I'm with rfunes on this. I just (and I mean only just by the skin of my teeth), finished my first Bergen patrol in early '43. From about 100km off the Norway coast I was detecting radar signals of aircraft and DD's. One lucky night I picked up a task force and managed to sink HMS Victorious

, but from then on my trip was aircarft nightmare. I think I managed to spend about 2-3 hours per day game time on the surface on my way to patrol grid AM47.
As I got to within 80km of my patrol area two Sunderlands jumped me and knocked outboth periscopes, my radar, radio and radar detector. There was also a whole stack of hull damage and batteries etc. were out for a while, so the damage control was a world of pain for about half an hour real time.
After spending the next 6 hours underwater U754 limped back home by going way north of Torshaven and back to Bergen with only two more ships sunk and 6 torps in the boat.
Love this game and GWX has just made it ever more fun than ever.