|John Abbott posted|
One revolution was to build a lot of shipyards. America had eighteen shipyards building Liberty Ships. Many of those shipyards included a steel plant so that the supply chain was short. Another aspect of the revolution is that they were all using a standard design that was a modification of a British design. No time was wasted by a design phase. And a standardized design allowed the efficiency of interchangeable parts no matter which shipyard built the ship. For example, a part developed by a subcontractor could be used by all of the shipyards during construction, and then used later, if needed, for repairs. That design also used an obsolete coal-fired steam engine instead of a steam turbine. One reason is that Britain had plenty of coal mines, but very few oil wells. Another reason is that America had very little industrial capacity to build the gear reduction trains needed by steam turbines. Furthermore, ship crews had decades of experience maintaining steam engines and the open design also made maintenance easier. [Wikipedia-Liberty]
|By United States Maritime Commission photo - Scanned from Live (program published by Project Liberty Ship for cruises of the Liberty ship SS John W. Brown), 2013 edition, page 11. Additional descriptive information from p. 10 of the same publication., Public Domain, Link|
One of the modifications the Americans made to the British design was to use welding instead of rivets. This is the change credited by [kiel-kap_3] for the improved output. Using rivets did not avoid having to train the workers how to weld because they were recently hired women who needed to be trained anyhow. So they might as well be taught the new technique instead of the obsolete technique. Another modification was that American ships switched from coal to oil boilers.
As the at the top shows, an alternative to prefabrication construction techniques was to build a shipyard with lots of dry docks.
The cracks where not at the welds as was first assumed, but the welded joints did contribute to the problem of broken ships because a weld propagates a crack. In riveted ships the crack stopped at the end of a plate so it did not grow to a catastrophic length. The other issue was that some of the steel plants built for the Liberty Ship program produced steel that had a high ductile-to-brittle transformation temperature. (Actually, it wasn't the plants themselves, it was their source of raw materials. The steel had too much phosphorus. What caused embrittlement below a threshold temperature was not determined until about 1950. [kiel-kap_9] Modern steels have a threshold below freezing, which is good enough for ships. But now I understand why they talk about steel getting cold in northern Alaska as such a big deal.)