World Wide Landing Ship Dock / Landing Platform Dock
Landing Ship Dock [LSD] and Landing Platform Dock [LPD] can ballast down in the water, thereby flooding the well deck with enough water to enable various sized landing craft to enter the well deck through the stern gate door. Once docked inside the well deck, troops, supplies and combat equipment can be loaded into or off of the amphibious boats and vehicles while simultaneously transporting troops and equipment via helicopter from the flight deck. The LPD has a helicopter platform built over a well deck in the rear of the vessel. This provides the tactical advantage of being able to lift troops, their combat equipment and supplies onto the same ship. Therefore, the ship contributes to all phases of the amphibious assault. The well deck are upper and lower vehicle storage areas, which hold most of the embarked troops' heavy combat equipment, such as tanks, tracked amphibious landing vehicles (AAV), jeeps and trucks. To facilitate the docking and loading of, the ship
Amphibious ship class taxonomies are not precise, have changed over time, and vary from country to country. Amphibious assault 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.
- LST - Landing Ship, Tank: Specialised type for getting tanks or other large vehicles ashore. Unlike other larger amphibious assault vessels, LSTs can beach and discharge directly onto shore.
- 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].
- Landing Ship Dock [LSD]: Perform the mission of amphibious transports and amphibious cargo ships. Unlike the LST, the LPD does not beach, and unlike the LPA the LPD loads landing craft in an interior well deck. Ships without a docking well must rely on transferring cargo to landing craft via deck-mounted cranes or stern ramps. The effectiveness of either method is heavily dependent on favorable conditions and are generally not feasible above Sea State 1 or 2.
- LPD - Amphibious Transport Dock: Perform the mission of amphibious transports, amphibious cargo ships and amphibious dock landing ships. The difference between a Landing Ship Dock [LSD] and a Landing Platform Dock [LPD] in the US Navy has changed over time. Initially the LPD had a helicopter landing deck, whereas the LSD did not. More recently, while the LSD has acquired a helicopter landing deck, it lacks the helicopter hangar found on the LPD. American LSDs typically carry 400-500 troops, while the LPDs carry 700-900 troops.
- LHD - Landing ship, Helicopter Dock: Multi-purpose amphibious assault ships that can deliver, elements of a landing force by air and amphibious craft. In the US Navy, LHDs have a displacement of over 40,000 tons and the latest LPD has a displacement of about 25,000 tons, though in other navies LPDs run as small as 8,000 tons. In general LHDs are larger than LPDs, though in principle the most obvious difference is that an LPD has a superstructure fore of the flight deck, while an LHD has a full length flight deck and a starboard island [like and aircraft carrier] - the ThyssenKrupp MHD-150 Enforcer series demonstrates the overlap between the two types.
- LHA- Landing ship, Helicopter Assault: General-purpose amphibious assault ships that serve both landing craft and helicopters, with a primary emphasis on aviation rather than landing craft.
- LPH - Landing Platform, Helicopter: Designed to support vertical envelopment helicopter assault, LPHs are similar to conventional aircraft carriers, with flight and hangar decks, though no ski jump or catapult for fixed wing aircraft. facilities. Unlike the LHA, an LPH has no well deck. LHA-6 America will be the first modern US Navy amphibious assault ship without a stern well deck, this being replaced by expanded aviation capabilities, and accordingly she should rather be designated as a LPH.
LSDs and LPDs are generally similar externally, though in the US Navy the LSDs are focused on cargo and LPDs on personnel. US Navy LPDs also carry the medical and staff components for when they split the Expeditionary Strike Group, with the LHA/LHD going in one direction and the LSD with LPD elsewhere. That split allows for detachments that would not be available if it was all big decks. LSD/LPD are also capable of getting into areas the LHA/LHDs are too big and have too deep of a draft.
Many middle-tier navies are reducing their focus on surface combatants and submarines, and improving their capability in naval expeditionary warfare. There is a major increase in the number of amphibious warfare ships entering service in navies big and small, east and west. Various types of amphibious ships are being studied, on order or under construction for navies which have not operated similar warships. LPDs are emerging as key military items for Southeast Asian countries for enhancing naval defense capabilities. The LPD is designed to transport troops into a war zone by sea using landing craft. It embarks, transports and lands soldiers and landing craft and can also be used for landings by helicopters. Even for a comparatively small navy an LPH or LHD makes a lot of sense because of the tremendous range of capabilities and options it can offer a defence force.
The trend toward expeditionary roles has particularly taken hold in Asia. Such expeditionary ships allow countries to play more significant and meaningful roles in joint coalition operations. Making the ships affordable is a major issue in any navy. One approach is to reduce the military requirements which can drive unit costs to over a billion dollars, as with the U.S. Navy's new San Antonio-class LPDs. Other countries can't afford to spend that kind of money on one ship, and so they design their amphibious ships to commercial standards, such as the Rotterdam. Multirole ships can be easier to sell to cash-strapped parliaments. Some navies believe it is a bit less militaristic to call it a vessel a "multipurpose support ship". Warships in some navies are becoming instruments of multinational diplomacy, conducting anti-piracy and disaster relief operations. But by whatever name, it is probably fair to conclude that any state which does not at least operate LSD or LPD types of ships does not have a meaningful amphibious capability.
