50 cal. projectiles penetrated STS plating below cigarette deck and entered 40 lb. STS ready service stowage for 5"/25 cal. ammunition - no damage occurred to six rounds of high capacity ammunition within; (e) after TBT on bridge was grounded by projectile damage to cable; (f) port radio antenna was shot away; (g) numerous projectiles punctured bridge and periscope shears. No damage was caused by bomb detonation. Ship remained on patrol. |
--290--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
BLACKFIN (SS322) |
3/28/45 |
Off Hon Traunam South China Sea |
Depth Charges - 7 |
Depth charged by Japanese destroyer escort while at about 100 foot depth. Seven charges detonated above and to starboard, forcing ship to bottom in 156 feet of water. Bow planes jammed on 8 degrees dive position. Hydraulic power for stern planes was lost when high vent on telemotor line jarred open. Three Mk. 18-1 torpedoes forward and one Mk. 23 torpedo aft, loaded in tubes, had "hot" runs. Gyro spindles and stop bolts on tubes both forward and aft were damaged. Hydrogen burner rubber sockets were dislodged from torpedo tubes Nos. 2 and 5 and, since outer doors were open, water poured into forward torpedo room until wooden depth charge plugs were Inserted. Both sound heads were damaged when boat hit bottom. 225-pound air to forward escape trunk jarred open, causing pressure to build up and forcing trunk W.T. door partially open. After battery compartment access trunk upper hatch opened momentarily and trunk lower hatch was knocked off its seat, allowing small quantity of water to enter ship. Six-inch cracks extending from after lower corner of No. 8 unit crank case doors to idler and drive gear housings by after holding down studs were later discovered on all four main engines (General Motors, 16-278A). These cracks were not caused by depth charging but were due to construction welding stresses combined with normal service stresses. All radio antennae were knocked down. All compasses were disabled. Numerous valves opened throughout ship and minor air leaks developed. Gauges, meters, and light bulbs were broken or deranged. Patrol was terminated. |
CHUB (SS329) |
4/12/45 |
Java Sea |
Bombs - 4 |
Submerged upon sighting Japanese RUFE aircraft and received 4 small bombs while passing 80 foot depth with hard rise on both bow and stern planes (due to proximity of 19 fathom sounding on chart). Detonation caused hydraulic system automatic by-pass valve to lift and remain open long enough to allow oil in replenishing tank to run back to supply tank. This caused loss of power on both bow and stern planes. Ship broached before power was restored. Optics of No. 2 periscope were deranged. Bow buoyancy vent valve was unseated. Battery of torpedo loaded in No. 1 tube jarred loose, causing damage to hydrogen burner assembly. Other minor damage occurred. Ship remained on patrol. |
--291--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
SEAHORSE (SS304) |
4/18/45 |
Tsushima Strait |
Depth Charges - 50 |
Depth charged by two Japanese frigates. First pattern of 8 or 9 charges was received close aboard and forced boat from 300 foot to 400 foot depth. Propulsion was then secured and SEAHORSE settled on bottom in 470 feet of water. About 40 more charges were dropped but were not close. Damage was extensive. Both reduction gears developed pounding noise at all speeds and starboard shaft groaned loudly, apparently due to strut bearing damage. Sea water entered reduction gear lube oil sumps through rupture In lube oil coolers. Inboard exhaust valve for No. 4 main engine could not be closed. Fresh water expansion tanks for Nos. 2 and 4 engines were cracked. Nos. 1 and 2 air conditioning compressors shifted out of alignment and numerous leaks developed in freon piping. Acid was jarred from many after main battery cells, causing full ground. Conning tower bulkhead cracked slightly around weld for steering wheel packing gland, causing small leak. Hard patches in pressure hull of three compartments developed leaks. Leakage around SD radar mast hydraulic cylinder hull flanges flooded storeroom below. Engine induction outboard valve could not be opened in power due to binding of valve on guide rods. Engine air induction piping flooded and sea water entered boat through distorted engine room induction hull valve. Radio antenna trunk flooded and all radio antennae Insulators fractured. Auxiliary tank flooded through sea valve which jarred open. Inboard vent piping for FBT No. 5 riser carried away, allowing fuel oil to enter boat. Hydraulic system oil poured out through ruptured line to SD radar mast. Bridge instruments, both periscopes and all radio and radar gear were permanently damaged or temporarily disabled. All torpedo gyro spindles and torpedo tube stop bolts were bent. Torpedo data computer jarred out of alignment. Training and elevating mechanism on 40 mm gun was inoperable. Training mechanism on 5-inch deck gun was misaligned and 5-inch ammunition hoist breech door was sprung, allowing hoist to flood. Emergency lighting power failed in after half of ship. Gauges, meters and instruments were broken or deranged, cork insulation was jarred loose in large quantity, and much other minor damage occurred. Ship terminated patrol. |
