13. The Liberty ships suffered from being underpowered due to logistics considerations
Contrary to popular belief, the US Navy underwent huge modernization and expansion years before the Japanese attack on Pearl Harbor. After several Congressional acts passed in the 1930s authorized naval expansion, the United States began building cruisers, battleships, destroyers, aircraft carriers, and support ships. When Japan bombed Pearl Harbor, 10 fast battleships were under construction in American shipyards with two more on order (they were later canceled). The preferred method of maritime propulsion at the time were by steam turbines. The expansion put pressure on the shipyards and their subcontractors to manufacture technologically up-to-date designs, and those companies capable of producing them were backlogged with orders. Powering the Liberty ships presented problems to their designers, who couldn’t wait in line for propulsion plants.
To resolve the problem, designers of the Liberty ships deliberately chose a largely obsolete design for the ships’ engines. The engine selected offered the advantages of being constructed by less-skilled and experienced manufacturers, due to its being less complex. It also offered easier maintenance by the crews at sea. The engines, which weighed approximately 140 tons when assembled, used interchangeable parts, and eventually, 18 manufacturers built them and delivered them to the slipways for installation by the shipyard. The disadvantage presented came from the engine’s relative lack of power. Though rugged and easy to maintain, the triple-expansion engine provided just enough power to allow the ship to cruise at 11 knots. Habitual overloading of the Liberty ships by port directors often led to even slower speeds, placing ship, cargo, and crew at increased risk from the German and Japanese navies.