Today in 1941, the cargo ship SS Henry Patrick was launched along with 13 sister ships during a Presidential launching ceremony in Baltimore, Maryland. These 14 vessels were the first Liberty ships, a class of cheap and quick-to-build cargo haulers that helped to carry the industrial output of wartime America to the battlefields of Europe and the Pacific.
The Liberty ships were 441.5' long and had a 57' beam. When fully loaded, they required almost 28 feet of water to stay afloat. Their top speed was 11.5 knots or almost 13 miles an hour. They could carry 9,100 tons of cargo, but many of the ships carried more than that on a regular basis.
The basic design for the Liberty ship dates to 1940, when the British government ordered 60 ships to help replace the merchant ships lost during the first year of World War Two. These were called Ocean-class ships and were built at American shipyards. They used coal instead of oil because while Great Britain had many coal mines, the country had no indigenous oil fields. The first of these vessels, Ocean Vanguard, was launched in August, 1941.
The United States Maritime Commission took the Ocean-class design and modified it so the ships could be built faster and for less money. The biggest design change was the decision to weld sections of the ship together instead of using rivets. Riveting accounted for as much as one-third of the labor cost of building a cargo ship, so the monetary savings for a fleet of Liberty ships was significant. The Liberty design also used oil for fuel instead of coal as the Ocean-class ships used.
A group of engineering and construction concerns known as the Six Companies were given a contract from the federal government to build the first Liberty Ships. Henry J. Kaiser, an industrialist and the head of the Six Companies, studied the automotive industry and came to the conclusion that large ships could be built in much the same way as automobiles. This assembly line method was used by all the shipyards which built Liberty ships and was so successful that, by the end of the war, a ship went from a stack of steel plates to a finished product in just 30 days. Over the course of the war, the average construction time was 42 days.
During 1941, the US government increased the number of ships that were to be delivered to Great Britain from the original 60 to 200, then 306. 117 of these would be LIberty ships. By the time the United States entered the Second World War in December, 1941, the Six Companies' shipyards had much experience with the cargo ships' design. In all, sixteen American shipyards on both coasts built the Liberty ships; 2,751 of them were built between 1941 and 1945. The ships were initially named after famous Americans, starting with the signers of the Declaration of Independence. However, any group which raised $2 million worth of war bonds could name a ship (within reason, of course). This is how the US government came to own ships named SS Stage Door Canteen and SS U.S.O…
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