--292--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
PERCH (II) (SS313) |
4/26/45 |
Off North Borneo |
Depth Charges - 30 |
Depth charged by Japanese minelayer while running at 160 foot depth in 180 feet of water. Flushing line from crew's head developed leak in FBT No. 4b and small amount of fuel oil entered after battery compartment through leak at hull flange of this line. No. 2 periscope was disabled In low power and fogged in high power. Brushes in steering motor were jarred out of alignment. Numerous minor leaks started in freon lines, internal salvage air piping, hydraulic lines and high pressure air lines. Mercury was displaced from auxiliary gyrocompass. Tube in SD radar transmitter broke. JK-QC and QB sonar shafts were misaligned. JP-1 sonar was disabled due to blown fuses, broken tube and short in electrical system. Numerous gauges, light bulbs, brackets, meters and fuses were broken or deranged, and other minor damage occurred. Ship remained on patrol. |
COBIA (SS245) |
5/14/45 |
Gulf of Siam |
Depth Charges - 16 |
Depth charged by Japanese minelayer while at 120 foot depth. First charges forced boat to bottom in 148 feet of water. Water closet valves spun to full open on each of several close detonations. Gyro spindles were bent on six torpedo tubes. Battery and generator busses in control cubicle arced, causing flame and smoke, and contactors were welded together by heat. Main power was secured. High pressure air line from No. 5 air bank carried away between hull and hull stop valve, allowing bank to bleed down. JK-QC sound projector was damaged on grounding. Access hatch trunks flooded in engine room and after battery compartment. Other minor damage occurred. Ship remained on patrol. |
--293--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
BERGALL (SS320) |
6/13/45 (5th) |
Gulf of Siam |
Mine - 1 |
Swept U.S. or British proximity-fuzed mine while surfaced. See Section XI for detailed account. Ship terminated patrol as result of damage. |
PARCHE (SS384) |
6/26/45 |
Off Northern Honshu |
Depth Charges - 67 |
Depth charged by six Japanese CHIDORI and SC escorts. 16 close charges detonated below ship while running at about 300 foot depth. No. 2 sanitary tank flooded completely through outboard vent valve which jarred open. Inboard vent had not been closed and considerable flooding occurred in crews' mess and washroom through this line. Boat went to 550 foot depth with 8° up angle. Noise level from shafts and reduction gears increased. Bendix log, dead reckoning analyzer indicator, and Mk. VII gyro compass follow-up alarm system were deranged. Both sonar training motors flooded with bilge water due to up angle on boat. Inboard flapper valve of 5-inch ammunition scuttle jarred open as much as 3 inches with each close charge. Other minor damage occurred. Ship remained on patrol. |
HAWKBILL (SS366) |
7/18/45 |
Off Malay States, South China Sea |
Depth Charges |
While at periscope depth, KAMIKAZE Class destroyer passed directly overhead and dropped close depth charge pattern which detonated under ship. Auxiliary power was lost at once. Ship broached with 20° up angle, exposing 60 feet of the hull forward with bow 20 feet above surface. HAWKBILL immediately re-submerged by backing with full power and flooding negative tank Main motors were then secured and boat was put on the bottom in 110 feet of water. No additional close attacks were received. Knock developed in starboard reduction gear. Low power optics of No. 2 periscope were deranged. Lobe switching failed on SJ radar. SD transmitter and SD antenna mast limit switches were damaged. Controller and starting resistance for JC-QC sound gear training motor were put out of commission. Bathythermograph was damaged beyond repair. Mercury was displaced from both master and auxiliary gyrocompasses and electrical leads to master compass were severed. Both radio receivers and TBL transmitter were deranged. One main storage battery cell cracked, resulting in loss of electrolyte. Many light bulbs broke and various meters and gauges were deranged. Other minor damage occurred. Patrol was terminated. |
--294--
NAME |
DATE |
PLACE |
SOURCE |
REMARKS |
CERO (SS225) |
7/18/45 |
Off Kurlle Islands |
Bomb - 1 |
Received one light bomb from Japanese GRACE aircraft while submerging and passing 43 feet. No. 1 periscope was put out of commission. Bridge "covered wagon" structure was distorted slightly and bridge deck buckled. Bridge instruments were disabled. Mercury was displaced from auxiliary gyro compass. Miscellaneous other minor damage occurred. Patrol was terminated. |
PARGO (SS264) |
7/27/44 |
Off Northern Celebes |
Bombs - 2 |
