Bath originally was authorized as a patrol gunboat with the hull number PG-163, but she was redesignated as a patrol frigate with the hull number PF-55 on 15 April 1943. She was laid down under a Maritime Commission contract as Maritime Commission Type T.S2-S2-AQ1 Hull 1480 on 23 August 1943 by Froemming Brothers, Inc., at Milwaukee. She was launched on 14 November 1943, sponsored by Mrs. Fred R. E. Dean, then moved in an incomplete state to New Orleans, where she was completed by Pendleton Shipyards. She was commissioned on 9 September 1944 with a United States Coast Guard crew and Commander John R. Stewart, USCG, in command.