"U-353" was the seventh or eighth boat in the patrol line and remained in position for a week. On sighting a fast independently sailing ship at a range of about 4,000 yards, she altered course to intercept it, but lost contact. Early on 10 October, the U-boat sighted another ship, estimated to be of about 15,000 tons, sailing independently. The U-boat pursued her, but lost her in rapidly worsening weather, abandoning the chase and returning to the patrol line. The next day, 11 October, reported sighting a convoy of three fast ships and three destroyers, "U-353" was one of several U-boats ordered to pursue them.