About the book: 2006 / German specialists completed theoretical research in the field of electric submarine design in January 1943, just when Dennitz replaced Raeder as Commander-in-Chief of the Kriegsmarine. The calculated data of the boat was amazing. For 90 minutes, the submarine was capable of maintaining a speed of 18 knots, and for ten hours it could reach a speed of 12 knots, the cruising speed in a submerged position was 5 knots, and at this speed the boat could travel for 60 hours. The characteristics of the promising y-boat in comparison with the data of the VIIC boat looked fantastic. “Das ist fantastische,” he put his resolution. Karl Doenitz.