In the documentary "Battle of the Atlantic" I think it was his WO interviewed.
He said something along the lines of 'My captain
Otto Kretschmer was a very intelligent man, and very cold blodded."
Ok well Otto Kretschmer was the Man.
Just thinkiing the whole Das Boot ram & jam deal doesn't gear well in the game. Past `40 at least. It's fun though, watching merchants scatter & try to ram. Untill they start shooting back.