I sunk a few loners off the Western tip of Ireland. Somewhere in early 1943. Those were lucky encounters 'cause they were tilting full speed (25+ knts).
I managed to spot one inside a convoy in '42. I was unable to get a hit on it because the convoy was defended by 8 dd's that kept harassing me.
My game is an almost clean 1.4 install with only some minor graphic tweeks....
A while ago when I had world mod 2 installed, I turned the Western Approaches into a graveyard for passenger liners: too much of them!
Although I have been lucky enough to have found some passenger liners, I have never spotted a juicy Task Force....
I guess luck is a big factor in this fine game!