 SS Jeremiah O'Brien, one of four surviving Liberty ships, photographed in 2022 | |
| Class overview | |
|---|---|
| Name | Liberty ship |
| Builders | 18 shipyards in the United States |
| Cost | US$2 million ($45 million in 2024) per ship[1] |
| Planned | 2,751 |
| Completed | 2,710[citation needed] |
| Active | 2 (Travelingmuseum ships) |
| Preserved | 4 |
| General characteristics | |
| Class & type | Cargo ship |
| Tonnage | 7,176 GRT, 10,865 DWT[2] |
| 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) |
| Propulsion |
|
| Speed | 11–11.5knots (20.4–21.3 km/h; 12.7–13.2 mph) |
| Range | 20,000 nmi (37,000 km; 23,000 mi) |
| Complement |
|
| Armament | Stern-mounted 4-in (102 mm) deck gun for use against surfaced submarines, variety ofanti-aircraft guns |
Liberty ships are aclass ofcargo ship built in the United States duringWorld War II under theEmergency Shipbuilding Program. Although British in concept,[3] the design was adopted by the United States for its simple, low-cost construction.Mass-produced on an unprecedented scale, the Liberty ship came to symbolize U.S. wartime industrial output.[4]
The class was developed to meet British orders for transports to replace ships that had been lost. Eighteen Americanshipyards built 2,710 Liberty ships between 1941 and 1945 (an average of three ships every two days),[5] easily the largest number of ships ever produced to a single design.[citation needed]
The Liberty ship was effectively superseded by theVictory ship, a somewhat larger, materially faster, more modern-powered vessel of generally similar design. A total of 531 Victory ships were built in between 1944 and 1946.[6][7]
Liberty ship production mirrored (albeit on a much larger scale) the manufacture of "Hog Islander" and similar standardized ship types during World War I. The immensity of the effort, the number of ships built, the role offemale workers in their construction, and the survival of some far longer than their original five-year design life combine to make them the subject of much continued interest.[citation needed]
In 1936, the AmericanMerchant Marine Act was passed to subsidize the annual construction of 50 commercial merchant vessels which could be used in wartime by theUnited States Navy as naval auxiliaries, crewed byU.S. Merchant Mariners. The number was doubled in 1939 and again in 1940 to 200 ships a year. Ship types included two tankers and three types of merchant vessel, all to be powered bysteam turbines. Limited industrial capacity, especially for reduction gears, meant that relatively few of these designs of ships were built.
However, in 1940, the British government ordered 60Ocean-classfreighters 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 horsepower (1,900 kW)compound steam engine of outdated but reliable design. Britain specified coal-fired plants, because it then had extensive coal mines and no significant domestic oil production.[9]
The predecessor designs, which included the "Northeast Coast, Open Shelter Deck Steamer", were based on a simple ship originally produced inSunderland byJ.L. Thompson & Sons based on a 1939 design for a simpletramp steamer, which was cheap to build and cheap to run (seeSilver Line). Examples include SSDorington Court built in 1939.[10] The order specified an 18-inch (0.46 m) increase indraft 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, SSOcean Vanguard, waslaunched on 16 August 1941.
The design was modified by theUnited 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 muchriveting, which accounted for one-third of the labor costs, withwelding, 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 byHenry J. Kaiser known as theSix Companies. Liberty ships were designed to carry 10,000 long tons (10,200 t) of cargo, usually one type per ship, but, during wartime, generally carried loads far exceeding this.[11]
On 27 March 1941, the number oflend-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 basic EC2-S-C1 cargo design was modified during construction into three major variants with the same basic dimensions and slight variance in tonnage. One variant, with basically the same features but different type numbers, had four rather than fiveholds served by large hatches andkingpost with large capacity booms. Those four hold ships were designated for transport of tanks and boxed aircraft.[12]
In the detailed Federal Register publication of the post war prices of Maritime Commission types the Liberty variants are noted as:[12]
In preparation for theNormandy landings and afterward to support the rapid expansion of logistical transport ashore a modification was made to make standard Liberty vessels more suitable for mass transport of vehicles and in records are seen as "MT" for Motor Transport vessels. As MTs four holds were loaded with vehicles while the fifth was modified to house the drivers and assistants.[13]
The modifications into troop transports also were not given special type designations.
