The Hog Island Yard in World War I

The S.S. Mary Luckenbach, a Hog Island class freighter
It is often stated that the Liberty Ship was the first mass produced ship in shipbuilding history, that it was the first to make extensive use of prefabricated components, and that it was the first all welded ship to be produced in quantity. Only the third statement is true. During World War I, the government financed a large number of yards for war production of freighters. By one measure at least, some of these yards dwarfed the shipyards constructed during the Emergency Program of WWII. The largest of these yards, the Hog Island yard (Philadelphia) of the American International Corporation, boasted fifty ways; the largest Liberty yard counted just sixteen ways. The Hog Island yard produced 122 ships for a total 921,000 deadweight tons. Of these, 110 ships were of the prefabricated Hog Island type, a 7,600 ton cargo ship. The yard employed 30,000 workers at its peak and cost $65,000,000 to build. In addition, 3,000 subcontrac tors were used, to supply engines, boilers, propellors, shapes and plates. 88 steel shops were subcontracted to supply shapes and plates. There were other large yards. In Newark, NJ, the Submarine Boat Company operated a 28-way facility, and built 118 ships. The Bristol, PA, yard of the Merchant Shipbuilding Corporation delivered forty ships of 9,000 tons off twelve ways.
The figure below reproduces data on the speed of production of the 110 Hog Island type vessels. produced at the Hog Island yard. What is interesting about the data is that it exhibits very little of the pheneomenal increase in production speed obtained during the first two years of the Liberty Ship program. The first ship's keel, Quistconck, was laid on 12 February 1918 and required 294 days from keel laying to delivery. The quickest production time was 178 days. In contrast, in the major Liberty yards  production time declined from over 180 days for their first ships to as little as 20 days. Why were the gains in production speed so much slower aty Hog Island. One possibility is that he yard was fully established before the first keel was laid, so there was no capital expansion. But, as Thomas Heinrich (Ships for the Seven Seas, 1997) explains, the keel of Quistconck was laid in a half completed berth and "plant construction interfered with ship assembly, so that ship carpenters remained idle for weeks until constructions workers had completed the groundwork." (page 186).The second possibility is that there was really very little to learn. Despite the novel aspects of prefabricated production, the Hog Island yard continued to emply carpenters using traditional production techniques. Thus, initial production speeds were already close to the maxmiumum that could bhe achieved.
Production Speed in Days, Hog Island Type Vessels Built at the Hog Island Shipyard, 1918-1920.

Source: Hog Island News, 1921, p. 13. Copy from G.J. Fischer's files, Historian's Collection Box 31, Records of the US Maritime Commission, National Archives. The data underlying this graph are available as an excel file.