Thanks guys.
I wish i had the XXI now,

oh well i'll have to brave another few months out at sea, ive notice now i cannot even get near a convoy the destroyers know im out there the closest i got in last patrol was 3800yds submerged, running at 3 knots, 3 destroyers heading towards me range about 2000yrds and closing, I fired all forward torpedos and did a 180 turn, went deep and got the hell out of there. Sunk 1 liberty cargo which was a fluke as i just randomly fired into the convoy. Even still i was depth charge forward topedo room destroyed, all scopes destroyed, sonar destroyed, still had a plenty of torpedos left but limped home instead.