U 2540 U-Boot Type XXI to Wilhelm Bauer
German "Electric Boat" Submarine

Type XXI submarines were a class of German diesel–electric Elektroboot (German: "electric boat") submarines designed during the Second World War.
One hundred and eighteen were completed, with four being combat-ready. During the war, only two were put into active service and went on patrols, but these were not used in combat.
The Type XX1 is truly one of the great submarine designs. The construction methods for this boat also broke new ground. Type XXI was constructed in ten separate sections, which were then delivered to the shipyard for them to complete, all except for the third section which had to be fitted with the diesel engines.

Wilhelm Bauer (originally designated U-2540) is a Type XXI U-boat of Nazi Germany's navy (Kriegsmarine), completed shortly before the end of World War II.
The U2540 was sunk in an air raid towards the end of the War, having never gone on patrol.
In 1957, it was raised from the seabed off Flensburg Firth, refurbished and recommissioned for use by the West-German Bundesmarine in 1960.
Finally retired fully in 1983, it is the only floating example of a Type XXI U-boat.
It has been modified to appear in wartime configuration and in 1983 the Wilhelm Bauer was made into a museum exhibit at the German Maritime Museum at Bremahaven.

This project involves three ships across the time axis:
U-2540 - Class of German diesel-electric Elektroboot;
Type XXI with Interior (open Structure of the Ship);
Wilhelm Bauer - 1 September 1960 until 28 August 1968 as a test boat (class 241).