Received one bomb from Japanese PETE aircraft while at periscope depth, and a second bomb while going deep. During next 1 1/2 hours two Japanese CM's dropped about 48 depth charges on PARGO while running at deep submergence. No. 2 sanitary tank flooded. Radio antenna trunk flooded through broken insulator. Electrical interlock on bow plane tilting circuit was deranged so that planes could not be rigged. Overspeed trips on Nos. 1 and 2 turbo-blowers opened. Outboard exhaust valve on No. 4 main engine jammed. Auxiliary gyrocompass displaced mercury. Numerous gauges, instruments and light bulbs were broken or deranged and other minor damage occurred. Ship remained on patrol. |
MUSKALLUNGE (SS262) |
3/8/45 |
Off Kurile Islands |
Gunfire (.30 cal.) |
Received several .30 caliber projectile hits during gun action with a group of seven Japanese sea trucks. Average range during engagement was about 350 yards. Only materiel damage caused, other than numerous penetrations of superstructure plating, was the holing of a periscope hydraulic cylinder by two projectiles. Ship remained on patrol. |
--295--
APPENDIX II
Tabular Summary of U.S. Submarine Losses During World War II
1. A tabular summary of all United States submarine losses incurred throughout World War II is presented on the following pages. This summary is based upon information contained in the publication entitled "U. S. Submarine Losses, World War II" prepared by the Commander Submarine Force, Pacific Fleet, and ComSubPacAdmin ltr. FF12-10(A)/A16-2, Serial No. 00349 of 21 September 1945 (Statements of Survivors of U. S. Submarines Lost in Action). In arriving at the conclusions set forth in the referenced publication regarding the circumstances of each submarine loss, all of the following sources were considered:
(a) The operation order delineating each submarine's mission and assigned patrol areas.
(b) Dispatches sent to and received from each submarine during the patrol on which lost.
(c) Reports of Allied aircraft, surface ships ana submarines, particularly those operating in conjunction with the lost submarine as a coordinated attack group, containing mention of contacts, rendezvous, submarine actions against enemy shipping, enemy anti-submarine attacks, or other evidence which might indicate the presence of the submarine concerned or furnish information on its loss.
(d) Reports of enemy or Allied mines in the assigned patrol areas or routes to and from those areas.
(e) Statements of survivors, repatriated prisoners of war and friendly guerilla forces.
(f) A list of anti-submarine attacks provided by the Japanese upon termination of the war.
2. Source (f), the list of Japanese anti-submarine attacks made during World War II, consists of two sections, both supposedly exact translations, and contains only those actions which the Japanese assessed as resulting in positive sinkings. The first section gives the date and location of each attack; the second section contains brief amplifying comments on certain attacks, particularly those made after July 1943 when the Japanese claim to have commenced more rigid investigation of reported sinkings. In many cases no
--296--
information is available as to whether the attacks were made by surface ships, planes or submarines. Unfortunately, those attacks which were thought to be ineffective, or whose dates or locations were uncertain, were not recorded by the Japanese. In addition, there are many anti-submarine attacks that are known to have occurred, including several cases where our submarines were lost and survivors were captured by the Japanese, which are not contained in the list since apparently either no report was ever made to a central Japanese agency or the attacking ships or planes were themselves lost before returning to base. It should be borne in mind that one or more of these unrecorded attacks might better explain the loss of certain submarines which in the summary below have been attributed to other attacks, mines, or for which no known attack could conceivably have applied. However, the Japanese were prone to accept the most inconclusive evidence as proof of a sinking and for that reason their list is probably fairly complete. For example, it contains a total of 468 "positive" sinkings, whereas at most only 41* U.S. submarine losses were due directly to Japanese action, including passive means such as mines. Where only one listed attack could be tied in with a submarine loss, in the absence of better information it has been designated in the tabular summary below as the probable cause of the loss.
3. The geographical locations given in the summary correspond with those attacks or other information on which the explanation of the loss of each submarine is based. However, several submarines departed from their bases and were never heard from again nor is any information available as to their loss. For such cases the estimated position is given as inside the area to which the submarine was assigned but the loss might have occurred anywhere between that area and the base.
4. It is to be expected that further data may become available in the future which will modify some of the conclusions presented below.
