Liberty ship

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Missing image
SS John W. Brown is one of only two surviving Liberty ships.

SS John W. Brown, one of two surviving Liberty ships.
General Characteristics
Displacement: 7,000 tons deadweight
Length: 441 ft 6 in (135 m)
Beam: 56 ft 10.75 in (17.3 m)
Draft: 27 ft 9.25 in (8.5 m)
Propulsion: Two oil fired boilers,
triple expansion steam engine,
single screw, 2500 horsepower (1.9 MW)
Speed: 11 to 11.5 knots (20 to 21 km/h)
Complement: 41
Armament: Stern-mounted 4 in (102 mm) deck gun for use against surfaced submarines, variety of anti-aircraft guns.
Capacity: 9,140 tons cargo

The Liberty ships were cargo ships built in the United States during World War II. They were cheap and quick to build, and came to symbolize U.S. wartime industrial output. Based on vessels ordered by Great Britain to replace ships torpedoed by German U-boats, they were purchased for the U.S. fleet and for lend-lease provision to Britain. Sixteen American shipyards built 2,751 Liberties between 1941 and 1945, easily the largest number of ships produced to a single design.

The production of these vessels mirrored, at much larger scale, the manufacture of the Hog Island ship and similar standardized types during the First World War. The immense effort to build Liberty ships, the sheer number of ships built, and the fact that some of the ships survived far longer than the original design life of five years, make them the subject of much study.


History and service

In 1936, the American Merchant Marine Act was passed to subsidize the annual construction of 50 commercial merchant vessels to be used in wartime by the United States Navy as naval auxilaries. The number was doubled in 1939 and again in 1940 to 200 ships a year. Ship types included a tanker and three types of merchant vessel, all to be powered by steam turbines. But limited industrial capacity, especially for turbine construction, meant that relatively few of these ships were built.

In 1940, the British Government ordered 60 tramp steamships from American yards to replace war losses and boost the merchant fleet. This Ocean class were simple but fairly large (for the time) with a single coal-fired, 2,500-horsepower reciprocating engine of obsolete but reliable design. Britain specified coal plants because it had plenty of coal mines but no indigenous oil fields. The predecessor designs, including the Northeast Coast, Open Shelter Deck Steamer, were based on a simple ship originally produced in Sunderland by J.L. Thompson & Sons in 1879, and widely manufactured until the SS Dorrington Court of the 1930s. The order specified an 18-inch increase in draught to boost displacement by 800 tons to 10,100 tons. The accommodation, bridge and main engine of these vessels were located amidships, with a long tunnel to connect the main engine shaft to its aft extension to the propeller. The first Ocean-class ship, Ocean Vanguard was launched on 15 October 1941.

The design was modified by the United States Maritime Commission to conform to American construction practices and to make it even quicker and cheaper to build. The U.S. version was designated EC2-S-C1 — Emergency Cargo, 2 = large ship. The new design replaced much riveting, which accounted for one-third of the labour costs, with welding. The order was given to a conglomerate of West Coast engineering and construction companies known as the Six Companies, headed by Henry J. Kaiser, and also adopted as the Merchant Marine Act design.

On 27 March 1941, the number of lend-lease ships was increased to 200 by the Defense Aid Supplemental Appropriations Act, and increased again in April to 306, of which 117 would be Liberty ships.

The ships initially had a poor public image. To try to assuage public opinion, 27 September 1941 was designated Liberty Fleet Day, and the first 14 "Emergency" vessels were launched that day. The first of these was SS Patrick Henry, launched by President Franklin D. Roosevelt. In remarks at the launch ceremony, FDR cited Patrick Henry's 1775 speech that finished "Give me liberty or give me death". Roosevelt said that this new class of ships would bring liberty to Europe, which gave rise to the name Liberty Ship.

Early on, each ship took about 230 days to build (Patrick Henry took 244 days), but the average eventually dropped to 42 days. The record was set by Robert E. Peary, which was launched 4 days and 15 1/2 hours after the keel was laid, although this publicity stunt was not repeated. The ships were made assembly-line style, from prefabricated sections. In 1943, three new Liberty ships were being completed every day. They were mainly named after famous Americans, starting with the signatories of the Declaration of Independence.

Any group which raised War bonds worth $2 million could propose a name. Most were named for deceased people. The only living namesake was Francis J. O'Gara, the purser of the SS Jean Nicolet, who was thought to have been killed in a submarine attack but in fact survived the war in a Japanese prisoner of war camp. Other exceptions to the naming rule were the SS Stage Door Canteen, named for the USO club in New York, and the SS U.S.O., named after the organisation itself [1] (

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Another notable Liberty ship was SS Stephen Hopkins, which sank a German commerce raider in a ship-to-ship gun battle in 1942 and became the first American ship to sink a German surface combatant.

SS Richard Montgomery is also notable, though in a less positive way; the wreck of the ship lies off the coast of Kent with 1,500 tons of explosives still on board, enough to match a small nuclear weapon should they ever go off.

Many Liberty ships suffered hull and deck cracks, and some were lost to such structural defects. During WWII, there were nearly 1,500 serious brittle fractures. Nineteen ships broke in half without warning, including the SS John P. Gaines, which sank on 24 November 1943 with the loss of 10 lives. The ships were built in great haste, often by inexperienced people, in the era before embrittlement effects on steel were well understood; they were frequently grossly overloaded; and some of the problems occurred during or after severe storms at sea that would have placed any ship at risk. Still, the successor design, the Victory ship, was built stronger and less stiff.

Several designs of mass-produced petroleum tankers were also produced, the most numerous being the T2 tanker series, with about 490 built between 1942 and the end of 1945.

The last Liberty ship constructed was the SS Albert M. Boe, launched on 26 September 1945 and delivered on 30 October 1945. She was named after the chief engineer of a United States Army freighter who had stayed belowdecks to shut down his engines after a 13 April 1945 explosion, an act that won him a posthumous Merchant Marine Distinguished Service Medal [2] (

Many Liberty ships survived the war, and made up a large percentage of the postwar cargo fleet. The term "Liberty-size cargo" for 10,000 tons may still be heard in the shipping business. As of 2005, two Liberty ships survive: the SS John W. Brown and the Jeremiah O'Brien. Both museum ships, they still put out to sea regularly.


Liberty ships were built at 17 shipyards[3] (, including:

Fictional appearances

In David Gerrold's Star Wolf novels, liberty ships were destroyer-type warships designed to be cheaply mass-produced in an effort to rapidly beef up the human starfleets. The ships were assigned hull numbers (example: LS-1187), and were required to be victorious in space combat before they could take on an official name chosen by a majority vote of the ship's crew.

See also

External links



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