The Crater-class cargo ship were converted EC2-S-C1 type, Liberty cargo ships, constructed by the United States Maritime Commission (USMC) for use by the US Navy during World War II. The designation 'EC2-S-C1': 'EC' for Emergency Cargo, '2' for a ship between long (Load Waterline Length), 'S' for steam engines, and 'C1' for design C1. The class was named for the lead ship of its type, , with most ships in the class being named for astronomical bodies. Its 65 hulls were among the largest US Navy cargo ship classes. The ships were propelled by a reciprocating steam engine using a single screw with a power of shaft. Notable incidents USS Aludra (AK-72) Lost in action from Japanese torpedo on 23 June 1943 south of Makira island. USS Deimos (AK-78) Damaged by torpedo, 23 June 1943, then abandoned and scuttled south of Makira island. References External links AK — Cargo Ships—Ships of the U.S. Navy, 1940–1945. Auxiliary ship classes of the United States Navy Crater class cargo ship