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Liberty ship

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Title: Liberty ship  
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Liberty ship

SS John W. Brown is one of only two surviving operational Liberty ships.
SS John W. Brown, one of two surviving operational Liberty ships, photographed in 2000
Class overview
Name: Liberty ship
Builders: 18 shipyards in the USA
Cost: US$2 million ($34 million in 2016)[1]
Planned: 2,751
Completed: 2,710
Preserved: 2
General characteristics
Class & type: Cargo ship
Displacement: 14,245 long tons (14,474 t)[2]
Length: 441 ft 6 in (134.57 m)
Beam: 56 ft 10.75 in (17.3 m)
Draft: 27 ft 9.25 in (8.5 m)
  • Two oil-fired boilers
  • triple-expansion steam engine
  • single screw, 2,500 hp (1,900 kW)
Speed: 11–11.5 knots (20.4–21.3 km/h; 12.7–13.2 mph)
Range: 20,000 nmi (37,000 km; 23,000 mi)
Capacity: 10,856 t (10,685 long tons) deadweight (DWT)[2]
Armament: Stern-mounted 4-in (102 mm) deck gun for use against surfaced submarines, variety of anti-aircraft guns

The Liberty ship was a ship class of cargo ship built in the United States during World War II. Though British in conception, the design was adapted by the U.S. for its simple, low-cost construction.[4] Mass produced on an unprecedented scale, the now iconic Liberty ship came to symbolize U.S. wartime industrial output.

The class was developed to meet British orders for transports to replace those torpedoed by German U-boats. The vessels were purchased both for the U.S. fleet and lend-lease deliveries of war materiel to Britain and the Soviet Union. Eighteen American shipyards built 2,710 Liberty ships between 1941 and 1945, easily the largest number of ships produced to a single design.

Their production mirrored on a much larger scale the manufacture of the Hog Islander and similar standardized ship types during World War I. The immensity of the effort, the sheer number of ships built, the vaunted role of Rosie the Riveters in their construction, and the survival of some far longer than their original five-year design life, all make them the subject of much continued interest.

Only a handful remain in 2015, two as operational museum ships.


  • History and service 1
    • Design 1.1
    • Propulsion 1.2
    • Construction 1.3
    • Problems 1.4
      • Hull cracks 1.4.1
    • Use as troop ships 1.5
    • After the war 1.6
  • Shipyards 2
  • Ships in class 3
  • In popular culture 4
  • See also 5
  • References 6
  • Further reading 7
  • External links 8

History and service

Profile plan of a Liberty ship


In 1936, the American Merchant Marine Act was passed to subsidize the annual construction of 50 commercial merchant vessels which could be used in wartime by the United States Navy as naval auxiliaries. 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. Limited industrial capacity, especially for reduction gears, meant that relatively few of these ships were built.

In 1940 the British government ordered 60 Ocean-class freighters from American yards to replace war losses and boost the merchant fleet. These were simple but fairly large (for the time) with a single 2,500 hp (1,860 kW) reciprocating steam engine of obsolete but reliable design. Britain specified coal-fired plants because it had extensive coal mines but did not at the time have significant domestic oil fields, as the major North Sea field had yet to be discovered.

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

The predecessor designs, which included the Northeast Coast, Open Shelter Deck Steamer, were based on a simple ship originally produced in Sunderland by J.L. Thompson & Sons (see Silver Line) from 1879, and widely manufactured up to the SS Dorington Court built in 1939.[5] The order specified an 18-inch (0.5 m) increase in draft to boost displacement by 800 long tons (810 t) to 10,100 long tons (10,300 t). The accommodation, bridge, and main engine were located amidships, with a tunnel connecting the main engine shaft to the propeller via a long aft extension. The first Ocean-class ship, SS Ocean Vanguard, was launched on 16 August 1941.

