Thanks for all of your responses, but I would like to clear up one small point;
I would never, ever, intentionally surface my boat to engage a warship of any kind, I know that would be like taking a knife to a gun fight. My thoughts were, that in the event, I were forced to surface, or could not submerge, because of damage, (flooding from depth charge attacks, etc), with a few AP rounds on board we could at least go down fighting, maybe even give 'em a bloody nose.
Fido