At 00.18 hours on 27 May, 1942, the unescorted Polyphemus (Master C. Koningstein) was hit in the stern by two torpedoes from U-578 about 340 miles north of Bermuda and sank by the stern at 01.01 hours. On 25 November, the ship had picked up 14 survivors from a lifeboat of Norland, which had been sunk by U-108 (Scholtz) five days earlier. 15 Chinese crew members were killed in the explosions and the survivors abandoned ship in five lifeboats. The U-boat surfaced and questioned the first officer H. Brandenburg. He gave informations about the name of the vessel and the cargo, but not the name of the port of destination. Some cigarettes and the heading for New York were given to the survivors before the U-boat left. Rehwinkel obviously did not like the Dutch master, because he wrote in the KTB ein typisch vollgefressener Holländer.

The survivors in three lifeboats landed at Nantucket Island, Connecticut. The men in the two remaining boats were rescued by a Portugese ship after one week and landed at New Bedford. On 29 May, one of these lifeboats had been spotted by U-566 (Borchert) and was provided with water and the actual position.