The Type C4-class ship were the largest cargo ships built by the United States Maritime Commission (MARCOM) during World War II. The design was originally developed for the American-Hawaiian Lines in 1941, but in late 1941 the plans were taken over by the MARCOM. Eighty-one ships were built as cargo or troopships in four shipyards: Kaiser Richmond, California (35 ships), Kaiser Vancouver, Washington (20 ships), Sun Shipbuilding and Drydock in Chester, Pennsylvania (20 ships) and Bethlehem Steel Sparrows Point, Maryland (6 ships). All ships were capable of 17 kn, driven by a single screw steam turbine generating 9,900 shp. Among the variations of the design were the Haven-class hospital ship. They were followed post-war by thirty-seven of the larger C4-S-1 class, also known as the Mariner class.

List of Type C4 ships

General series

C4-S-A1 DWT: 14,863. Built by Kaiser Shipyards at Permanente No. 3 in Richmond, California, for the US Army Transportation Corps then transferred later to the US Navy. The 30 ships were built from 1942 to 1945. Sun Shipbuilding of Chester, Pennsylvania, originally had a contract to build 30 of the C4 ships. The USMC prioritized Sun's expertise in building urgently needed T2-SE-A1 tankers and withdrew 20 C4s from Sun and assigned them to Kaiser's Richmond, California yard. Kaiser's C4 troop ship construction became Navy troop ships ("General" names), Sun's became WSA troopships operated by commercial agents. In the 1960 the Navy sold off most of the General ships to private companies. Most were scrapped in the 1980s.

Marine series

C4-S-B1, C4-S-B2, C4-S-B5 ships built for troop and cargo transport. Marine series C4 ships were operated by the War Shipping Administration (WSA) through commercial companies acting as agents during World War II. Others became Navy hospital ships. Sun Shipbuilding of Chester, Pennsylvania, originally had a contract to build 30 of the C4 ships. The USMC prioritized Sun's expertise in building urgently needed T2-SE-A1 tankers and withdrew 20 C4s from Sun and assigned them to Kaiser's Richmond, California yard. Kaiser's C4 troop ship construction became Navy troop ships ("General" names), Sun's became WSA troopships operated by commercial agents.

C4-S-B1 (Sun)

Only one in class, built by Sun Yards of Chester, Pennsylvania.

C4-S-B2 (Sun)

14 built by Sun Ship for World War II were used as troop ships in 1944 and 1945. The United States Navy took over 6 to become Haven-class hospital ships in May 1945 and painted them white. Along with military troop movement, the C4-S-B2 participated in Operation Magic Carpet to bring home troops and their families. After the war others were converted to cargo ships.

C4-S-B2 (Todd)

Buit by Todd Brooklyn:

C4-S-B5 (Sun)

Built by Sun Ships in 1945.

C4-S-A3 (Kaiser)

ships built by Kaiser Shipyards in Richmond, California, in 1945 and 1946, as WSA troopship.

C4-S-A4 (Kaiser)

ships built by Kaiser Shipyards in Richmond, California, in 1946 for break bulk cargo

Mount series

C4-S-A3 as break bulk cargo ship.

Named after a person

C4-S-A3 as a break bulk ship in 1946.

Hospital ships

C4-S-B2 DWT: 15,300

M-class ships

** C4-S-49a** Four cargo/passenger liners were built for the Grace Line 1963–1964 by Bethlehem Steel Sparrows Point, Maryland.

Jet-class ships

C4-S-49b

Mariner-class ships

Mariner-class break bulk ships were 564 ft long with a capacity of. They have speed of 20 kn. They were some of the largest and fastest ships in the world when they were completed. Built between 1952 and 1955. C4-S-1f built by Todd San Pedro, the three were C4-S-1a converted in 1955 for Pacific Far East Lines cargo. C4-S-1h Conversion for break bulk ships for American President Lines in 1955. C4-S-1t

Mail ships

C4-S-1s received new 105 ft midbodies at Bethlehem Steel's San Francisco yard, this increasing their length from 564 ft to 669 ft. New bow thrusters were also installed. Operator American Mail Line. . Built in 1962.

State ships

C4-S-1u

African ships

Built by Ingalls Shipbuilders for Farrell Lines. . C4-S-58a

Moon ship

Built by Newport News for United States Lines in 1961. . C4-S-57a

American ships

Built by Newport News for States SS Company in 1959. , 529 ft length at the waterline, 18,150 shp, 22 kn top speed. Built by Sun Ship for United States Lines in 1964 and 1965. . Built by Beth Quincy for United States Lines in 1962 and 1963. .

Ro-Ro ships

Built by for the USN in 1967. One roll-on/roll-off ship in class C4-ST-67a

Notable incidents

Notes and citations