Moosehead was built as the commercial steamer SS Moosehead in 1911 by Bath Iron Works at Bath, Maine, Maine. On 13 November 1917, the U.S. Navy's 1st Naval District in northern New England inspected her for possible World War I service and, found her acceptable. She was assigned the naval registry identification number 2047 and earmarked for use as a "mine planter" (minelayer). The Navy authorized the Commandant of the 1st Naval District to accept Moosehead with full title from the United States Shipping Board when she was offered for delivery. He was also told that instructions for conversion of Moosehead into a transport for special service would be furnished at some future time.