 "Unalga" served as a patrol cutter for the Coast Guard at San Juan performing law enforcement duties until 1 November 1941 when President Franklin D. Roosevelt transferred by executive order the whole Coast Guard to the control of the Department of the Navy.The Navy assigned her to anti-submarine patrols operating out of San Juan.In September 1943, "Unalga" was assigned to the Motor Torpedo Boat Squadron Training Center at Melville, Rhode Island where she served as a "target ship" for PT boats and then recovered the test torpedoes.