On the off chance that you haven't seen this:
I'm using the "U boat killer AI mod"
http://www.subsim.com/radioroom/showthread.php?t=165886
It's early on in the war for me '39 but this mod really makes a difference. The DD's will actually search for you (not always in the right area) and it makes the game so much more enjoyable. They are still pretty clueless but as I say, it's early days yet and the author of the mod seems to think that they will improve as we get later into the war.