The destroyer escort spent the next few weeks at Casco Bay, Maine in refresher training. On 25 June, she joined on another hunter-killer patrol in the Atlantic and in the West Indies. The group's first mission was to investigate a U-boat reported to be just south of Newfoundland. "Thomas" rammed on 5 July, sinking the submarine, and TG 22.10 returned to Boston, Massachusetts to land prisoners and make repairs. The hunter-killer group departed Boston again on the 10th, bound for the West Indies to search for a U-boat that had torpedoed several ships in the area. On 16 July, after a plane made a contact sixty miles from the group, "Bostwick" joined "Bronstein" in a night-long search for the supposed submarine. The effort proved futile, however, and the two destroyer escorts rejoined TG 22.10 at San Juan on 18 July. "Bostwick" returned to New York on 25 August for a 10-day availability.