I can not say for certain myself but from what I've read about h.sie's wolfpacks in his hardcode realism fixes mod, and from what I've seen from the test mission included in the mod, the AI subs(five I believe) are on the surface and attack using their deck guns. The escorts and convoy will react to that-firing starshells, returning fire, zig-zagging, etc.
Key thing to remember is that it is a "design for effect", not a "realism effect". The AI wolfpack subs will disrupt he convoy, opening holes up in the escort screen for you, the human player, to exploit and to damage other ships in the convoy so that you may have an opportunity to finish off.
I would think that timing is everything. If you are in the wrong place at the wrong time, you may not be able to exploit it, just as in real life.
Like I said, I may be blowing sunshine out my butt
and completely wrong though. I have the mod enabled and have not had the pleasure of seeing the wolfpack in action in a career. I've always been released to attack independently after an hour or two of shadowing the convoy. That alone makes the game more interesting. Now, instead of attacking the convoy whenever you feel like it, you have to at least gather information on the convoy, radio in a contact report hourly, and await an answer from BdU. I've expereinced that portion a few times in a career.
I'm jealous that you were able to see it in action in a career.
Even without wolfpacks enabled in the hardcode fixes by h.sie and Stiebler, the work they have done is incredible. It has breathed so much fresh air into SH3 that it makes it a joy to keep coming back to it time and time again.
They and all modders deserve a huge thank you for all the work that they do.
