At 14:36 on 13 September "U-594" fired a spread of three torpedoes at the 6,131-ton merchant ship "Stone Street", owned by the Waterman Steamship Corporation of Mobile, Alabama, but sailing under the Panamanian flag. The ship was about from the main convoy having developed problems with her boilers. One torpedo hit the ship in the engine room, and she listed and finally sank at 15:50. The master, 39 crewmen and 12 armed guards abandoned ship in a lifeboat and raft. Eleven crewmen and two armed guards were lost. The U-boat surfaced and took the survivors on board to be questioned, and provided them with supplies of whiskey, food, cigarettes and matches before returning all but the master (who was kept as a prisoner) to their lifeboats. They were picked up on 19 September by the merchant ship "Irish Larch".