The design was modified by the United States Maritime Commission, in part to increase conformity to American construction practices, but more importantly to make it even quicker and cheaper to build. The US version was designated 'EC2-S-C1': 'EC' for Emergency Cargo, '2' for a ship between 400 and 450 feet (120 and 140 m) long (Load Waterline Length), 'S' for steam engines, and 'C1' for design C1. The new design replaced much riveting, which accounted for one-third of the labor costs, with welding, and had oil-fired boilers. It was adopted as a Merchant Marine Act design, and production awarded to a conglomerate of West Coast engineering and construction companies headed by Henry J. Kaiser known as the Six Companies. Liberty ships were designed to carry 10,000 tons of cargo, usually one type per ship, but, during wartime, generally carried loads far exceeding this.[6]

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.


By 1941, the steam turbine was the preferred marine steam engine because of its greater efficiency compared to earlier reciprocating compound steam engines. Steam turbine engines required very precise manufacturing techniques and balancing and a complicated reduction gear, however, and the companies capable of manufacturing them already were committed to the large construction program for warships. Therefore a 140-ton[7] vertical triple expansion compound steam engine of obsolete design was selected to power Liberty ships because it was cheaper and easier to build in the numbers required for the Liberty ship program and because more companies could manufacture it. Eighteen different companies eventually built the engine. It had the additional advantage of ruggedness and simplicity. Parts manufactured by one company were interchangeable with those made by another, and the openness of its design made most of its moving parts easy to see, access, and oil. The engine – 21 feet (6.4 meters) long and 19 feet (5.8 meters) tall – was designed to operate at 76 rpm and propel a Liberty ship at about 11 knots (12.7 mph; 20.4 km/hr).[8]


The ships were constructed of sections that were welded together. This is similar to the technique used by Palmer's at Jarrow, northeast England, but substitutes welding for riveting. Riveted ships took several months to construct. The work force was newly trained – no one had previously built welded ships. As America entered the war the shipbuilding yards employed women, to replace men who were enlisting in the armed forces.[9]

The ships initially had a poor public image due to their appearance. In a speech announcing the emergency shipbuilding program President Franklin D. Roosevelt had referred to the ship as "a dreadful looking object", and Time magazine called it an "Ugly Duckling". September 27, 1941, was dubbed Liberty Fleet Day to try to assuage public opinion, as the first 14 "Emergency" vessels were launched that day. The first of these was SS Patrick Henry, launched by President 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.

Aerial photograph of the Liberty ship SS John W. Brown outbound from the United States carrying a large deck cargo after her conversion to a "Limited Capacity Troopship." It probably was taken in the summer of 1943 during her second voyage.

The first ships required about 230 days to build (Patrick Henry took 244 days), but the average eventually dropped to 42 days. The record was set by SS Robert E. Peary, which was launched 4 days and 15½ hours after the keel was laid, although this publicity stunt was not repeated: in fact much fitting-out and other work remained to be done after the Peary was launched. The ships were made assembly-line style, from prefabricated sections. In 1943, three Liberty ships were completed daily. They were usually named after famous Americans, starting with the signatories of the Declaration of Independence.

Any group which raised

  • [11] SS Jeremiah O'Brien
  • 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 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)[12]

External links

  • Davies, James (2004). "Liberty Cargo Ship" (PDF). p. 23. Retrieved 25 March 2008. 
  • Elphick, Peter. Liberty: The Ships that Won the War. Naval Institute Press, 2006. ISBN 1-59114-451-5
  • Sawyer, L. A.; W. H. Mitchell (1970). The Liberty Ships: The history of the "emergency" type cargo ships constructed in the United States during World War II. Cambridge, Maryland: Cornell Maritime Press.  
  • Chiles, James R . "THE SHIPS THAT BROKE HITLER’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
  • Herman, Arthur (2012). Freedom's Forge: How American Business Produced Victory in World War II. New York, NY: Random House.  
  • 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.
  • Wise, James E.; Baron, Scott (2004). Soldiers Lost at Sea: A Chronicle of Troopship Disasters (2004 ed.). - Total pages: 280  

