Chapter XV
Pontoon Causeway Operating Instructions
Section 1. References
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Pontoon Gear Manual, dated August 1943.
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ComLanCraftNaw "Pontoon Causeway Operating Instructions",
dated 22 August 1943.
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FTP 214A. LST OPERATIONAL INFORMATION, published by BuShip
dated 25 March 1943.
Section 2. General
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Purpose of Pontoon Causeways:--Pontoon causeways provide a
bridge or link between the beach and the Landing Ships and Craft
beached off-shore and furnish a means of rapidly discharging
cargo from the Landing Craft.
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Duties and Responsibility:--The Commanding Officer of the ship
carrying the causeway bears the initial responsibility in rigging
the bridge in accordance with instructions set forth below.
The SeaBee causeway detail embarked consists of two officers and
thirty-four men. The function of this detail is to handle,
assemble, place and maintain the causeway as well as to perform
necessary salvage work on damaged causeways. This unit is quartered
and messed aboard ship until the beachhead is established,
and then it becomes a part of the Amphibious Force shore party.
The Commanding Officer of the ship and the SeaBee Officer must
cooperate and must make certain that all personnel under their
respective commands work together as a team. The authority for
the location of the causeways and the movement thereof is vested
in the Senior Beachmaster. The Officer-in-Charge of the Pontoon
Causeway Detachments will take his orders from the Senior Beachmaster,
or his duly authorized representative, concerning such
location and movement. The Senior Beachmaster should, however,
consult with the causeway personnel and take advantage of their
experience in such matters.
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Pontoon Causeways:--A set of Pontoon Causeways, in general, consists
of a pair of steel barges 14' x 175' each unit being called
a Causeway. They are made of standard Navy Steel pontoons and
assembly angles; each causeway weighs approximately 100 tons.
With them it is possible to construct a ship to shore bridge 14
feet wide and up to 325 feet in length, over which any type Army
vehicle may be speedily unloaded.
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Trim and Load of LSTs:--The beaching drafts of LSTs is determined
by tonnage of cargo carried and the condition of the ballast
tanks. Beaching drafts based upon reconnaissance will be furnished
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to all LSTs prior to the operation by proper authority. It is
the responsibility of all LST Captains to obtain this information and
to secure the proper drafts.
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Hoisting Causeway:--Causeways are carried on the sides of the LSTs and
transported in this manner to the scene of operations. When so carried,
the causeways will not affect the speed or maneuverability of the ship
to any great extent. Where cranes of sufficient capacity are not
available for the hoisting, the following procedure shall be used:
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The LSTs designated to carry causeways are equipped with brackets
on their sides and pad-eyes welded to the deck to which hoisting
tackle may be attached. "U" hooks are welded to the gunwale from
which turnbuckles, which assist in holding the hoisted causeways
in place, may be hooked.
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The hoisting gear and personnel for hoisting are supplied by the
SeaBee platoon. The ship's anchor winch and cable are utilized
during hoisting and it may be necessary to use some of the ship's
vehicle lashing chains to secure the causeways in place. While
the rigging is done by the SeaBee Platoon the ship's Commanding
Officer shall supervise the hoisting and lend such assistance as
may be necessary.
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The hoisting of the causeways must be done in sheltered waters
free from ground swells and waves. The ship may be anchored using
the bow anchor or tied up, but it is preferred to have access
to both sides of the ship.
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The rigging for hoisting is roughly as follows: two 11/4" wire
slings are made fast to the causeway in the form of a rolling
hitch and giving support to the causeway at four points. Each
sling is fastened to a five part, one inch steel cable, block
and tackle which is anchored to the pad-eyes welded to the deck
for this purpose. Power for hoisting is supplied by the stern
anchor winch, the cable of which is passed through a series of
snatch blocks and attached to the one inch steel cables from
the hoisting tackle.
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Before hoisting the ship must be listed to an angle of approximately
7 degrees to permit the rocker arms on the sides of the
causeway to rest on the brackets welded to the sides of the
ship. Then by heaving round on the stern anchor winch the causeways
are hoisted to the side of the ship. In their hoisted
position the causeways are on edge with their deck against the
side of the ship and the upper edge of the causeway approximately
four feet above the ship's deck.
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They are made fast in this position by means of 3/4" vehicle
lashing chains attached by a turnbuckle to the clover leaves on
the deck of the ship. Past practice has indicated that three
pairs of chain in the form of an X, three straight chain ties
and a chain around the bridge stanchion are ample to hold the
causeway in a fairly rough sea. The three straight chains
are each attached to the causeway by means of a short length
of 5/8" steel cable. A chopping block is rigged under
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short lengths of cable as the causeways are launched
by the simultaneous cutting of these cables. Tension
is applied to the chain ties by wedges placed
between the deck of the causeway and the side of the
ship and by taking up on the turnbuckles attached to
the clover leaves.
