Hammac was a steam tank ship built in 1920–1921 by Bethlehem Shipbuilding Corporation of Alameda for the United States Shipping Board as part of the wartime shipbuilding program of the Emergency Fleet Corporation (EFC) to restore the nation's Merchant Marine. Early in 1923 the vessel together with two other tankers was sold to General Petroleum Corporation and renamed Emidio. The tanker spent the vast majority of her career carrying oil along the West Coast of the United States as well as between West and East coast. In December 1941 she was shelled and damaged by the and eventually wrecked with a loss of five crewmen. Design and construction After the United States entry into World War I, a large shipbuilding program was undertaken to restore and enhance shipping capabilities both of the United States and their Allies. As part of this program, EFC placed orders with nation's shipyards for a large number of vessels of standard designs. Design 1047 tank ship was a standard tanker of approximately 10,100 tons deadweight designed by Bethlehem Shipbuilding Corp. and adopted by USSB. Hammac was part of the order for six vessels placed by USSB with Bethlehem Shipbuilding Corporation on 30 April 1918 and was laid down on 30 November 1920 at the builder's shipyard at Potrero Point and launched on 25 May 1921 (yard number 5274). The ship was built on the Isherwood principle of longitudinal framing providing extra strength to the body of the vessel and had two main decks. The tanker had her machinery placed aft and a cargo pump room located amidships, and had cargo tanks constructed throughout the vessel with a total capacity to carry 3,369,862 gallons of oil. In addition, the ship had four booms and four winches to handle deck load and dry hold cargoes. The vessel had electric lights installed along the decks and was also equipped with wireless of De Forest type. As built, the ship was long (between perpendiculars) and abeam, and had a depth of . Hammac was originally assessed at and and had deadweight of approximately 10,000. The vessel had a steel hull, and a single 422 nhp () vertical triple expansion steam engine, with cylinders of , and diameter with a stroke, that drove a single screw propeller and moved the ship at up to . The steam for the engine was supplied by three single-ended Scotch boilers fitted for oil