[Walruss]

If seas are good, and it's small (less than 5,000 GRT), then nothing beats sneaking up to about 1,500 meters and sneaking an 88 just below their water line. I'm still in '39, so if there's a good opp to save an eel, I always do.

Elsewise, no radar, surface attacks are the way to go.... Tried it in the middle of a convoy last night (see my convoy tactics question thread), worked an absolute charm.