The LSD (U.S. Navyhull classification for landing ship, dock) came as a result of a British requirement during the Second World War for a vessel that could carry large landing craft across the seas at speed. The predecessor of all modern LSDs is Shinshū Maru of the Imperial Japanese Army, which could launch her infantry landing craft using an internal rail system and a stern ramp. She entered service in 1935 and saw combat in China and during the initial phase of Japanese offenses during 1942.
The first LSD of the Royal Navy came from a design by Sir Roland Baker who had designed the British landing craft tank. It was an answer to the problem of launching small craft rapidly. The landing ship stern chute, which was a converted train ferry (Train Ferry No. 1 which had been built for British Army use in the First World War), was an early attempt. Thirteen landing craft mechanized (LCM) could be launched from these ships down the chute. The landing ship gantry was a converted tanker with a crane to transfer its cargo of landing craft from deck to sea—15 LCM in a little over half an hour.[3]
The design was developed and built in the U.S. for the U.S. Navy and the Royal Navy. The LSD could carry 36 LCM at 16 knots (30km/h). It took one and a half hours for the dock to be flooded down and two and half to pump it out. When flooded they could also be used as docks for repairs to small craft. Smaller landing craft could be carried in the hold as could full-tracked and wheeled amphibious assault or support vehicles.
In the U.S. Navy, two related groups of vessels classified as LSDs are in service as of 2023, the Whidbey Island and Harpers Ferry classes, mainly used to carry hovercraft (LCACs), operate helicopters, and carry Marines.[4]
Ex-USS Hermitage (LSD-34) loaned in 1989 and later sold to Brazilian Navy, sunk as target 2021; ex-USS Alamo (LSD-33) loaned to Brazilian Navy in 1990, scrapped 2015 Turkey.
Ex-USS Alamo (LSD-33) loaned to Brazilian Navy; ex-USS Hermitage (LSD-34) loaned and later sold to Brazilian Navy; all other scrapped or sunk as target