When it turned out that the XXI boats were too large and expensive for use in the Western Approaches, the Kiel family company saw the opportunity for a "Walter U-boat" again and on October 12, 1943, presented a concept with the designation XXVIA.

On March 28 of the following year, the Commander-in-Chief of the Navy, Karl Dönitz, decided to have the boat built under the type designation XXVIW (for Walter).

[1] Type XXVI was designed as a deep-sea submarine with Walter propulsion, which should accelerate it to an underwater speed of 43 km/h (27 mph).

[3] For this reason, the Type XXVI was designed with six side torpedo tubes, which were located at the level of the command room, and were directed at an angle to the rear.

The amount of crude steel required for the hundred boats was estimated at 46,240 t. On August 27 of the same year, the order was accepted by the Blohm + Voss shipyard.