this wasnt me but my dad ( the one who bought the game and got me hooked
) anyways after he missed with a torpedo(against a flower 'vette he surfaced and shot at it with you guessed, his flak gun (fyi it was behind him[He had shot a aft torpedo]) anyways it caught up and hit him from the back and pushed him at about 10 knots for a couple minutes before it broke off and slid along his side (with my dad going full auto on his flak gun lol) , at this point the flower pulls ahead and turned and he pulled his uboat around to chase him and finished him off with his deck gun :p