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In order to launch the causeways all ties are removed
from each causeway except the three straight ties
contain the chopping cables. Men with axes are
then stationed adjacent to each cable, and upon a
previously arranged signal simultaneously cut the cables.
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Transporting Causeways.
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SIDE CARRY METHOD. This is the preferred method.
The Causeways are hoisted on the sides of LSTs. On
arrival in the Transport Area, the chains and turnbuckles
are removed, and the Causeways dropped to
position. The port Causeway "A" is then passed
around by maneuvering the ship to position. The
SeaBee Platoon, meanwhile, loads its gear and equipment
onto the Starboard Causeway "B" and makes necessary
preparations (for beaching).
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TOW METHOD. The two causeways are towed as a rigidly
connected steel barge 28' x 175'. The units
are connected together by means of fittings specially
designed for quick uncoupling.
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The Causeways are fitted with towing pad-eyes,
bits, towing bridle, chaffing gear, etc., and
the inshore unit is rigged with a ramp.
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The towing ship must be equipped with a towing
wire at least 1-5/8 inches in diameter. The
towing ship will carry the SeaBee Platoon
assigned to the Causeway together with their
equipment and gear.
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When towed by tug, on arrival at the Transport
Area, the tug should slow down to steerage way
and the towing wire hauled in until the tow is
about 40' astern. The tug should hold the
tow along its port side. After the Causeways
are alongside, the Seabee Platoon should be
put aboard it, and preparation made for coming
alongside the starboard side of the LST designated
to receive and beach them. Before
actual beaching, the SeaBees will disengage
the temporary fastenings and secure the Causeways
to the LST.
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Beaching of LST:--The "Beaching Instructions" in the LST
Special Operations Instruction Book, requires a beaching
speed of 5 or 6 knots. Continued beaching operations indicates
that the beaching speed should be 7 or 8 knots
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as this latter speed gives a better runup and little
difficulty has been experienced with retraction. Speed
of 7 to 8 knots shall be used in landing. About 200
yards from shore the stern anchor should be dropped.
The bow doors must be fully opened for beaching.
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Beaching Causeways:--
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MOMENTUM METHOD. The LSTs assigned to beach Causeways
will leave the Transport Area for the beach
with the Causeways depending on whether they were
towed or carried.
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In either case, the beaching procedure is as
follows: The LST will proceed to the beach
at standard speed or better. This is very important
as this operation depends on the Causeways
having enough momentum to beach themselves
plus the fact that the ship may ground too
far off-shore for the Causeways to reach if
a timid approach is made.
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On order from the SeaBee Officer, the aft
breast line, the stern line, and the forward
breast line are cast off in that order leaving
only the tow cable. This should be completed
about 1000 feet before the LST grounds, the
tow wire becomes slack and is cast off from
the Causeway, the causeway proceeding to the
beach under its own momentum. In order that
the tow cable does not drop alongside and foul
on the rocker arms of the causeway, the end
should be hoisted to the deck of the LST by
means of light lines.
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As the off-shore end of Causeway "A" passes
the bow of the LST, the man tending the messenger line and the haulback cable should keep
it slack and clear until the Causeways beach.
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The haulback cable is pulled to the Causeway
by means of the messenger line and secured to a pad-eye.
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When the Causeway is beached, two anchors will
be carried ashore by men stationed on the Causeway
for that purpose. The anchors should be
placed at the Waterline and at an angle of
about 45 degrees with the Causeway, one to
port and one to starboard. The Causeway Officer
will determine the exact location of the
anchors, taking into consideration conditions
of wind and current. After anchors are placed,
anchor lines should be immediately hove taut
and belayed to prevent drifting of the Causeways.
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The snublines are then set and chains "A", "B"
and "C" loosened. The offshore end of Causeway
"A" is then hauled under the ramp by heaving
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around on haulback cable utilizing the elevator
or anchor winch.
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As the off-shore end is brought under the ramp,
a set of block and falls are rigged in such a
manner that the Causeways may be removed laterally,
so that the king pin can be fitted into
the socket under the ramp. The ramp is then
lowered over the king pin forming a pivot connection.
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While the above operation is underway, the
lap connection between the two causeway units
should be secured for traffic. In making
the lap connection, Chain "A" should be placed
first so that any slack may be taken up by
the turnbuckles in the "B" chains. The "C"
chains should be secured with some slack in
them so that when the two units move vertically
in relation to each other, the strain is taken
by buoyancy and not by the chains. The minimum
lap of the Causeway sections is five pontoons
to permit traffic to cross.
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Finally the ramp to the beach should be set,
thereby making the causeways ready for traffic.
There are several satisfactory methods of
handling and transporting the ramps. One
method is to lash the ramps using wire rope to
the sides of "B" Causeway, before launching.
In addition to the wire lashing a slack manila
line should be made fast to the ramps to provide
against a possible failure of the wire
tie during launching and towing. To place the
ramps following the beaching, the wire ties
are cut with an axe and the ramps floated around
into position for placing.