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By 1941, thesteam turbine was the preferredmarine steam engine because of its greater efficiency compared to earlier reciprocatingcompound steam engines. Steam turbine engines however, required very precise manufacturing techniques to machine their complicateddouble helical reduction gears, and the companies capable of producing them were already committed to the large construction program forwarships. Therefore, a 140-short-ton (130 t)[14]vertical triple expansion 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, simplicity and familiarity to seamen. 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 m) long and 19 feet (5.8 m) tall—was designed to operate at 76rpm and propel a Liberty ship at about 11 knots (20 km/h; 13 mph).[15]
The ships were constructed of sections that were welded together. This is similar to the technique used byPalmer's atJarrow, northeast England, but substitutedwelding forriveting. Riveted ships took several months to construct. The work force was newly trained as the yards responsible had not previously built welded ships. As America entered the war, the shipbuilding yards employed women, to replace men who were enlisting in the armed forces.[16]
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The ships initially had a poor public image owing to their appearance. In a speech announcing the emergency shipbuilding program PresidentFranklin D. Roosevelt had referred to the ship as "a dreadful looking object", andTime called it an "Ugly Duckling". 27 September 1941 was dubbedLiberty Fleet Day to try to assuage public opinion, since the first 14 "Emergency" vessels were launched that day. The first of these wasSS Patrick Henry, launched by President Roosevelt. In remarks at the launch ceremony FDR citedPatrick Henry's 1775 speech that finished "Give me liberty or give me death!". Roosevelt said that this new class of ship would bring liberty to Europe, which gave rise to the name Liberty ship.
The first ships required about 230 days to build (Patrick Henry took 244 days), but the median production time per ship dropped to 39 days by 1943.[17] The record was set bySS Robert E. Peary, which was launched 4 days and 151⁄2 hours after thekeel had been laid, although thispublicity stunt was not repeated: in fact much fitting-out and other work remained to be done after thePeary 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 theDeclaration of Independence. Newsreel footage of the launching of the ship named for American authorJack London can be seen in the filmJack London. 17 of the Liberty ships were named in honor of outstanding African-Americans. The first, in honor ofBooker T. Washington, was christened byMarian Anderson in 1942, and theSS Harriet Tubman, recognizing the only woman on the list, was christened on 3 June 1944.[18]
Any group that raisedwar bonds worth $2 million could propose a name. Most bore the names of deceased people. The only living namesake was Francis J. O'Gara, thepurser ofSS Jean Nicolet, who was thought to have been killed ina submarine attack, but in fact survived the war in a Japaneseprisoner of war camp; seeUSS Outpost. Not named after people were:SS Stage Door Canteen, named after theUSO club in New York; andSS U.S.O., named after theUnited Service Organizations (USO).[19]
Another notable Liberty ship wasSS Stephen Hopkins, which sank the Germancommerce raiderStier in a ship-to-ship gun battle in 1942 and became the first American ship to sink a German surface combatant.
The wreck ofSS Richard Montgomery lies off the coast ofKent with 1,500short tons (1,400tonnes) ofexplosives still on board, enough to match a very small yieldnuclear weapon should they ever go off.[20][21]SS E. A. Bryan detonated with the energy of 2,000tons of TNT (8,400 GJ) in July 1944 as it was being loaded, killing 320 sailors and civilians in what was called thePort Chicago disaster. Another Liberty ship that exploded was the rechristenedSS Grandcamp, which caused theTexas City Disaster on 16 April 1947, killing at least 581 people.