5. For the purpose of indicating the accuracy of the conclusions reached for each submarine loss in the summary, integers have been placed after the name of each submarine with meanings as follows:
1 - Certain (based upon survivors' reports or known schedule of training operations).
2 - Probable (based upon strong circumstantial evidence obtained from one or more of the sources enumerated in paragraph (1) above).
3 - Possible (based upon inconclusive circumstantial evidence obtained from one or more of the sources enumerated in paragraph (1) above).
4 - Conjecture (a possible hypothesis advanced in the absence of any applicable circumstantial or direct evidence but based on the known presence of mines in the submarine's assigned patrol area).
5 - Unknown (no information available).
* U.S. Submarine Losses, World War II
--297--
NO. |
SS NO |
NAME |
DATE OF LOSS |
LOCATION OF LOSS |
CAUSE OF LOSS |
REMARKS |
1 |
195 |
SEALION 1 |
12/10/41 |
U.S. Navy Yard, Cavite, P.I. |
Bombs - 2 |
Struck by two small bombs during Japanese aircraft attack on Navy Yard, Cavite. First bomb detonated in conning tower fair-water a few feet above pressure hull, demolishing conning tower after bulkhead and engine air induction and battery ventilation trunks. Pressure hull over control room was pierced by numerous fragments. Second bomb penetrated pressure hull and detonated inside after engine room causing that space to flood rapidly. Forward engine room and after torpedo room flooded slowly through bulkhead fragment holes. Stern sank to bottom. Repair facilities not being available, SEALION was blown up 25 December 1941 to prevent capture by Japanese forces. |
2 |
141 |
S-36 1 |
1/20/42 |
Makassar Strait |
Stranding |
Stranded on Taka Bakang Reef off southern Celebes. Forward battery room was holed and flooded, causing generation of chlorine gas. Ship was abandoned and destroyed by U.S. forces on 21 January 1942. |
3 |
131 |
S-26 1 |
1/24/42 |
Gulf of Panama |
Collision |
Collided with PC-460 while surfaced and enroute to patrol area. Starboard side of torpedo room was holed. Ship sank in 300 feet of water within a few seconds. The three and only survivors were on bridge at time of collision. |
4 |
174 |
SHARK (I) 3 |
2/11/42 to 2/21/42 |
Off Celebes |
Depth Charge |
Last heard from on 7 February 1942. Japanese records indicate three attacks, one or more of which may have accounted for loss of SHARK. The first and most likely attack was that by surface ship off Menado, Celebes, on 11 February 1942. The second was north of Kendari, Celebes, on 17 February 1942 and the third was east of Kendari on 21 February 1942. |
5 |
176 |
PERCH 1 |
3/3/42 |
Java Sea |
Depth Charge |
Scuttled by own crew after Japanese depth charge attacks. See Section IV for details of loss. |
6 |
132 |
S-27 1 |
6/19/42 |
Off Amchitka, Aleutian Islands |
Stranding |
Stranded on reef 400 yards off Amchitka Island. Torpedo room flooded. After battery room made water and chlorine gas was generated. Ship assumed 8 to 12 degrees trim by the bow after grounding. Ship was abandoned. |
7 |
216 |
GRUNION 5 |
7/30/42 to 8/6/42 |
Off Aleutian Islands |
Unknown |
Last heard from on 30 July 1942 off Kiska at which time she reported strong Japanese anti-submarine activity. On the same day, GRUNION was directed to return to Dutch Harbor and should have arrived by 6 August 1942. No explanation of loss Is available from Japanese sources. |
8 |
144 |
S-39 1 |
8/14/42 |
Off Rossel Island, Louisiade Archipelago |
Stranding |
Stranded on submerged reef. Ballast tanks were ruptured by pounding in heavy seas and ship assumed 60 degrees port list. Ship was abandoned. |
9 |
APS 1 |
ARGONAUT 2 |
1/10/43 |
Off New Britain, Bismarck Archipelago |
Depth Charge and Gunfire |
U.S. Army bomber observed ARGONAUT forced to surface by depth charge attack of Japanese destroyers and sunk by gunfire. Action occurred off New Britain on 10 January 1943. |
10 |
219 |
AMBERJACK 3 |
2/16/43 |
Off New Britain, Bismarck Archipelago |
Bomb and Depth Charge |
Last heard from on 14 February 1943. Japanese records indicate several attacks any one of which might have accounted for loss of AMBER JACK. The most likely action was a. combined attack by one patrol plane and two surface escorts on 16 February 1943. It was reported that a large amount of oil and "parts of the hull" came to the surface. |
