Pontoon Causeway Operating Instructions
Section 1. References
- Pontoon Gear Manual, dated August 1943.
- ComLanCraftNaw "Pontoon Causeway Operating Instructions", dated 22 August 1943.
- FTP 214A. LST OPERATIONAL INFORMATION, published by BuShip dated 25 March 1943.
Section 2. General
- 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.
- 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.
- 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.
- 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
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.
- 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:
- 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.
- 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.
- 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.
- 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.
- 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.
- 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
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.
- 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.
- Transporting Causeways.
- 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).
- 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.
- The Causeways are fitted with towing pad-eyes, bits, towing bridle, chaffing gear, etc., and the inshore unit is rigged with a ramp.
- 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.
- 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.
- 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
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.
- Beaching Causeways:--
- 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.
- 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.
- 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.
- 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.
- The haulback cable is pulled to the Causeway by means of the messenger line and secured to a pad-eye.
- 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.
- 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
around on haulback cable utilizing the elevator or anchor winch.
- 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.
- 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.
- 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.
- Under average conditions the total operation may be completed within 30 minutes following the grounding of LST.
- 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
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.
- 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.
- 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.
- 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.
- 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.
- 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").
- 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.
- 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.
- 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.
- Other Uses for Causeways:--
- 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.
- 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.
- 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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