Repair ship

A repair ship is a naval auxiliary ship designed to provide maintenance support to warships. Repair ships provide similar services to destroyer, submarine and seaplane tenders or depot ships, but may offer a broader range of repair capability including equipment and personnel for repair of more significant machinery failures or battle damage.

United States Navy
The United States Navy became aware of the need for repair ships to maintain Asiatic Fleet ships stationed in the Philippines. Two colliers were converted to USS Prometheus (AR-3) and USS Vestal (AR-4) in 1913 before the purpose-built USS Medusa (AR-1) was completed at the Puget Sound Navy Yard in 1923. The following ships were converted to repair ships to meet the needs of World War II:
 * USS Vulcan (AR-5)
 * USS Ajax (AR-6)
 * USS Hector (AR-7)
 * USS Jason (AR-8)
 * USS Delta (AR-9)
 * USS Alcor (AR-10)
 * USS Rigel (AR-11)
 * USS Briareus (AR-12)
 * USS Amphion (AR-13)
 * USS Cadmus (AR-14)

United Kingdom
HMS Resource (F79) was built in 1928 and remained the sole Royal Navy repair ship at the outbreak of World War II. The following ships were converted to meet wartime needs:
 * HMS Adventure (M23)
 * HMS Alaunia (F15)
 * HMAS Albatross (1928)
 * HMS Artifex (F28)
 * RMS Ausonia
 * HMS Deer Sound
 * HMS Kelantan (F166)
 * SS Ranpura
 * HMS Vindictive (1918)
 * HMS Wayland (F137)
 * HMS Westernland (F87)

Lend/Lease
These Xanthus-class repair ships were built to Royal Navy specifications by Bethlehem Fairfield Shipyard in 1944, but only the first two were temporarily loaned to the United Kingdom while the others were retained for use by the United States Navy:
 * AR-17 became HMS Assistance (F173)
 * AR-18 became HMS Diligence (F174)
 * USS Xanthus (AR-19) was intended to be HMS Hecla (F175)
 * USS Laertes (AR-20) was intended to be HMS Dutiful (F176)
 * USS Dionysus (AR-21) was intended to be HMS Faithful (F177)

Japan
Japan found repair ships valuable for Pacific island bases. The pre-dreadnought battleship Asahi was modified and recommissioned as a repair ship in 1938. The 9,000-ton purpose-designed repair ship Akashi was launched in 1938 as the intended prototype for a class of five ships, but the remaining four ships were cancelled as other wartime shipbuilding projects assumed higher priority.