If you're out of torps, DO NOT make the mistake I did and, feeling unable to fight back, surface to fight it out with the deck gun... That's the short way to the bottom. I found out one day when feeling reckless...
You might want to remember that the DDs are armoured - I forgot - and that they've got lots of big guns whereas you've got a 20mm flak peashooter - which I also forgot.
I was back on the bottom within 3 minutes of surfacing to duel it out.
(I'd like to think that, had it been real, I could have surrendered.)