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Under average conditions the total operation may
be completed within 30 minutes following the
grounding of LST.
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Side Carry Beach Launching:--This method is to be used
when conditions in the Transport Area are unfavourable for
handling Causeways and it is calm on the Beach. It consists
of beaching the LST with Causeways still carried
on the side. After the LST is beached the Causeways
are dropped, and with the aid of a DUKW or Bulldozer,
the port Causeway is hauled toward the beach enough so
that it may be passed across the bow of the ship. It
is then hauled back along the out-board side of the starboard
Causeway. The two sections are secured to each
other and hauled to the beach. Under average conditions,
it will require approximately 45 minutes to prepare the
causeway for launching, plus an additional hour to establish
the ship to shore bridge. It should be kept in mind
that the causeways on the side increase the ship's draft
about 6 inches. Where beach conditions are such that it
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is not feasible to beach at sufficient speed to use the
momentum method -- as on hard coral reefs -- the causeway
may be launched offshore and towed to the beach by landing
craft. In this method three LCV(P)s, or similar
craft, are used. One boat takes a line from the end of
the causeway which is to be on the beach and the other
two are made fast to the causeway near the other end, or
on either side. The boat ahead provides the primary
motive power, while the two astern are used merely for
steering. At a safe distance from the beach the boat
ahead casts off its towing line and moves aside. The
causeway then beaches itself from momentum. The two steering
boats remain with the causeway until it is in place
and anchored, in order to keep the causeway from broaching.
Once the causeway is in place operations proceed
as if it were being moved by a newly beached LST, as outlined
in the following paragraph.
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Moving Plan:--This method has been developed for transferring
a Floating Causeway Bridge which is already established
from ship to shore to the next LST arriving at
the beach. The causeway is moved into its new position
along the off-shore end by means of a line from the second
LST and at the other end by a bulldozer and DUKW. Under
favorable weather conditions a loaded LST can be beached
approximately within 100 yards of the first LST. This
operation requires approximately 30 minutes.
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Position #1. The first LST has completed unloading
vehicles over the causeway. The causeway is secured
at the off-shore end to the LST ramp and the inshore
end is grounded on the beach. Bulldozer and DUKW are ashore.
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The second LST should beach about ten minutes before
the first LST has completed unloading. During this
time the Causeway Platoon Commander and a crew for
handling lines will proceed to the second LST in the
DUKW. The Platoon Commander will take his station
on the forecastle on the second LST. He will report
to the ship's Captain and communicate to him any
necessary information concerning the operation. He
will check to see that the LST ramp is in its proper
position, about five feet above the water, that the
haulback line from the second LST is run through the
fair-lead at the lip of the ramp, that the ship's
detail is in position to operate the elevator winch
and that the LST is firmly grounded by the bow.
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Position #2. As soon as the first LST has completed
unloading, the inshore anchors will be taken aboard
the causeway and replaced by lines to the bulldozer,
and also the DUKW if necessary.
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A strain will be taken and kept on the haul back
line by the second LST in order to shift the off-shore
end of the causeway into position under its ramp.
During this operation, the inshore end of the causeway
will be controlled by the bulldozer, but care
should be taken to see that all lines ashore from the
in-shore causeway are slack, at the start of this
operation to permit causeway to swing off beach.
After the off-shore end is under the ramp, the bulldozer
will shift the in-shore end along the beach into
its final position make the second LST ramp connection
and adjust lap if necessary (as specified in the "Side
Carry-Momentum Method").
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When extending the causeway, the inshore causeway unit
should be moved towards the beach by the bulldozer
after the off-shore end has been secured to the LST ramp.
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If it should be found that the causeway is too long,
time will be saved by placing the causeway at an angle,
not to exceed about 20 degrees with the axis of the
LST. If this position should be taken, the ship's
Captain should line his ship with the causeway to
the greatest extent practicable.
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The DUKW will assist in this operation wherever required.
The bulldozer should be on the beach to assist
traffic over in-shore ramp if necessary. It should
never be immobilized by using it as a shore anchor for the LST.
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Other Uses for Causeways:--
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Upon completion of the initial beaching of the causeways,
the Pontoon Causeway Detail will report to the
Beachmasters on their respective beaches as a part of
the Beach Party, for handling the pontoon causeways
and for such other construction work as may be possible,
in connection with the landing of material.
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Upon completion of their use in unloading assault and/or
garrison LSTs, the causeways may be moved as directed
by the Naval Base Commander and reestablished where
desired, for use as floating piers or wharves. The
causeways may be put to use intact in any manner desired
by the Naval Base Commander.
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Personnel of Pontoon Causeway Detail:--Personnel of Pontoon
Causeway Detail will be subsisted by the Assault Forces
during the assault phase of the operation and until base
facilities have been established for naval personnel. Thereafter,
until their departure, the Naval Base Commander will
arrange for their subsistence.
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