U.S. Army ships built on wheels. The main section of the pre-fabricated superstructure of a U.S.

U.S. Army ships built on wheels. The main section of the pre-fabricated superstructure of a U.S. Army FP (freight-passenger) vessel is lowered to the hull section which is cradled on a mobile carriage with steel wheels fitting on rails, at a shipyard in the U.S. Pacific Coast State of California. Parts of the 175-foot-long vessels are built inland, then transported 35 miles by truck to the yard where they are assembled in production-line fashion. The mobile carriages move on rails which lead down into the water to a depth where to the ships can float free.