Further reading

  1. ^ Wise & Baron 2004, p. 140
  2. ^ a b Davies, 2004, page 23.
  3. ^ "Liberty Ships Design". 2012. Retrieved 7 May 2012. 
  4. ^ Video: America Reports On Aid To Allies Etc. (1942).  
  5. ^ [7]
  6. ^ [8]- cite: American Merchant Marine at War; retrieved 2012-07-20
  7. ^ Live (the program of Project Liberty Ship provided for cruises of the Liberty ship SS John W. Brown, 2013 edition, claims both that the engine weighed 135 tons (p. 10) fully assembled and that it weighed 140 tons (p. 11).
  8. ^ Live (program of Project Liberty Ship provided for cruises of the Liberty ship SS John W. Brown, 2013 edition, p. 10.
  9. ^ Herman, Arthur. Freedom's Forge: How American Business Produced Victory in World War II, pp. 135-6, 178-80, Random House, New York, NY, 2012. ISBN 978-1-4000-6964-4.
  10. ^ Reading 1: Liberty Ships National Park Service Cultural Resources.
  11. ^ [9]
  12. ^ The Hoverfly in CBI, Carl Warren Weidenburner
  13. ^ "Albert M. Boe"SS . 2004. Retrieved 7 May 2012. 
  14. ^ "Liberty Ships - B". Mariners. Retrieved 6 January 2012. 
  15. ^ "Liberty Ships - N - O". Mariners. Retrieved 6 January 2012. 
  16. ^ Wreck of the SS John P Gaines
  17. ^ Fracture – some maritime examples. Mechanical Engineering Department, University of Western Australia.
  18. ^ a b Constance Tipper (researcher into Liberty ship fracture)
  19. ^ Hedley-Whyte, John; Milamed, Debra R. "Asbestos and Ship-Building: Fatal Consequences". Ulster Medical Journal (Ulster Medical Society) (September 2008): 191–200.  
  20. ^ a b c d e f g Wardlow, Chester (1956). The Technical Services—The Transportation Corps: Movements, Training, And Supply. United States Army In World War II. Washington, DC: Center Of Military History, United States Army. pp. 145–148.  
  21. ^ Masterson, Dr. James R. (1949). U. S. Army Transportation In The Southwest Pacific Area 1941-1947. Washington, D. C.: Transportation Unit, Historical Division, Special Staff, U. S. Army. pp. 570–571. 
  22. ^ Bykofsky, Joseph; Larson, Harold (1990). The Technical Services—The Transportation Corps: Operations Overseas. United States Army In World War II. Washington, DC: Center Of Military History, United States Army. p. 450.  
  23. ^ a b Wardlow, Chester (1999). The Technical Services—The Transportation Corps: Responsibilities, Organization, And Operations. United States Army In World War II. Washington, DC: Center Of Military History, United States Army. pp. 300–301.  
  24. ^ The Shipping World and Shipbuilding & Marine Engineering News, 1952, p. 148.
  25. ^ a b c Elphick, Peter. , p. 401.Liberty
  26. ^ Elphick, Liberty, p. 309.
  27. ^ Elphick, Liberty, p. 166.
  28. ^ Elphick, Liberty, p. 271.
  29. ^ Elphick, Liberty, p. 108.
  30. ^ Elphick, Liberty, p. 402.
  31. ^ Elphick, Liberty, p. 325.
  32. ^ Maritime Administration. "Samuel R. Aitken". Ship History Database. U.S. Department of Transportation, Maritime Administration. Retrieved 1 November 2014. 
  33. ^ Maritime Administration Vessel Status Card. "Robert W. Hart". Ship History Database. U.S. Department of Transportation, Maritime Administration. Retrieved 1 November 2014. 
  34. ^ Maritime Administration Vessel Status Card. "J. Howland Gardner". Ship History Database. U.S. Department of Transportation, Maritime Administration. Retrieved 1 November 2014. 
  35. ^ Maritime Administration Vessel Status Card. "Iran Victory". Ship History Database. U.S. Department of Transportation, Maritime Administration. Retrieved 1 November 2014. 
  36. ^ Maritime Administration Vessel Status Card. "Simmons Victory". Ship History Database. U.S. Department of Transportation, Maritime Administration. Retrieved 1 November 2014. 
  37. ^
  38. ^ The Hudson River National Defense Reserve Fleet [10] "The fleet was at its peak with 189 ships in July of 1965."
  39. ^ Image: Mothball Fleet of WWII Liberty Ships in Hudson River off Jones Point 1957 Picture of mothballed liberty ships
  40. ^ Walker, Ashley (Historic American Engineering Record) (2009). "Operation "Pluto" - Arthur M. Huddell, James River Reserve Fleet, Newport News, Newport News, VA". Library of Congress Prints and Photographs Division Washington, D.C. 20540. Retrieved 5 October 2014. 
  41. ^ The Hellas Liberty Project
  42. ^ Did You Know: Liberty Ships Still Afloat in Portland
  43. ^ Adams, Rod (November 1, 1995). "Army Nuclear Power Plants". Retrieved 7 May 2012. 
  44. ^ a b "The Calendar of Modern Shipping". ca. February 26, 2010. Archived from the original on February 26, 2010. Retrieved June 9, 2014. 
  45. ^ Proceedings of the Merchant Marine Council Vol 12 No 5 May 1955 pg 85
  46. ^ Specht D. Evaluation of free piston-gas turbine marine propulsion machinery in GTS William Patterson (1961) SAE
  47. ^ Proceedings of the Merchant Marine Council Vol 14 No 11 Nov 1957 pg 183
  48. ^ National Research Council (U.S.) Innovation in the Maritime Industry (1979) Maritime Transportation Research Board pp.127-131
  49. ^ "Postal Service Salutes U.S. Merchant Marine on Forever Stamps". Press Release. USPS. 28 July 2011. Retrieved 25 May 2012. 
  50. ^ "WWII Construction Records, Private-Sector Shipyards that Built Ships for the U.S. Maritime Commission". Colton Company. Archived from the original on 13 November 2007. Retrieved 1 December 2007. 
  51. ^ "McCloskey & Co., Hookers Point, Tampa, Florida, U.S.A."
  52. ^ "Builders of Concrete Ships: WWII Construction Record"