--298-- / --299--
NO. |
SS NO. |
NAME |
DATE OF LOSS |
LOCATION OF LOSS |
CAUSE OF LOSS |
REMARKS |
11 |
207 |
GRAMPUS 5 |
3/6/43 |
Blackett Strait, Solomon Islands |
Gunfire |
Never heard from again after departing Brisbane, Australia on 12 February 1943. Japanese records indicate two attacks, either of which might have accounted for loss of GRAMPUS. However, on the basis of other evidence, It appears more likely that she was caught on the surface by Japanese destroyers passing through Blackett Strait on the night of 5-6 March and was sunk by gunfire. Since the destroyers were themselves subsequently sunk, Japanese reports contain no mention of such an attack. |
12 |
201 |
TRITON 2 |
3/15/43 |
North of New Guinea |
Depth Charge |
Last heard from on 11 March 1943. Japanese information indicates that TRITON was almost certainly sunk by depth charge attack of Japanese destroyers on 15 March 1943. It was reported that "a great quantity of oil, pieces of wood, cork and manufactured goods bearing the label 'Made in U.S.A.' " was sighted after the attack. |
13 |
177 |
PICKEREL 3 |
4/3/43 |
Off Northern Honshu |
Depth Charge |
Never heard from again after departing Midway on 22 March 1943. Japanese information indicates PICKEREL was possibly sunk by depth charge attack off Shiramuka. Lighthouse, Honshu on 3 April 1943. |
14 |
210 |
GRENADIER 1 |
4/22/43 |
Off Penang, Malaya |
Bomb |
Scuttled by own crew after aircraft bomb attack. See Section VIII for details of loss. |
15 |
89 |
R-12 1 |
6/12/43 |
Off Key West, Florida |
Operational or Materiel Casualty |
Lost during training exercises off Key West, Florida. While surfaced, rapid flooding occurred forward for unknown reasons and the boat sank In about 15 seconds. The five officers and men on the bridge were the only survivors. The opinion of the Court of Inquiry was that the flooding could not be traced to any known cause but probably occurred through a torpedo tube. |
16 |
275 |
RUNNER 4 |
5/28/43 to 7/4/43 |
Off Northern Honshu |
Mine |
Never heard from again after departing Midway on 28 May 1943. Japanese records indicate no attacks which could conceivably have accounted for loss of RUNNER. It is considered possible that she may have been destroyed by a mine for there were at least four known minefields in her assigned patrol area. |
17 |
209 |
GRAYLING 5 |
9/9/43 to 9/12/43 |
Off Manila, P.I. |
Unknown |
Last heard from on 23 August 1943. Japanese records indicate no attacks which could conceivably have accounted for loss of GRAYLING. |
18 |
181 |
POMPANO 4 |
8/20/43 to 9/27/43 |
Off Northern Honshu |
Mine |
Never heard from again after departing Midway on 20 August 1943. Japanese records indicate no attacks which could conceivably have accounted for loss of POMPANO. It is considered possible that she may have been destroyed by a mine for her assigned patrol areas were known to have been heavily mined. |
19 |
290 |
CISCO 3 |
9/28/43 |
Sulu Sea |
Bomb and Depth Charge |
Never heard from again after departing Port Darwin, Australia on 19 September 1943. Japanese records indicate that CISCO may have been sunk in the Sulu Sea. by combined aircraft and surface ship attack on 28 September 1943. It was reported that "oil continued to gush out even on tenth of October", |
20 |
155 |
S-44 1 |
10/7/43 |
Off Kamchatka, Okhotsk Sea |
Gunfire |
While surfaced at night, S-44 opened fire with her deck gun on a target believed to be a small enemy merchant ship but which actually was a Japanese destroyer. The immediate and accurate return fire of the destroyer sank S-44 before she could escape by submerging. About eight men escaped before the boat went under but only two of these were rescued. |
--300-- / --301--
NO. |
SS NO |
NAME |
DATE OF LOSS |
LOCATION OF LOSS |
CAUSE OF LOSS |
REMARKS |
21 |
238 |
WAHOO 3 |
10/11/43 |
La, Perouse Strait, Sea of Japan |
Bomb |
WAHOO was never heard from again after departing Midway on 13 September 1943, although she is known to have sunk a Japanese ship in the Sea of Japan near the Straits of Tsushima on 5 October 1943. Japanese information indicates that she was possibly sunk by aircraft attack on 11 October 1943 while passing through La Perouse Strait on her way out of the Sea of Japan. |
22 |
248 |
DORADO |
10/12/43 |
Off U.S. East Coast |
Unknown |
