I used that GUI in the past but then I moved to the ACM Reloaded GUI (
http://www.subsim.com/radioroom/show...=155366&page=7) It succeeds OLC GUI.
-Anyway, the way I intercept enemy contacts is first by going to the bridge (or periscope if submerged) and making an observation (Range and Bearing) then marking it on my map.
-Around an hour later I take another Observation, again marking it on my map.
-Then I connect the marks, measuring the distance it traveled in that hour which I can later use to determine speed, but that line also shows you the ships bearing which you can use to intercept at a 90 degree angle.
Using that method, I can usually get within 500m of where the ship is supposed to be headed, even if it is like 8 miles away (any further and I can't really obtain viable observations.)