12. A successor to the Liberty ships addressed some of their shortcomings
In February 1942 the newly formed United States War Shipping Administration addressed the already well-known problems facing the Liberty ships. Chief among them was speed, or rather, the lack thereof. Cruising at a mere eleven knots, Liberty ships presented easy targets for German U-boats and Luftwaffe aircraft. They also lacked the carrying capacity to meet the demands of the expanding forces of the Allies overseas. A new design type designated the Victory ships, permitted greater carrying capacity at higher sustained speeds. As with the Liberty ships, the hulls were welded rather than riveted, and the problems with hull cracking were addressed by placing the welds further apart, which provided more flexibility. Eventually, six American shipyards completed 534 Victory ships under contract with the Maritime Commission.
Delivery of the Victory ships proved slow; by early 1944 it was evident that not enough could be completed to support the planned invasions of Europe. Indeed, by May, one month before the invasion at Normandy, only a handful of Victory ships were available for service. War planners had recognized the potential shortage in early 1943. That led to the decision that Victory ships would supplement, but not replace, Liberty ships. Production of the latter not only continued but increased. Despite the losses of ships in the North Atlantic, which persisted throughout 1943, the speed with which Liberty ships were completed made them irreplaceable. The bulk of the supplies necessary for the invasion of Europe and sustaining the troops ashore in France traveled by Liberty ships. So did the American Lend-Lease supplies to Great Britain and the Soviet Union, often at severe risk to the ships’ civilian crews.