Never beard from again after departing Submarine Base, New London on 6 October 1943 for Panama Canal. There were no definite conclusions as to the cause of loss. Possible causes could have been operational casualties, enemy action, or attack by friendly forces. |
23 |
226 |
CORVINA 2 |
11/16/43 |
South of Truk |
Torpedo (Sub.) |
Never heard from again after departing Johnston Island on 6 November 1943. Japanese records Indicate that CORVINA was torpedoed while surfaced by a Japanese submarine. Two of the three torpedoes which were fired were reported to have hit. |
24 |
191 |
SCULPIN 1 |
11/19/43 |
North of Truk |
Depth Charge |
While preparing to attack a Japanese convoy on the night of 18 November 1943, SCULPIN was detected by Japanese destroyers and depth charged. The first series of depth charges caused only minor damage. The ship then broached when the diving officer attempted to plane up to periscope depth, the depth gage having stuck at a reading of 125 feet, and the enemy destroyers renewed the attack at once. About noon on 19 November, another series of depth charges damaged SCULPIN severely. The pressure hull was dished in, torpedo tube bulkheads were cracked, valves leaked, bow and stern planes were damaged and the boat was badly out of trim, about 180 shaft r.p.m. being required to maintain depth control. The boat at this time went to a reported maximum depth of about 500 feet. With batteries rapidly nearing depletion and the crew exhausted, SCULPIN was then forced to make a battle surface. When in the ensuing gun action it became apparent that escape was impossible, the ship was scuttled by diving at emergency speed with all vents open. Forty-two men abandoned ship before SCULPIN sank and of these, twenty-one survived the end of the war. |
25 |
289 |
CAPELIN 3 |
11/23/43 to 12/9/43 |
Off Halmahera, Moluccas |
Depth Charge |
Never heard from again after departing Port Darwin, Australia on 17 November 1943. Japanese records list an attack on a U.S. submarine off Kaoe Bay, Halmahera, on 23 November 1943, but the action was Incomplete and evidence of contact was slight. However, this is the only reported attack which could possibly have caused the loss of CAPELIN. |
26 |
SS278 |
SCORPION 4 |
1/5/44 to 2/24/44 |
Yellow Sea |
Mine |
Last heard from during rendezvous with HERRING (SS233) on 6 January 1944. Japanese records indicate no attacks which could conceivably have accounted for loss of SCORPION. It is considered possible that she may have been destroyed by known minefields at the entrance to the Yellow Sea while proceeding to or departing from her assigned patrol area. |
27 |
208 |
GRAYBACK 2 |
2/26/44 |
Off Okinawa |
Bomb and Depth Charge |
Last heard from on 25 February 1944. Japanese records indicate that GRAYBACK was probably sunk on 26 February by the combined attack of a. carrier plane and surface escorts. It was reported that the plane sighted a surfaced U.S. submarine and "gave a direct hit at the sub, which exploded and sank immediately". |
--302-- / --303--
NO. |
SS NO. |
NAME |
DATE OF LOSS |
LOCATION OF LOSS |
CAUSE OF LOSS |
REMARKS |
28 |
202 |
TROUT 2 |
2/29/44 |
Philippine Sea |
Depth Charge |
Japanese records list the sinking of SAKITO MARU on 29 February 1944 in position 22°-40'N, 131°-45'E in the Philippine Sea. TROUT is the only U.S. submarine which could have made this attack and since she did not report the sinking, it is probable that she was lost during or shortly after this action. |
29 |
284 |
TULLIBEE 1 |
3/26/44 |
Off Palau Islands |
Own Torpedo |
According to the one lone survivor, a minute or two after firing two torpedoes at a target ship on the night of 26 March 1944, TULLIBEE was damaged by a heavy explosion and sank immediately. Although there is no conclusive evidence, it is considered quite likely that the explosion was caused by a circular run of one of TULLIBEE's own torpedoes. |
30 |
211 |
GUDGEON 5 |
4/7/44 to 5/12/44 |
Off Marianas Islands |
Bomb and Depth Charge |
Never heard from again after departing Johnston Island on 7 April 1944. Japanese records indicate at least two attacks which might have accounted for loss of GUDGEON but the information furnished is too limited to permit any conclusions. Heavy anti-submarine activity, both aircraft and surface ship, was noted by SILVER-SIDES (SS236), TUNNY (SS282) and SANDLANCE (SS381) off the Marianas Islands on 12 May 1944 slightly to the south of GUDGEON'S assigned area and it is possible that these attacks were responsible for her loss. |
