exciting story!
just one remark:
I try to stay away from the lead-escort at least 1,000-1,500m. the chances of being detected are quite low at this range. creeping at 2kn at a perpendicular course to the convoy's bearing will get you in a fine position. you either can surface amidst the convoy (early at war and in poor visability) or shoot all your 6eels submerged.
when the explosions are then all around you, the escorts seem to be puzzled where to look for you and you can safely escape at 160m .....
just my 2€-cents
