Patchogue was laid down on 29 May 1942 at the Defoe Shipbuilding Company in Bay City, Michigan; launched as USS PC-586 on 15 July 1942; and commissioned on 5 October 1942. After sea trials in the Gulf of Mexico, PC-586 transited the Panama Canal and served as an escort craft along the west coast of the United States. Her coastal operations were ultimately extended to the Hawaiian Islands, and during the period of 1 August through 31 December 1943, she was assigned to Commander, Hawaiian Sea Frontier, for duty. During this time she rendered valuable service as a training craft in the area of Pearl Harbor. She likewise performed patrol and convoy escort missions in Hawaiian waters. A convoy escort mission took PC-586 to Saipan on 23 July 1944.