At 16.59 hours on 21 Feb, 1943, the Stigstad (Master Odd Pettersen) was hit on the starboard side by one torpedo from U-332 (Hüttemann) near tank #16. The ship had been in convoy ON-166 and was straggling since encountering a heavy storm. Only six minutes later, the tanker was hit amidships and in the engine room on the starboard side by two of four torpedoes from U-603 (Bertelsmann) and sank within 15 minutes. The 34 survivors abandoned ship in one lifeboat and were questioned by Hüttemann, who provided them with food supplies that he requested from the other U-boat just for the survivors.

On 7 March, the survivors in the lifeboat were picked up by the British fishing trawler Thomas Boot (Skipper A. Howie) in 52°30N/12°08W about 60 miles northwest of Valentia Island, Ireland. The next day, they were landed in Valentia where six men were admitted to a hospital.