At 10.00 hours on 12 Sep 1942 the unescorted Stanvac Melbourne (Master Andrew T. Lagan) was hit on the port side by two torpedoes from U-515 about 15 miles southeast of Emerald Shoals off Trinidad. The first torpedo struck just forward of the bridge and the second just aft of the bridge and developed a 25° list to port and kept headway until the engines were stopped. The 40 crew members and nine armed guards abandoned ship in three lifeboats, except the master, the second mate, the radio operator and a seaman. At 10.20 hours, a first coup de grâce missed, but a second hit four minutes later the engine room in the stern and blew holes in both sides of the vessel. The remaining men now abandoned ship by jumping overboard and were picked up by the boats. About one hour later, the tanker turned over and sank by the stern with her bow straight up. One crew member was lost. At daybreak, the three lifeboats headed for Trinidads and that night made landfall near Toco Point, where they were met by natives and later taken to Port of Spain. On 16 September, the survivors were repatriated aboard an US Army transport.

The master Andrew T. Lagan survived both U-boat attacks on the Stanvac Melbourne, but died when his next ship, the Brilliant was torpedoed by U-43 (Schwantke) on 18 Nov 1942.