Landing Platform, Amphibious
Amphibious ship class taxonomies are not precise, have changed over time, and vary from country to country. Amphibious asault ships span a spectrum of capabilities, defined by the relative emphasis on helicopter aviation versus landing craft assets for transporting troops and equipment from sea to shore. They may also be defined by the presence or absence of a bow ramp by which vehicles may be directly discharged onto the beach [a Landing Ship, Tank - LST], or by a floodeable well dock by which smaller ampbibious craft [boats, etc] may be loaded and discharged directely into the water [ a Landing Ship, Dock - LSD, or Landing Platform, Dock].
During World War II, the Allies initially lacked large, purpose-designed landing craft (essential for the distances involved), but had lots of conventional freighter & passenger ships that had been "taken up from trade". Attack transports (Navy designation APA) and attack cargo ships (AKA), originally called combat loaders, were transports (troop carriers) and cargo ships modified to carry landing craft suitable for amphibious assaults. An APA could carry a battalion of troops. Three APAs and an AKA could carry a regiment. The "Attack Transports" (APA), were later redesignated "Amphibious Transports" (LPA) and "Attack Cargo Ships" (AKA, were later redesignated "Amphibious Cargo Ships" (LKA).
During World War II a number of American destroyer escorts [DE] undwerwent conversion to a high speed transport, and were reclassified APD. The missions of such APDs were varied, and included delivert of underwater demolition teams (UDT's) to destroy obstacles on landing beaches. These high-speed transports combined the hull of a warship, a destroyer escort, with the superstructure of a troop transport designed to both carry and launch amphibious landing forces. To accomplish this dual role, a substantial length of the main deck was enclosed to house 160 troops, while a cargo hold fitted with a crane capable of handling light vehicles and equipment was added further aft. In addition, the three-tube centerline torpedo station found on the destroyer escort class was removed to make room for port and starboard boat stations capable of launching and recovering four thirty-six-foot landing boats. To make room for these structural modifications, each high-speed transport featured only one 5-inch gun for its main armament, rather than the two such weapons found on a destroyer escort. During the Korean War four of these highly specialized ships provided the operational catalyst for the multinational raiding force that repeatedly struck North Korea's railway system.
Landing craft are craft especially designed for beaching, unloading, or loading on a beach, and retracting. This term generally is applied to nonocean-going vessels, less than 160 feet long, designed for use in landing operations; the designation landing craft (LC) is used with appropriate modifications to designate particular types. Landing craft were ramped vessels small enough to be carried aboard APAs, AKAs, or LSTs and included several types of 36-foot vessels designed to put troops and light vehicles on the beach and 56-foot landing craft, mechanized (LCM), originally intended to carry tanks. Some rubber boats were also designated as landing craft. Amphibious vehicles included landing vehicles, tracked (LVT), which were amphibious tractors; armored LVTs mounting howitzers; and amphibious trucks, of which the most important and numerous was the DUKW, or "Duck," an amphibious 2½-ton truck.
This solution worked, but there were problems in the second phase of operations. In order to load the landing craft quickly, the troops climbed down nets and/or rope ladders (and a few stair sets) to the craft beside the transport, which led to a large number of deaths & injuries due to falls into the ocean or the landing craft.
Several countries operate military vessels that are somewhat similar to an LSD or LPD, but lack the essential defining feature of this class, the floodable well dock.
- Argentina's single Hercules fast-attack transport was one of two Hercules class destroyers, ordered in 1970, to a design that is essentially the same as that of the Royal Navy's Type 42 Batch 1 (Sheffield) class. In 2000, Hercules was reactivated and transferred to the ASMAR Shipyard in Talcahuano, Chile for conversion to a "fast-attack transport". This entailed replacing the superstructure aft of the mainmast with a large hangar for a pair of Sea King helicopters, extending the flight deck, adding facilities for launching and recovering RHIBs.
- Australia's 2 L 51 Kanimbla-class Landing Platform, Amphibious [LPA] perform the mission of amphibious transport and, amphibious cargo ships. and amphibious dock landing ships. Unlike the LST, the LPA does not beach, but rather carries landing craft on the forward deck and can load cargo from a stern door [the stern is superficially similar in appearance to that of the LSD and LPD, but the deck does not flood].
- Denmark's 2 Absolon frigate Flexible Support Ship / Command Support Ship adds a large roll-on/roll-off deck to the standard frigate configuration, but it is not an LPD, since it lacks a floodable dock.
- New Zealand's 2 HMNZS Canterbury Multi-Role Vessel is based on a small ferry design, similar to an LPD type, but without a well dock. By one report New Zealand had 21 different shipyards offer different designs.
- Sweden's 2 L10 Combat Support Ships may follow New Zealand's modified ferry MRV solution instead of buying a more expensive amphibious ship. Sweden is typing their MRV as a combat support vessel. Sweden is planning to spend in the neighborhood of 60-70 million Euros for their L-10 MRV. The Swedish ship will be 140-145 meters in length. Sweden may buy and build modified Canterbury geared more as a tender than as a patrol ship with both ships having ro-ro ferry capabilities.
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