German submarine U - 511 German submarine " U - 511 " was a Type IXC U - boat of the Nazi German " Kriegsmarine " during World War II . The submarine was laid down on 21 February 1941 at the Deutsche Werft yard in Hamburg as ' werk ' 307 , launched on 22 September 1941 and commissioned on 8 December 1941 under the command of " Kapitänleutnant " Friedrich Steinhoff . After training with the 4th U - boat Flotilla , from May 1942 , " U - 511 " was used for testing the possibility of launching " Wurfkörper 42 " artillery rockets from U - boats . In cooperation with the commanding officer ' s brother Ernst Steinhoff of the Peenemünde Army Research Center , a rack of six rockets were mounted on deck , and were successfully launched while on the surface and while submerged up to a depth of . However , the rockets were not particularly accurate and the racks on the deck had a negative effect on the U - boat ' s underwater handling and performance , so the project was abandoned . The U - boat was attached to the 10th U - boat Flotilla for front - line service on 1 September 1943 . In that role she carried out four war patrols , two commanded by " Kptlt " . Steinhoff , and two by " Kptlt " . Fritz Schneewind , sinking five ships totalling and damaging one of . The U - boat was transferred to Japan on 16 September 1943 and served in the Imperial Japanese Navy as submarine " RO - 500 " until August 1945 when she surrendered to the Allies . Service history . 1st patrol . On 16 July 1942 " U - 511 " sailed from Kiel and across the Atlantic to the Caribbean Sea . At 06 : 29 on 27 August , " U - 511 " fired a spread of four torpedoes at Convoy TAW - 15 , en route from Trinidad to Key West , about south - south - east of Guantánamo Bay in Cuba , sinking two ships and damaging another . The 13 , 031 ton British tanker " San Fabian " , loaded with 18 , 000 tons of fuel oil , was hit and sunk . The master , 31 crewmen and one gunner were picked up by the destroyer and the patrol craft , 23 crew members and three gunners were lost . The 8 , 968 ton Dutch tanker " Rotterdam " , carrying 11 , 364 tons of gasoline was struck and immediately began to settle by the stern . The 37 survivors of her crew of 47 abandoned the ship in lifeboats and were picked up by . The 8 , 773 ton American tanker " Esso Aruba " , loaded with of diesel fuel and serving as the flagship of the convoy commodore , was hit by a single torpedo on the port side which badly damaged the ship , but left the engines and steering gear still operating . This allowed the ship , in danger of breaking in two , to proceed under her own power to Guantánamo Bay , arriving the next day . The ship was beached and her cargo unloaded . After temporary repairs the ship proceeded to Galveston , Texas , and was returned to service in February 1943 . The U - boat arrived at her new home port of Lorient in occupied France , on 29 September after a voyage lasting 76 days . 2nd patrol . " U - 511 " sailed from Lorient on 24 October 1942 , and patrolled the waters off the coast of north - west Africa before returning to base after 36 days , on 28 November , having had no successes . 3rd patrol . " U - 511 " , now under the command of " Oberleutnant zur See " Fritz Schneewind , left Lorient once more on 31 December 1942 to patrol the waters between Spain , the Canary Islands and the Azores . At 21 : 42 on 9 January 1943 she had her only success , sinking the 5 , 004 ton British merchant ship " William Wilberforce " , loaded with 5 , 054 tons of West African produce , including palm kernel s , palm oil and rubber en route from Lagos to Liverpool . The unescorted ship was torpedoed west of the Canary Islands , with the loss of three crewmen . The master , 41 crewmen , six gunners and 12 passengers were later picked up by the Spanish merchant ship " Monte Arnabal " . " U - 511 " returned to Lorient on 8 March after 68 days at sea . 4th patrol . " U - 511 " s final patrol took her all the way to Japan , as part of the ongoing programme of technological exchange . She had aboard additional personnel , including the German ambassador to Tokyo , the Japanese Naval Attaché in Berlin and German scientists and engineers . Leaving Lorient on 10 May 1943 under the command of the now " Kapitänleutnant " Fritz Schneewind , she sailed through the Atlantic and around the Cape of Good Hope into the Indian Ocean where she made two kills . The first attack was made at 09 : 42 on 27 June , when she hit the unescorted 7 , 194 ton American Liberty ship " Sebastian Cermeno " with two torpedoes , disabling the engines and killing an officer and two men . The survivors abandoned ship in five lifeboats . Ten minutes after being hit , the ship sank . The U - boat surfaced and questioned the survivors before leaving . The lifeboats lost contact with each other , but all were eventually rescued by Allied ships , apart from one boat which made its own way to Madagascar . Her second success came on 9 July when she torpedoed the 7 , 176 ton American Liberty ship " Samuel Heintzelman " , loaded with 5 , 644 tons of ammunition and general cargo . The U - boat dived after firing and did not directly observe the results , but heard underwater explosions . On surfacing they saw no trace of the ship , only floating debris . There were no survivors from the 75 men on board . The ship was reported missing , and was at first believed to have been sunk by a Japanese surface raider . On 30 September , wreckage from the ship was discovered off the Maldives . The U - boat arrived at Kure on 7 August after a voyage lasting 90 days . and was handed over to Japan on 16 September . Fate . The submarine was scuttled in the Gulf of Maizuru by the United States Navy on 30 April 1946 .