On the night of 23 October, "Turner" was acting as an advance ASW escort for the convoy when she picked up an unidentified surface contact on her SG radar. At 19:43, about 11 minutes after the initial radar contact, "Turner"s lookouts made visual contact with what proved to be a German submarine running on the surface, decks awash, at about distance. Almost simultaneously, "Turner" turned hard to starboard and opened fire with her , Bofors, and Oerlikon guns. During the next few seconds, the destroyer scored one hit on the U-boat's conning tower as well as several 40- and 20-millimeter hits there and elsewhere. The submarine began to dive immediately and deprived "Turner" of any opportunity to ram her. However, while the U-boat made her dive, "Turner" began a depth-charge attack. She fired two charges from her port K-gun battery, and both appeared to hit the water just above the submerged U-boat. Then, as the destroyer swung around above the U-boat, "Turner" rolled a single depth charge off her stern. Soon after the three depth charges exploded, "Turner" crewmen heard a fourth explosion, the shock from which caused the destroyer to lose power to her SG and SD radars, to the main battery, and to her sound gear. It took her at least 15 minutes to restore power entirely.