Actually the Ship damage has been adjusted it seems. Looks better. The holes look better. Pretty explosions some times... Ship sinking seems to be random to me.
I lost 3 kills my last long ass patrol because the ships would not sink and just kept going. Now most of them only had 2 hits... But one I hit with a 3rd and it still did not go down.
At that time I didn't know that the Destroyer AI was broken so I ran away before I got spotted.
If I would of known the Destroyer AI does nothing at that time I would of waited and finished them off.