Six Liberty ships were converted atPoint Clear, Alabama, by theUnited States Army Air Force, into floating aircraft repair depots, operated by theArmy Transport Service, starting in April 1944. The secret project, dubbed "Project Ivory Soap", provided mobile depot support forB-29 Superfortress bombers andP-51 Mustang fighters based onGuam,Iwo Jima, andOkinawa beginning in December 1944. The six ARU(F)s (Aircraft Repair Unit, Floating), however, were also fitted with landing platforms to accommodate fourSikorsky R-4 helicopters, where they provided medical evacuation of combat casualties in both thePhilippine Islands and Okinawa.[22]
The last new-build Liberty ship constructed wasSS Albert M. Boe, launched on 26 September 1945 and delivered on 30 October 1945. She was named after the chief engineer of aUnited 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 posthumousMerchant Marine Distinguished Service Medal.[23] In 1950, a "new" liberty ship was constructed by Industriale Maritime SpA,Genoa, Italy by using the bow section ofBert Williams and the stern section ofNathaniel Bacon, both of which had been wrecked. The new ship was namedSS Boccadasse, and served until scrapped in 1962.[24][25]
Several designs of mass-produced petroleum tanker were also produced, the most numerous being theT2 tanker series, with about 490 built between 1942 and the end of 1945.
Early Liberty ships suffered hull and deck cracks, and a few were lost due to such structural defects. During World War II there were nearly 1,500 instances of significantbrittle fractures. Twelve ships, including three of the 2,710 Liberty ships built, broke in half without warning, includingSS John P. Gaines,[26][27] 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.
TheMinistry of War Transport borrowed the British-builtEmpire Duke for testing purposes.[28]Constance Tipper ofCambridge University demonstrated that the fractures did not start in the welds, but were due to theembrittlement of the steel used.[29] When used in riveted construction, however, the same steel did not have this problem. Tipper discovered that at a certain temperature, the steel the ships were made of changed from beingductile tobrittle, allowing cracks to form and propagate. This temperature is known as thecritical ductile-brittle transition temperature. Ships in the North Atlantic were exposed to temperatures that could fall below this critical point.[30] The predominantly welded hull construction, effectively a continuous sheet of steel, allowed small cracks to propagate unimpeded, unlike in a hull made of separate plates riveted together. 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 asstress concentrators. Furthermore, the ships were frequently grossly overloaded, greatly increasing stress, and some of the structural problems occurred during or after severe storms that would have further increased stress. Minor revisions to the hatches and various reinforcements were applied to the Liberty ships to arrest the cracking problem. These are some of the first structural tests that gave birth to the study of materials. The successorVictory ships used the same steel, also welded rather than riveted, but spacing between frames was widened from 30 inches (760 mm) to 36 inches (910 mm), making the ships less stiff and more able to flex.[citation needed]
The sinking of the Liberty ships led to a new way of thinking about ship design and manufacturing. Ships today[when?] avoid the use of rectangular corners to avoidstress concentration. New types of steel were developed that have higherfracture toughness, especially at lower temperatures. In addition, more talented and educated welders can produce welds without, or at least with fewer, flaws. While the context and time in which Liberty ships were constructed resulted in many failures, the lessons learned led to new innovations that allow for more efficient and safer shipbuilding today.[31]
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.[32] The first general conversions were hastily undertaken by theWar Shipping Administration (WSA) so that the ships could join convoys on the way to North Africa forOperation Torch.[3] Even earlier theSouthwest 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 andLCVs) and troops with the ship being reconverted for cargo after the Navy was given exclusive responsibility for amphibious assault operations.[33] 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.[34] While most of the Liberty ships 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.[35]