See also

  • The fictional USS Reluctant (AK-601) of Thomas Heggen's novel and the TV series Mister Roberts was a Liberty ship. The ship used in the 1955 movie was a Camano-class light freighter that served in World War II and the Korean War.
  • The 3 May 1942 episode of the radio comedy The Great Gildersleeve revolves around a trip to the Richmond Shipyards where Gildersleeve's niece Marjorie christens a Liberty Ship the Throckmorton P. Gildersleeve.
  • The wreck of the SS Richard Montgomery is central to the plot of Stephen Barlay's 1977 novel Blockbuster, in which an extortionist threatens to blow it up, thereby causing serious flooding in central London, if his demands are not met.
  • Most of the engine room scenes of the 1997 film Titanic were shot aboard the museum Liberty Ship SS Jeremiah O'Brien in San Francisco Bay. Scott Sigler's book Nocturnal also has several scenes that take place on the Jeremiah O'Brien.
  • A Liberty ship is featured in the Humphrey Bogart 1943 film Action in the North Atlantic. Its deck gun is described as being 5" rather than 4", probably for wartime propaganda reasons. Called the Seawitch in the film, its dedication plaque describes it as "Built for/ U.S. Maritime Commission/ Hull No. 628B/ by/ Atlas Shipbuilding Corporation/ Kearny, New Jersey/ April 1943".
  • A Liberty ship, converted to a hospital ship, is the subject and setting of Alistair MacLean's mystery thriller San Andreas (1984) The prologue to this novel, also by MacLean, is an essay on Liberty ships and the conditions, character and behavior of the British Merchant Marine owners that used them, and sailors that sailed them.

