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.[1] The designation 'EC2-S-C1': 'EC' for Emergency Cargo, '2' for a ship between 400 and 450 ft (120 and 140 m) long (Load Waterline Length), 'S' for steam engines, and 'C1' for design C1.[2]
The class was named for the lead ship of its type, USS Crater (AK-70), 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 2,500 hp (1,864 kW) shaft.