 The time for building the ships fell dramatically, as experience was gained by the workers in their jobs and by the management in each yard in the most effective means of construction.One factor that played a major part in getting the productivity so high was the use of welding and prefabrication, in which large sections of each ship's hull or superstructure was built off the building ways and then moved into position only when the assemblers were ready.This method became so efficient that for a single Liberty ship to be fully assembled, launched, outfitted, and delivered went from a program average of almost 240 days at the beginning of 1942 to only 56 days at the end of the year.