AI is good. Destroyers will track the torpedo wake back to the sub...so dive dive dive after you have fired. Fortunately, the japanese poor ASW is your friend
). Destroyers will attack in pairs. One listening, the other one charging. They call aerial support if you are close to land, so beware. Do not try to torpedo a destroyer if you are more than 3-400 meters away. They see the torpedo and avoid it. This is just an example. AI is not crap at all...beware and do not underestimate the japs. Pilots are skillful, you won;t get away by making sudden turns at flank speed. Your gunners are poorer than in sh3. Add to this...a rusty S class bucket which dives safe only to 50 meters.....and you;re in big trouble.