31 |
233 |
HERRING 2 |
6/1/44 |
Off Matsuwa To, Kurile Islands |
Gunfire |
Last heard from during rendezvous with BARB (SS220) on 31 May 1944. Japanese information indicates that HERRING was sunk on 1 June 1944 by gunfire from shore batteries shortly after torpedoing two merchant ships anchored at Matsuwa. The report stated that two direct hits were scored on the conning tower and that "bubbles covered an area about 5 meters wide, and heavy oil covered an area, of approximately 15 miles". |
32 |
361 |
GOLET 2 |
6/14/44 (2nd Patrol) |
Off Northern Honshu |
Depth Charge |
Never heard from again after departing Midway on 28 May 1944. Japanese information indicates that GOLET was probably sunk off Northern Honshu by surface ship attack on 14 June 1944. It was reported that "corks, raft, etc., and a heavy oil pool" were found at the scene of the action. |
33 |
133 |
S-28 1 |
7/4/44 |
Off Oahu, T. H. |
Operational or Materiel Casualty |
Lost while on training exercises off Oahu, T.H. Submerged and never resurfaced. Nature of casualty which caused loss is unknown. |
34 |
273 |
ROBALO 1 |
7/26/44 |
Balabac Strait |
Mine |
Information contained in a note written by survivors of ROBALO, none of whom lived to the end of the war, and also from a Philippine guerilla leader, indicates that ROBALO was sunk on 26 July 1944 while east of Balabac Island. The note stated that the sinking was caused by explosion of the after battery. It is believed more likely, however, that ROBALO was mined. No Japanese information is available. FLIER (SS250) was also apparently mined in this same area two weeks later. |
35 |
250 |
FLIER 1 |
8/13/44 |
Balabac Strait |
Mine |
Explosion occurred forward while proceeding on the surface through Balabac Strait on the night of 13 August 1944. Ship is reported to have sunk in 20 or 30 seconds. About 15 men abandoned ship before she sank and of these only eight were able to swim ashore and survive. Explosion is believed to have been contact mine. |
36 |
257 |
HARDER 2 |
8/24/44 |
Off Luzon South China Sea |
Depth Charge |
Information received from both the Japanese and HAKE (SS256) indicates that HARDER was sunk by depth charge attack off central Luzon on 24 August 1944. The Japanese report stated that "much oil, wood chips and cork floated in the neighborhood". |
--304-- / --305--
NO. |
SS NO, |
NAME |
DATE OF LOSS |
LOCATION OF LOSS |
CAUSE OF LOSS |
REMARKS |
37 |
197 |
SEAWOLF 5 |
10/3/44 |
Off Halmahera, Moluccas |
Unknown |
Assessment of all available information does not establish cause of loss but indicates the possibility that the ship may have been lost during anti-submarine attacks on a Japanese submarine. |
38 |
294 |
ESCOLAR 4 |
10/17/44 to 11/3/44 |
East China Sea |
Mine |
Last heard from on 17 October 1944. No explanation of loss Is available from Japanese sources. No other information being available, it is presumed that ESCOLAR's loss was caused by a mine for these are known to have been present in her assigned patrol area. |
39 |
306 |
TANG 1 |
10/24/44 |
Formosa Strait |
Own Torpedo |
Sunk by circular run of own torpedo. See Section X for details of loss. |
40 |
314 |
SHARK (II) 2 |
10/24/44 |
South of Formosa |
Depth Charge |
Last heard from on 24 October 1944. Japanese information indicates that SHARK was probably sunk by depth charge attack south of Formosa on 24 October 1944, shortly after torpedoing a Japanese transport. It was reported that "bubbles, and heavy oil, clothes, cork, etc.," were sighted. |
41 |
227 |
DARTER 1 |
10/24/44 |
Bombay Shoal, South China Sea |
Stranding |
Ran aground on Bombay Shoal, South China Sea on 24 October 1944 while running surfaced at 17 knots speed. Crew abandoned ship and partial destruction was carried out by gunfire from DACE (SS247) and NAUTILUS (SS168) to prevent possible enemy utilization. |
42 |
218 |
ALBACORE 2 |
11/7/44 |
Off Northern Honshu |
Mine |
Never heard from again after departing Midway on 28 October 1944. Japanese information indicates ALBACORE was sunk by mine while running submerged off northern Honshu on 7 November 1944. Both the explosion and the resulting debris were witnessed by an enemy patrol craft. |
43 |
215 |
GROWLER 2 |
11/8/44 |
Off Mindoro, P.I. |
Depth Charge |
