Liberty-class Merchant Vessel
|Launched||27 Sep 1941|
|Displacement||7176 tons standard; 14245 tons full|
|Machinery||Three-cylinder reciprocating steam engine, two oil boilers, one screw|
|Power Output||2500 SHP|
|Armament||1x4in or 1x5in stern gun, optional anti-aircraft weaponry such as 3in bow gun, 37mm bow guns, or 20mm machine guns|
|Cargo Capacity||9,140 tons|
Contributor: C. Peter Chen
This article refers to the entire Liberty-class; it is not about an individual vessel.
The Merchant Marine Act, passed by the United States Congress in 1936, established the United States Maritime Commission that supervised the construction of an US Merchant Marine fleet that served in the civilian capacity during peaceful times but could easily convert to military transport use in times of war. Federal subsidies for the construction and operation of Merchant Marine vessels were also established. The size of the Merchant Marine was 50 in 1936, but was increased to 200 by 1940. The high war time demand for steam turbines, however, limited the construction of these ships, thus limiting the result that the Merchant Marine Act was meant to achieve. In 1940, Britain ordered 60 Ocean-class tramp steamships from American civilian shipyards to replace war losses. The design was simple and easy to build, with a coal-burning powerplant. The first Ocean-class ship, Ocean Vanguard, was launched on 16 Aug 1941. Very soon, the design was modified to conform to American construction practices in order to increase production efficiency. Namely, riveting methods were changed to save significant labor costs. To further increase efficiency, a new method of construction was invented: the ships were to be built in modularized sections, and they would be put together by welding instead of rivets. The resulting ship looked unconventional, or even ugly by some standards; after seeing the design, Franklin Roosevelt commented that "I think this ship will do us very well", but also described her as a useful ship that was a "real ugly duckling." The first 14 of these ships, now categorized as the Liberty-class, launched according to schedule on 27 Sep 1941. That date was promptly celebrated as the Liberty Fleet Day. The first of the 14 Liberty Ships was SS Patrick Henry. Henry, the American Revolutionary War hero who famously declared "give me liberty, or give me death", was among the reasons for the name of the class.
In the earlier days of the construction, it took about 230 days to build a Liberty Ship. Already impressive, construction time was actually reduced to an average of 42 days. The record for Liberty Ship construction was held by the building of SS Robert E. Peary, which was launched 4 days, 15 hours, and 30 minutes after the keel was laid, although this record was by far the exception; much of the fitting-out work remained to be done after launching, and expectedly no other Liberty Ship came close to this record. By 1943, three Liberty Ships were being launched every day.
Between 1941 and 1945, the following 18 shipyards in the United States built Liberty Ships:
- Alabama Drydock and Shipbuilding, Mobile, Alabama
- Bethlehem-Fairfield Shipyard, Baltimore, Maryland
- California Shipbuilding Corp., Los Angeles, California
- Delta Shipbuilding Corp., New Orleans, Louisiana
- J. A. Jones, Panama City, Florida
- J. A. Jones, Brunswick, Georgia
- Kaiser Company, Vancouver, Washington
- Marinship, Sausalito, California
- New England Shipbuilding East Yard and West Yard, South Portland, Maine (subsidiaries of Bath Iron Works)
- North Carolina Shipbuilding Company, Wilmington, North Carolina
- Oregon Shipbuilding Corporation, Portland, Oregon
- Richmond Shipyards, Richmond, California (subsidiary of Kaiser Shipyards)
- St. Johns River Shipbuilding, Jacksonville, Florida
- Southeastern Shipbuilding, Savannah, Georgia
- Todd Houston Shipbuilding, Houston, Texas
- Walsh-Kaiser Co., Inc., Providence, Rhode Island
Early Liberty Ships suffered hull and deck cracks, some of which led to fatal sinkings; for example, on 24 Nov 1943, SS John P. Gaines broke in half and sank, taking 10 men with her. The blame originally was on the new welding method and the careless haste to build large quantities of ships, but Constance Tipper of Cambridge University in England, Britain found out that it was actually the cold temperatures of the North Atlantic that made the steel brittle, leading to cracking in some instances. Welding still had a role in it, however, as welding allowed small cracks to grow longer over time (something riveting would prevent), just that it was not the primary reason. Structural reinforcements were added to Liberty Ships later to remedy this problem.
Because Liberty Ships were deployed by the British before the Americans entered the war, and also because there were so many of them in use, there were many trivia items associated with them. For example, SS Stephen Hopkins was the first American ship to sink a German naval vessel, the merchant raider Stier.
While Liberty Ships symbolized wartime American industrial power, they also served the war in a practical sense: a single Liberty Ship could carry 2,840 jeeps, 440 tanks, or 230 million rounds of rifle ammunition. Each Liberty Ship was manned by a crew sized between 38 and 62; the crews were complimented by 21 to 40 US Navy personnel who operated the communications systems and weapons.
The last Liberty Ship built was SS Albert M. Boe, which was launched on 26 Sep 1945 and delivered on 30 Oct 1945. During the design's production life, 2,751 vessels were built; about 200 of them were lost during the war to various reasons. Many Liberty Ships remained in use in the United States, serving with the military during the Korean War as well as in civilian capacities. In the late-1960s, three Liberty Ships participated in US Navy radar research. As of 2005, two Liberty Ships remained operational; both museum ships, SS John W. Brown and SS Jeremiah O'Brien both sail regularly.
Sources: American Merchant Marine at War, United States National Park Service, Wikipedia.
Liberty-class Merchant Vessel Interactive Map
Liberty-class Merchant Vessel Operational Timeline
|27 Sep 1941||14 Liberty Ships were launched in the United States; they were to be transferred to the United Kingdom via the Lend-Lease program.|
|20 Sep 1942||As of this date, American Liberty ship production exceeded the rate of sinkings.|
|30 Oct 1945||Liberty Ship Albert M. Boe was delivered to the US Navy; she was to be the last Liberty Ship to be built.|
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James Forrestal, Secretary of the Navy, 23 Feb 1945