The problem of hull cracks caused concern with theUnited States Coast Guard, which recommended that Liberty ships be withdrawn from troop carrying in February 1944 although military commitments required their continued use.[3] 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 poor mess, food and water storage, sanitation, heating / ventilation and a lack of medical facilities.[3] After the Allied victory in North Africa, about 250 Liberty ships were engaged in transporting prisoners of war to the United States.[35] 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 forced an increase of the maximum number of troops transported in a Liberty from 350 to 500.[3] The increase in production of more suitable vessels did allow for returning the hastily converted Liberty ships to cargo-only operations by May 1944.[3] Despite complaints, reservations, Navy requesting its personnel not travel aboard Liberty troopers and even Senate comment, the military necessities required use of the ships. The number of troops was increased to 550 on 200 Liberty ships for redeployment to the Pacific. The need for the troopship conversions persisted into the immediate postwar period in order to return troops from overseas as quickly as possible.[3]
On 27 September 1942 theSS Stephen Hopkins was the only US merchant ship to sink a German surface combatant during the war. Ordered to stop,Stephen Hopkins refused to surrender, so the heavily armed Germancommerce raiderStier and her tenderTannenfels with one machine gun opened fire. Although greatly outgunned, the crew ofStephen Hopkins fought back, replacing theArmed Guard crew of the ship's single 4-inch (100 mm) gun with volunteers as they fell. The fight was short, and both ships were wrecks.[36]
On 10 March 1943SS Lawton B. Evans became the only ship to survive an attack by theGerman submarine U-221.[37] The following year from 22 to 30 January 1944,Lawton B. Evans was involved in theBattle of Anzio in Italy. It was under repeated bombardment from shore batteries and aircraft for eight days. It endured a prolonged barrage of shelling, machine-gun fire and bombs. The ship shot down five German planes.[38]
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 includingJohn Fredriksen,[39] John Theodoracopoulos,[40]Aristotle Onassis,[41]Stavros Niarchos,[41]Stavros George Livanos, the Goulandris brothers,[41] and the Andreadis, Tsavliris,Achille Lauro, Grimaldi and Bottiglieri families were known to have started their fleets by buying Liberty ships.Andrea Corrado, the dominant Italian shipping magnate at the time, and leader of the Italian shipping delegation, rebuilt his fleet under the programme. 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.
Some Liberty ships were lost after the war tonaval mines that were inadequately cleared.Pierre Gibault was scrapped after hitting a mine in a previously cleared area off the Greek island ofKythira in June 1945,[42] and the same month sawColin P. Kelly Jnr take mortal damage from a mine hit off the Belgian port ofOstend.[43] 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.[44]Nathaniel Bacon ran into a minefield offCivitavecchia, 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, namedBoccadasse.[45]
As late as December 1947,Robert Dale Owen, renamedKalliopi and sailing under the Greek flag, broke in three and sank in the northernAdriatic Sea after hitting a mine.[46] Other Liberty ships lost to mines after the end of the war includeJohn Woolman,Calvin Coolidge,Cyrus Adler, andLord Delaware.[47]
On 16 April 1947, a Liberty ship owned by theCompagnie Générale Transatlantique called theGrandcamp (originally built as the SS Benjamin R. Curtis) docked in Texas City, Texas to load a cargo of 2,300 tons ofammonium nitrate fertilizer. A fire broke out on board which eventually caused the entire ammonium nitrate cargo to explode. The massive explosion levelled Texas City and caused fires which detonated more ammonium nitrate in a nearby ship and warehouse. It was one of the largest non-nuclear explosions in US history. This incident is known as theTexas City disaster today.[48]
On 21 December 1952, the SSQuartette, a 422-foot-long (129 m) Liberty Ship of 7,198gross register tons, struck the eastern reef of thePearl and Hermes atoll at a speed of 10.5 kn (19 km/h; 12 mph). The ship was driven further onto the reef by rough waves and 35 mph (56 km/h) winds, which collapsed the forward bow and damaged two forward holds.[49] The crew was evacuated by theSSFrontenac Victory the following day. Thesalvage tugOno arrived on 25 December to attempt to tow the ship clear, but persistent stormy weather forced a delay of the rescue attempt. On 3 January, before another rescue attempt could be made, the ship's anchors tore loose and theQuartette was blown onto the reef, and deemed atotal loss. Several weeks later, it snapped in half at thekeel and the two pieces sank.[50] The wreck site now serves as anartificial reef which provides a habitat for many fish species.[51]
In 1953, theCommodity Credit Corporation (CCC), began storing surplus grain in Liberty ships located in theHudson River,James River, Olympia, and AstoriaNational Defense Reserve Fleets. In 1955, 22 ships in theSuisun Bay Reserve Fleet were withdrawn to be loaded with grain and were then transferred to the Olympia Fleet. In 1956, four ships were withdrawn from the Wilmington Fleet and transferred, loaded with grain, to the Hudson River Fleet.[52]
Between 1955 and 1959, 16 former Liberty ships were repurchased by the United States Navy and converted to theGuardian-class radar picket ships for theAtlantic and Pacific Barrier.