In popular culture

Ships in class

Liberty ships were built at eighteen shipyards located along the U.S. Atlantic, Pacific and Gulf coasts:[50]


In 2011, the United States Postal Service issued a postage stamp featuring the Liberty ship as part of a set on the U.S. Merchant Marine.[49]

In the 1950s, the Maritime Administration instituted the Liberty Ship Conversion and Engine Improvement Program, which had a goal to increase the speed of Liberty ships to 15 knots, making them competitive with more modern designs, as well as gaining experience with alternate propulsion systems. Four ships were converted in the $11 million program.[45] The SS Benjamin Chew had its existing condensers modified and a new superheater and geared turbine installed to give the ship 6,000 shp, up from 2,500. The SS Thomas Nelson had its bow lengthened, diesel engines installed in place of the original steam engine, and movable cranes outfitted in place of the original cargo handling gear. The GTS(Gas Turbine Ship) John Sergeant had its bow extended, and its steam engine replaced with a General Electric gas turbine of 6,600 shp, connected to a reversible pitch propeller via reduction gearing. John Sergeant was considered overall to be a success, but problems with the reversible pitch propeller ended its trial after 3 years. The GTS William Patterson had its bow extended and its steam engine replaced with 6 General Electric GE-14 free-piston gas generators, connected to two reversible turbines and capable of 6,000 shp total. William Patterson was considered to be a failure as reliability was poor and the scalability of the design was poor.[46][47] All four vessels were fueled with Bunker C fuel oil, though John Sergeant required a quality of fuel available at limited ports and also required further treatment to reduce contaminants.[48] Three were scrapped in 1971 or 1972 and the diesel-equipped Thomas Nelson was scrapped in 1981.

Fifty-eight Liberty ships were lengthened by 70 feet (21 m) starting in 1958.[44] This gave the ships an additional 640 long tons (650 t) of carrying capacity at a small additional cost.[44] The bridges of most of these were also enclosed in the mid-1960s in accordance with a design by naval architect Ion Livas.

SS Charles H. Cugle was converted into MH-1A (otherwise known as USS Sturgis). MH-1A was a floating nuclear power plant and the first ever built. MH-1A was used to generate electricity at the Panama Canal Zone from 1968–1975. She was also used as a fresh water generating plant. She is anchored in the James River Reserve Fleet.[43]

Liberty ships continue to serve in a "less than whole" function many decades after their launching. In Portland, Oregon, the hulls of Richard Henry Dana and Jane Addams serve as the basis of floating docks.[42] SS Albert M. Boe survives as the Star of Kodiak, a landlocked cannery, in Kodiak Harbor at .

Only two operational Liberty ships, SS John W. Brown and SS Jeremiah O'Brien, remain. Brown has had a long career as a school ship and many internal modifications, while O'Brien remains largely in her original condition. Both are museum ships that still put out to sea regularly. In 1994, O'Brien steamed from San Francisco to England and France for the 50th anniversary of D-Day, the only large ship from the original Overlord fleet to participate in the anniversary. In 2008, SS Arthur M. Huddell, a ship converted in 1944 into a pipe transport to support Operation Pluto,[40] was transferred to Greece and converted to a floating museum dedicated to the history of the Greek merchant marine;[41] although missing major components were restored this ship is no longer operational.