Believed to have been sunk while attacking a Japanese convoy off Mindoro, P.I., on 8 November 1944. Information furnished by HAKE (SS256) and HARDHEAD (SS365), who were operating with GROWLER at the time, indicates that the loss may have occurred either as a result of enemy depth charging or the malfunctioning of one of GROWLER'S own torpedoes, but no conclusive evidence exists. No Japanese information is available. |
44 |
277 |
SCAMP 5 |
11/9/44 to 11/16/44 |
Off Tokyo Bay |
Bomb and Depth Charge |
Last heard from on 9 November 1944. Japanese records list three attacks, one or more of which may possibly have accounted for loss of SCAMP while assigned to aviator rescue duty off Tokyo Bay. On 11 November 1944, a Japanese patrol plane bombed what appeared to be oil trails left by a submarine and a coast defense vessel dropped some seventy depth charges in three runs on the same target whereupon a. large oil pool was reported to have appeared. On 16 November two attacks in SCAMP's area were made, during one of which it was reported that "great explosive sounds came as a result of this attack". |
45 |
193 |
SWORDFISH 3 |
1/12/45 |
Off Okinawa |
Depth Charge |
Last heard from on 3 January 1945. Information furnished by KETE (SS369) indicates that SWORDFISH may have been sunk by Japanese depth charge attack near Okinawa on 12 January 1945. No explanation of loss is available from Japanese sources. |
46 |
316 |
BARBEL 2 |
2/4/45 |
Off North Borneo |
Bomb |
Last heard from on 3 February 1945. Japanese information indicates that BARBEL was probably sunk by aircraft attack off North Borneo on 4 February 1945. It was reported that one of the two bombs struck near the bridge. |
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NO. |
SS NO |
NAME |
DATE OF LOSS |
LOCATION OF LOSS |
CAUSE OF LOSS |
REMARKS |
NO. 47 |
369 |
KETE 5 |
3/20/45 to 3/31/45 |
Off Nansei Shoto Islands |
Unknown |
KETE had been directed to depart her patrol area in the vicinity of the Nansei Shoto Islands on 20 March and proceed to Pearl for refit. Receipt of these orders was acknowledged on 19 March and on 20 March KETE sent a. special weather report, the last message received from her. At normal cruising speed she should have arrived at Midway about 31 March 1945. No possible explanation of loss is available from Japanese sources. |
48 |
237 |
TRIGGER 2 |
3/28/45 |
Off Southern Kyushu |
Bomb and Depth Charge |
Last heard from on 26 March 1945. Japanese records and information furnished by THREADFIN (SS410) and three other U.S. submarines indicate that TRIGGER was probably sunk as a result of a combined attack by planes and surface vessels off southern Kyushu on the afternoon of 28 March 1945. The Japanese report stated "Found oil pool of 1 x 5 miles in size the following day". |
49 |
279 |
SNOOK 5 |
4/8/45 to 4/20/45 |
South China Sea or off Formosa |
Unknown |
Last heard from on 8 April 1945 during rendezvous with TIGRONE (SS419) near Hainan Island in the South China Sea. No explanation of loss is available from Japanese sources. |
50 |
371 |
LAGARTO 2 |
5/3/45 |
Gulf of Slam |
Depth Charge |
Last heard from on 3 May 1945. Japanese records and information furnished by BAYA (SS318) indicate that LAGARTO was probably sunk by depth charge attack In the Gulf of Siam on 3 May 1945 while attempting to attack a Japanese convoy. |
51 |
223 |
BONEFISH 2 |
6/18/45 |
Off Central Honshu, Sea of Japan |
Depth Charge |
Last heard from during rendezvous with TUNNY (SS282) on the morning of 18 June 1945. At this time BONEFISH received permission to conduct a submerged daylight patrol off Toyama. Wan on the west coast of Honshu and she Immediately departed for that area. Japanese information indicates that she was sunk there on 18 June as a result of depth charge attack. Wood chips and oil were observed after the attack. |
52 |
332 |
BULLHEAD 2 |
8/6/45 |
Java Sea |
Bomb |
Of the many Japanese anti-submarine attacks recorded as having been made in BULLHEAD'S patrol area in the Java Sea during the period she could have been present, the one believed most likely to have accounted for her loss was that on 6 August 1945 by Japanese army planes. It was reported that two direct hits were made and that for the next ten minutes a large quantity of oil and air bubbles rose from the scene of the attack. |
--308-- / --309--
Appendix III