The U - 480

The U480 was, to all intents and purposes, the worlds first stealth submarine. When it was on patrol in the very dangerous English Channel, the British had no idea it was there, south of the Isle of Wight. But evidence of its presence was soon discovered when 4 ships including 2 warships, were torpedoed and sunk. Through intelligence work, the British discovered its patrol area and after secretly informing all channel shipping to avoid a given area, they laid deep mines in exactly the right place. The U480 returned from its base to assume patrolling but ran straight into the trap. A mine blew off the stern of the U Boat, causing tons of water to flood the submarine in seconds.
What was the secret that made this submarine virtually invisible to  sonar?  Rubber panels! They were laid on the surface of the submarine and had equi-distant holes in the fabric which actually absorbed sonar thereby rendfering the submaine invisible.

In August 1944, during the 2nd World War, four Allied ships are mysteriously destroyed without warning off the coast of Southern England. Sixty years later, in the English Channel, 20 kilometres south west of the Isle of Wight, 55 metres down, the sea reveals a 2nd World War German submarine unlike any found before. Using revolutionary investigative techniques, a team of underwater detectives discover a story of invention and heroism, and a secret stealth technology. Identified as U-480, it was the first U-boat to go into successful action with a special coating that made it invisible to sonar. But not even this could save the submarine from a fatal trap set by the Allies.

The WW2 archives had the submarine sunk much further west,  near the Scilly Isles. The actual sub sank was the U1208.  It is only recently that the truth came to light in a very clever Discovery documentary that virually drains away the seas by computer, showing the wrecks, as if they were sitting on a beach. U480 clearly shows the devastation rendered on the stern. A large section of the stern was completely broken away and lies on the sea bed just aft of the main body. The crew would have had no chance at 190 metres depth.

Commissioning 6th October 1943
Often described as an 'experimental Type 7' It really was just an ordinary type 7 but with the rubber cladding, nothing else was added to the original sub. Its Captain was Hans-Jorchim Forster. The sub was laid down on 8th December 1942, launched 14th August 1943 and commissioned 6 October 1943. Test depth was 750 feet. (230 meters).

Commissioning 6th October 1943
The submarines first operational patrol was 1 June 1944 to 29 October 1944 and the second, fatal, patrol was 15 October 1955 to 29 January 1945. I presume time in port did not count against patrols as there is only 24 hours between end patrol 1 and begin patrol 2.
Sunk on or after 29 January 1945 in the English Channel south-west of Portsmouth, in position 50.22N, 01.44W, by a mine in the British field Brazier D2. 48 dead (all hands lost).
U reports in general comments that U-480 was one of about ten German U-boats that were coated with rubber in an attempt to elude the Allied ASDIC and Sonar detection equipment. The coating process became known as Alberich. Apparently this worked quite well on this boat but overall this was troublesome as the rubber tended to peel off during passage.

British intelligence knew about this project early. However, amazingly enough there are no analyses by the Royal Navy during the war years 1944 and 1945 known yet, which have examined successful missions by “Alberich” U-boats and drawn conclusion from those. After all, as early as January 1944 the British have gained secured infor-mation from reports by agents or interrogation of U-boat crews in captivity about the trials with rubber coating of U-boats, but were not quite sure about the real purpose of this project. In November 1944 the British Admiral (Submarines) forwarded a summarizing report to the Secretary of the Admiralty about the knowledge gained so far on rubber coating of German U-boats, concluding, that, with high probability, it must be a technical measure to protect from ASDIC detection. Therefore, not without some reason behind it, the British and the Americans have decided very quickly at the end of the war, to keep U 1105, the famous “Black Panther”, which had surrendered to the Allies in May 1945, from the list of U-boats to be scuttled. Rather, to examine it thoroughly and execute, if deemed necessary, further tests and trials. U 1105 was scuttled by the US Navy in Chesapeake Bay off Virginia as late as 18 November 1948.  Taken from: