One of the most important aspects of a deep simulator is the ability to override the automation of certain systems and have full control over all settings. In a U-boat, the power-plant is arguably the most important system; it moves the boat, and charges (or discharges) batteries, blows ballast tanks when surfaced etc.. . Without the power-plant, the U-boat is useless.
In order to simulate an accurate and fun system, I have pulled specs from the VIIC manual. The main powerplant layout includes two banks of motors, engines, 2 clutches, and the propeller itself.