United States Coast Guard Cutter Spencer (WPG-36) during WWII in the Atlantic1943, Spencer sank the German submarine U-175 on April 17, 1943. Sinking of German submarine U-175, April 1943. The submarine was sunk off south-west of Ireland by USCGC Spencer (WPG-36) on April 17, 1943. These ships in the convoy being shielded by the U.S. Coast Guard Cutter USCGC SPENCER (WPG-36) steam past the warship just before the latter detects the underseas raider and swings into action. The U-Boat, endeavoring to break into the center of the convoy, was sunk." Date: 17 April 1943.