SS Hellas Liberty (ex-SS Arthur M. Huddell) in June 2010

In 1965, 189 liberty ships were mothballed on the Hudson River near Tarrytown. This was the highest number stored there.[38][39]

Liberty Ships in mothballs at Tongue Point, Astoria, Oregon
Liberty Ships in mothballs at Tongue Point, Astoria, Oregon

From 1946 to 1963, the U.S. Navy stored mothballed Liberty ships at Tongue Point Naval Air Station. Known as the Pacific Ready Reserve Fleet - Columbia River Group, as many as 500 ships were stored there.[37]

In the 1960s, three Liberty ships and two Victory ships were reactivated and converted to  (AGTR-3)JamestownUSS  with the Victory ships being SS Iran Victory which became USS Belmont (AGTR-4) and SS Simmons Victory becoming USS Liberty (AGTR-5).[32][33][34][35][36] All of these ships were decommissioned and struck from the Naval Vessel Register in 1969 and 1970.

Between 1955 and 1959, 16 former Liberty ships were repurchased by the United States Navy and converted to the Guardian-class radar picket ships for the Atlantic and Pacific Barrier.

As late as December 1947, Robert Dale Owen, renamed Kalliopi and sailing under the Greek flag, broke in three and sank in the northern Adriatic Sea after hitting a mine.[30] Other Liberty ships lost postwar to mines include John Woolman, Calvin Coolidge, Cyrus Adler, and Lord Delaware.[31]

Some Liberty ships were lost after the war to naval mines that were inadequately cleared. Pierre Gibault was scrapped after hitting a mine in a previously cleared area off the Greek island of Kythira in June 1945,[26] and the same month saw Colin P. Kelly Jnr take mortal damage from a mine hit off the Belgian port of Ostend.[27] In August 1945, William J. Palmer was carrying horses from New York to Trieste when she rolled over and sank 15 minutes after hitting a mine a few miles from destination. All crew members and six horses were saved.[28] Nathaniel Bacon ran into a minefield off Civitavecchia, Italy in December 1945, caught fire, was beached, and broke in two; the larger section was welded onto another Liberty half hull to make a new ship 30 feet longer, named Boccadasse.[29]

The term "Liberty-size cargo" for 10,000 long tons (10,000 t) may still be heard in the shipping business.

and the Andreadis, Tsavliris, Achille Lauro, Grimaldi and Bottiglieri families were known to have started their fleets by buying Liberty ships. Weyerhaeuser operated a fleet of six Liberty Ships (which were later extensively refurbished and modernized) carrying lumber, newsprint, and general cargo for years after the end of the war. [25] [24] More than 2,400 Liberty ships survived the war. Of these, 835 made up the postwar cargo fleet. Greek entrepreneurs bought 526 ships and Italians bought 98. Shipping magnates like John Fredriksen, John Theodoracopoulos,

SS Jeremiah O'Brien

After the war

The issue of hull cracks caused concern with the United States Coast Guard recommending Liberty ships be withdrawn from troop carrying in February 1944 but military commitments required their continued use.[20] The more direct problem was the general unsuitability of the ships as troop transports, particularly with the hasty conversions in 1943, that generated considerable complaints regarding mess and sanitation facilies, food and water storage and capacities, ventilation and heating and lack of medical facilities.[20] After Allied victory in North Africa about 250 Liberties were engaged in transporting prisoners of war to the United States.[23] By November 1943 the Army's Chief of Transportation, Maj. Gen. Charles P. Gross, and WSA, whose agents operated the ships, reached agreement on improvements, but operational requirements were then forcing an increase of the maximum number of troops transported on a Liberty from 350 to 500.[20] The increase in production of more suitable vessels did allow for returning the hastily converted Liberty ships to cargo only operations by May 1944.[20] Despite complaints, reservations, Navy requesting its personnel not travel aboard Liberty troopers and even Senate comment the military necessities required use of the ships, with number of troops even being increased to 550 on 200 Liberty ships for redeployment to the Pacific, into the immediate postwar period in order to bring troops from overseas as quickly as possible.[20]

