Liberty ship

Liberty ships are a class of cargo ship that were built in the United States during World War II under the Emergency Shipbuilding Program. The idea for the ships came from Britain, but the United States used the design because it was simple and cheap to build. The ships were mass-produced in very large numbers. Because of this, Liberty ships became a symbol of American industry during the war.

The class was developed to meet British orders for transport ships to replace ships that had been sunk. Eighteen American shipyards built 2,710 Liberty ships between 1941 and 1945. This was an average of about three ships every two days. This was the largest number of ships ever built using one single design.

Later, the Liberty ship was replaced by the Victory ship. Victory ships were a little larger, much faster, and had more modern engines, but they were similar in design. A total of 531 Victory ships were built between 1944 and 1946.

History

Design

Profile plan of a Liberty ship

A colored diagram of compartments on a Liberty ship, from the right side, front to the right

  Machinery spaces

  Command and control

  Liquid stores

  Dry cargo

  Engine room

  Misc

  Dry stores

  Habitation

In 1936, the American Merchant Marine Act was passed. It helped pay for the building of 50 merchant ships each year. These ships could be used by the United States Navy during wartime as support ships. They were crewed by the U.S. Merchant Mariners. In 1939, the number was doubled. In 1940, it was increased again to 200 ships per year. The ship types included two tankers and three kinds of cargo ships. All of them were planned to use steam turbines. Because American industry could not make enough reduction gears, only a small number of these ships were actually built.

In 1940, the British government ordered 60 Ocean-class freighters from American shipyards. These ships were meant to replace ships lost in the war and to strengthen Britain’s merchant fleet. The ships were simple but large for their time. They used a single 2,500 horsepower (1,900 kW) compound steam engine. The engine design was old but very reliable. Britain asked for coal-fired engines because it had many coal mines but little oil production.

The earlier ship designs included the "Northeast Coast, Open Shelter Deck Steamer". These were based on a simple ship first built in Sunderland by J.L. Thompson & Sons. The design came from a 1939 tramp steamer that was cheap to build and operate (see Silver Line). One example was SS Dorington Court, built in 1939. The order required an 18-inch (0.46 m) deeper draft to increase carrying capacity by 800 long tons (810 t), for a total of 10,100 long tons (10,300 t). Crew spaces, the bridge, and the main engine were placed in the middle of the ship. A tunnel connected the engine to the propeller at the back. The first Ocean-class ship, SS Ocean Vanguard, was launched on 16 August 1941.

140-ton vertical triple expansion steam engine of the type used to power World War II Liberty ships, assembled for testing before delivery

The design was later changed by the United States Maritime Commission. This was done partly to match American building methods, but mainly to make the ships faster and cheaper to build. The American version was named “EC2-S-C1”. “EC” meant Emergency Cargo, “2” meant the ship was between 400 and 450 feet (120 and 140 m) long, “S” meant steam-powered, and “C1” was the design number. The new design replaced much of the riveting with welding, which greatly reduced labor costs. Oil-fired boilers were also used. The design was approved under the Merchant Marine Act, and construction was given to a group of West Coast companies led by Henry J. Kaiser. This group was known as the Six Companies. Liberty ships were designed to carry 10,000 long tons (10,200 t) of cargo, usually one type per ship. During the war, they often carried more than this amount.

On 27 March 1941, the number of lend-lease ships was increased to 200 by the Defense Aid Supplemental Appropriations Act. In April, the number was raised again to 306 ships. Of these, 117 were Liberty ships.

Sources

• Davies, James (2004). "Liberty Cargo Ship" (PDF). ww2ships.com. p. 23. Retrieved 25 March 2008.
• Elphick, Peter (2006). Liberty: The Ships that Won the War. Naval Institute Press. ISBN 1591144515.
• Herman, Arthur (2012). Freedom's Forge: How American Business Produced Victory in World War II. New York: Random House. ISBN 978-1400069644.
• Sawyer, L. A.; Mitchell, W. H. (1985). The Liberty Ships: The history of the "emergency" type cargo ships constructed in the United States during the Second World War. London: Lloyd's of London Press. ISBN 978-1850440499.
• Wise, James E.; Baron, Scott (2004). Soldiers Lost at Sea: A Chronicle of Troopship Disasters (2004 ed.). United States Naval Institute. ISBN 978-1591149668. Total pages: 280

Further reading

• Lane, Frederic Chapin (2001) [1951]. Ships for Victory: A History of Shipbuilding under the U.S. Maritime Commission in World War II. Baltimore: Johns Hopkins University Press. ISBN 978-0801867521. OCLC 45799004.
• Chiles, James R "The Ships That Broke Hilter's Blockade: How a crash effort by amateur shipbuilders turned out twenty-seven hundred Liberty freighters in four years" Winter 1988, Volume 3, Issue 3. Invention and Technology Magazine at American Heritage
• Lee, Bill "The Liberty Ships of World War II" An informative 30-page article about the ships, how they were built, and how they were used.

Other websites

• youtube How A Cargo Ship Helped Win WW2: The Liberty Ship Story
• SS Jeremiah O'Brien, Liberty museum ship moored at Fisherman's Wharf, San Francisco, California
• Liberty Ships built by the United States Maritime Commission in World War II Archived 9 May 2008 at the Wayback Machine
• Liberty Ships and Victory Ships, America's Lifeline in War Archived 11 June 2007 at the Wayback Machine A lesson on Liberty ships and Victory ships from the National Park Service's Teaching with Historic Places.
• Ships for Victory: J.A. Jones Construction Company and Liberty Ships in Brunswick, Georgia Archived 2008-06-09 at the Wayback Machine Eighty-four black-and-white photographs from the J.A. Jones Construction Company collection at the Brunswick-Glynn County Library that depict the company's World War II cargo ship building activities in its Brunswick, Georgia shipyard from 1943 to 1945.
• Project Liberty Ship – The Shipyards. Archived 31 May 2008 at the Wayback Machine
• Summary of Constance Tipper's work – contains remarkable photo of fractured Liberty ship still afloat.
• Danger presented by the wreck of liberty ship SS Richard Montgomery.
• Shipbuilding under the United States Maritime Commission, 1936 to 1950
• Liberty Ships and World War II – A Role Model
• The Last Liberty Ship: Kaiser (video)
• Brunswick's "Liberty Ships" historical marker