sentences:  Aker American Shipping builds merchant vessels for companies operating under the Jones Act, and through its subsidiaries, owns and leases those ships as well.The Jones Act requires all water transport between US ports to be operated by US-flag ships and requires US-flag ships to be built in US shipyards, owned by US citizens, and operated by an American crew.Aker Philadelphia Shipyard, originally Kværner Philadelphia Shipyard, began as a product of a partnership of public and private investments used to rebuild and convert of the former Philadelphia Naval Shipyard, which was closed in 1995.