In the 1960s, three Liberty ships and two Victory ships were reactivated and converted totechnical research ships with thehull classification symbol AGTR (auxiliary, technical research) and used to gather electronic intelligence and for radar picket duties by the United States Navy. The Liberty ships SSSamuel R. Aitken becameUSS Oxford, SSRobert W. Hart becameUSS Georgetown, SSJ. Howland Gardner becameUSS Jamestown with the Victory ships beingSS Iran Victory which becameUSS Belmont andSS Simmons Victory becomingUSS Liberty.[53][54][55][56][57] All of these ships weredecommissioned and struck from theNaval Vessel Register in 1969 and 1970.
From 1946 to 1963, thePacific Ready Reserve Fleet – Columbia River Group, retained as many as 500 Liberty ships.[58]
In 1946, Liberty ships weremothballed in theHudson River Reserve Fleet nearTarrytown, New York. At its peak in 1965, 189 hulls were stored there. The last two were sold for scrap to Spain in 1971 and the reserve permanently shut down.[59][60]
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Only two operational Liberty ships,SS John W. Brown andSS Jeremiah O'Brien, remain.John W. Brown has had a long career as aschool ship and many internal modifications, whileJeremiah O'Brien remains largely in her original condition. Both aremuseum ships that still put out to sea regularly. In 1994,Jeremiah O'Brien steamed from San Francisco to England and France for the 50th anniversary ofD-Day, the only large ship from the originalOperation Overlord fleet to participate in the anniversary. In 2008,SS Arthur M. Huddell, a ship converted in 1944 into a pipe transport to supportOperation Pluto,[61] was transferred to Greece and converted to a floating museum dedicated to the history of the Greek merchant marine;[62] although missing major components were restored this ship is no longer operational.
Liberty ships continue to serve in a "less than whole" function many decades after their launching. InPortland, Oregon, the hulls ofRichard Henry Dana andJane Addams serve as the basis of floating docks.[63]SS Albert M. Boe survives as theStar of Kodiak, a landlockedcannery, inKodiak Harbor at57°47′12″N152°24′18″W / 57.78667°N 152.40500°W /57.78667; -152.40500.
SS Charles H. Cugle was converted intoMH-1A (otherwise known as USSSturgis).MH-1A was afloating nuclear power plant and the first ever built.MH-1A was used to generate electricity at thePanama Canal Zone from 1968 to 1975. She was also used as a fresh water generating plant. She was anchored in theJames River Reserve Fleet.[64] The ship was dismantled in 2019 in Brownsville, Texas.[65]
Fifty-eight Liberty ships were lengthened by 70 feet (21 m) starting in 1958,[66] giving them additional carrying capacity at a small additional cost.[66][citation needed] The bridges of most of these were also enclosed in the mid-1960s in accordance with a design by naval architect Ion Livas.
In the 1950s, theMaritime Administration instituted the Liberty Ship Conversion and Engine Improvement Program, which had a goal to increase the speed of Liberty ships to 15 knots (28 km/h; 17 mph), 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.[67]SSBenjamin 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.SSThomas 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 three years. GTSWilliam 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.[68][69] All four vessels were fueled withBunker C fuel oil, thoughJohn Sergeant required a quality of fuel available at limited ports and also required further treatment to reduce contaminants.[70] Three were scrapped in 1971 or 1972 and the diesel-equippedThomas Nelson was scrapped in 1981.
In 2011, theUnited States Postal Service issued a postage stamp featuring the Liberty ship as part of a set on theU.S. Merchant Marine.[71]
Liberty ships were built at eighteen shipyards located along the U.S. Atlantic, Pacific and Gulf coasts:[72]
There are four surviving Liberty Ships.
mass-produced during the war, the Liberty Ship had become a symbol of the miracle of American production
(2,710 ships were completed, as one burned at the dock.)
Little Boy yield: 15 kilotons / Fat Man yield: 21 kilotons
The brittle fractures that occurred in the Liberty Ships were caused by low notch toughness at low temperature of steel at welded joint, which started at weld cracks or stress concentration points of the structure. External forces or residual stress due to welding progress the fracture. Almost all accidents by brittle fractures occurred in winter (low temperature). In some cases, residual stress is main cause of fracture.
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