Hi Compadre, in uboat mission there are way too many task forces if you have map contacts turned on. Or if you mean the stock game with RSRD, then my limited 2 cents will be to hunt for the major events. there's some timeline here you can check for pacific war events -
http://www.historyplace.com/unitedst...r/timeline.htm
specifically, if you just start off your career, try to patrol around the wake islands first when the jap invasion began (around dec 23, 1941 i think). there are heck lot of TFs in that area. I had multiple successful interceptions there.
Other good places to hunt for TFs will be during like Midway battle, etc..I once encountered a huge convoy of more than 50 ships (mostly merchants) in the battle of java sea...a buffet I can never finish..
anyways, GL hunting kaleun.