its a sticky over on the mods section of the forum....
the Schnell boot mod replaces the Type IIA with a Schnell boot fully operational with 3 AA guns and 4 torpedoes
Dash in on targets at up to 40 knots, and when the destroyers become aware that you have made your attack - speed away as they try to retaliate with their shells flying past you and you outrun them from the scene.