In September 1943 strategic plans and shortage of more suitable hulls required that Liberty ships be pressed into emergency use as troop transports with about 225 eventually converted for this purpose.[20] The first general conversions were hastily undertaken by the War Shipping Administration (WSA) so that the ships could join convoys on the way to North Africa for Operation Torch.[20] Even earllier the Southwest Pacific Area command's U.S. Army Services of Supply had converted at least one, William Ellery Channing, in Australia into an assault troop carrier with landing craft (LCIs and LCVs) and troops with the ship being reconverted for cargo after the Navy was given exclusive responsibility for amphibious assault operations.[21] Others in the Southwest Pacific were turned into makeshift troop transports for New Guinea operations by installing field kitchens on deck, latrines aft between #4 and #5 hatches flushed by hoses attached to fire hydrants and about 900 troops sleeping on deck or in 'tween deck spaces.[22] While most of the Liberties converted were intended to carry no more than 550 troops thirty-three were converted to transport 1,600 on shorter voyages from mainland U.S. ports to Alaska, Hawaii and the Caribbean.[23]

Use as troop ships

The Ministry of War Transport lent the British-built Empire Duke for testing purposes.[19] Constance Tipper of Cambridge University demonstrated that the fractures were not initiated by welding, but instead by the grade of steel used, which suffered from embrittlement.[18] She discovered that the ships in the North Atlantic were exposed to temperatures that could fall below a critical point when the mechanism of failure changed from ductile to brittle, and thus the hull could fracture rather easily. The predominantly welded (as opposed to riveted) hull construction then allowed cracks to run for large distances unimpeded. One common type of crack nucleated at the square corner of a hatch which coincided with a welded seam, both the corner and the weld acting as stress concentrators. Furthermore, the ships 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. Various reinforcements were applied to the Liberty ships to arrest the crack problems, and the successor design, the Victory ship, was stronger and less stiff to better deal with fatigue.

Early Liberty ships suffered hull and deck cracks, and a few were lost to such structural defects. During World War II, there were nearly 1,500 instances of significant brittle fractures. Twelve ships, including three of the 2,710 Liberties built, broke in half without warning, including the SS John P. Gaines,[16][17] which sank on 24 November 1943 with the loss of 10 lives. Suspicion fell on the shipyards which had often used inexperienced workers and new welding techniques to produce large numbers of ships in great haste.[18]

Hull cracks


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 new-build 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 below decks to shut down his engines after a 13 April 1945 explosion, an act that won him a posthumous Merchant Marine Distinguished Service Medal.[13] In 1950, a "new" liberty ship was constructed by Industriale Maritime SpA, Genoa, Italy by using the bow section of Bert Williams and the stern section of Nathaniel Bacon, both of which had been wrecked. The new ship was named SS Boccadasse, and served until scrapped in 1962.[14][15]

Six Liberty ships were converted at Point Clear, Alabama, by the United States Army Air Force into floating aircraft repair depots, operated by the Army Transport Service, starting in April 1944. The secret project, dubbed "Project Ivory Soap", provided mobile depot support for B-29 Superfortress bombers and P-51 Mustang fighters based on Guam, Iwo Jima, and Okinawa beginning in December 1944. The six ARU(F)s (Aircraft Repair Unit, Floating), however, were also fitted with landing platforms to accommodate four Sikorsky R-4 helicopters, where they provided medical evacuation of combat casualties in both the Philippine Islands and Okinawa.[12]

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 short tons (1,400 t) of explosives still on board, enough to match a small nuclear weapon should they ever go off.[11] One Liberty ship that did explode was the SS E. A. Bryan which detonated with the energy of 2,000 tons of TNT (8,400 GJ) in July 1944 as it was being loaded, killing 320 sailors and civilians in what was called the Port Chicago disaster. Another Liberty ship that exploded was the rechristened SS Grandcamp, which caused the Texas City Disaster on 16 April 1947, killing at least 581 people.

Eastine Cowner, a former waitress, at work on the Liberty ship Office of War Information documenting the work of African-Americans in the war effort.

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


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