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
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  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  deeper draft to increase carrying capacity by , for a total of . 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.

 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  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  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.

## References
## Sources
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*   Total pages: 280 

## Further reading
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* 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 
* Liberty Ships and Victory Ships, America's Lifeline in War  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  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. 
* Summary of Constance Tipper's workcontains remarkable photo of fractured Liberty ship still afloat.
* Danger presented by the wreck of liberty ship .
* 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