Landing Craft Assault - Design

Design

All landing craft designs (and landing ship designs for ships intended to beach) must find a compromise between two divergent priorities; the qualities that make a good sea boat are opposite those that make a craft suitable for beaching. The LCA keel was produced from Canadian rock elm which was treated with steam to make it pliable and then shaped using a keel block and wedges. Twenty-four mahogany latitudinal frame pieces were joined to the keel providing the overall structure. The craft had a hull built of double-diagonal mahogany planking. The sides were plated with "10lb. DHT" armour, a heat treated steel based on D1 steel, in this case Hadfield’s Resista ¼”. Steps were taken to ensure that the boat would not sink when swamped. In the bow section between the armoured doors and the ramp, each bulkhead was packed with 30 cubic feet (850 L) of Onazote buoyant material. The same Onazote packing was placed along both hull sides for the length of the well, and 42.5 cubic feet (1.20 m3) filled the aft compartment.

The LCA had a long central well section fitted with three benches, one centre, one each port and starboard, for seating troops. The side benches were covered by the top deck. The well was divided from the bow by a bulkhead fitted with two vertically hinged doors. This pair of forward-opening armour-plate doors lead to the ramp, which was lowered and raised by a simple arrangement of pulleys and wire. Two rollers on the leading outboard edge providing some freedom of movement for the ramp when it was grounded. Over this ramp troops could come ashore in two to three minutes, or less if the soldiers and crews were well trained. Immediately behind the bulkhead were the steering shelter on the starboard, and the Lewis gun shelter on the port. The steering shelter was fitted with a telegraph and voice pipe for communication with the stoker, a featherspray control lever, and a fold-up seat. The shelter was protected on all four sides by non-magnetic bulletproof plate surmounted by a hinged double-door roof. Most LCAs were fitted with a compass.

Drive was by two shafts from the pair of Ford V8 engines to two 19 inch x 14 inch 2-bladed propellers. Fuel capacity was 64 imperial gallons (290 l). The craft were steered by twin rudders with steering wires that ran from the coxswain’s shelter aft through the well and engine compartment, and the last three foot (unarmoured) buoyancy section in the stern. The LCA propulsion system was designed to be quiet. At low speeds the engines could not be heard at 25 yards. The LCA handled well enough in moderate seas when waves were 3 to 5 ft (0.91 to 1.5 m) but could make no speed against rough weather, demonstrated in the number of LCA-hulled support craft that foundered in 6 ft (1.8 m) waves while on tow to Normandy (specifically LCA(HR)). The power-plant, while quiet, has been criticized for being underpowered. Nevertheless the bow lines and small ramp made the LCA a reasonably good sea boat.