 Crewed by 34 merchant seamen, "Cornish" operated on the Great Lakes.The U.S. Navy acquired "Cornish" under charter from Eastern Shipbuilding Lines, Inc., of Boston, Massachusetts, on 29 December 1941.She was converted at a cost of $250,000 for use as a patrol vessel by the Sullivan Drydock and Repair Corporation of New York City, classified as a "miscellaneous district auxiliary" (YAG), and commissioned as the patrol vessel USS "YAG-9" on 3 January 1942.