Yeah. The thing with SH3 is that it is designed as a submarine battle, not a surface battle. The AI can be really stupid in surface battle situations. Once I stayed behind a ship that was only properly armed in the bow. The stern had a low-range gun of some sorts. The ship was travelling in a two-ship convoy and never did leave it's formation to shoot me with the real stuff. I stayed out of the lowrange weapons range and could shoot the surface ships in impunity. ASW trawler if remember correctly. Anyways I started feeling really silly pretty soon.
I interrupted the attack and now go after the rule BdU actually gave during the war: U-boats are not allowed to attack armed vessels with the deck gun.