Characteristics
| Crew | 57 mens |
| Length | 76,7 m |
| Max speed (surfaced) | 15,6 noeuds |
| Max speed (submerged) | 16,8 noeuds |
| Range (surfaces) | 15500 miles nautiques |
| Range (submerged) | 56 miles nautiques |
| Max tested depth | 500 m |
| Tubes | 6 |
| Torpedoes | 24 |
| Guns | Four 20 mm guns |
| Production | 119 |
History
Before the beginning of the war, professor Walter and "Germania Werft" shipyard worked on th project of submarine working with oxygenated water in order to built a submarine being able to function without the oxygen of the air. The uboat would not have to surface regularly to recharge cells.
Several projects of this type will end to the construction of the experimental of type XVII and XVIII. Nevertheless, those types were not massively produced because of three huge weaknesses:
* For the price of one type XVIII, it was possible to build two type VIIC.
* The fuel consumption was too high.
* The quantity of oxygenated water for these U-boats would necessitate the construction of new facility to produce the fuel.
The typical XVIII is therefore transformed and equipped withdiesel engines. It becomes the type XXI, the most advanced submarineof the world war two.It is able ton attack its preys without having to approach the surface. In addition, the hydraulic loading system of torpedoes allows the loading of the six tubes within 12 minutes while this operation on a typical VIIC asked 10 to 20 minutes for an alone tube.
The first type XXI submarine was launched on May 12, 1944 and commissionned in June 27.