Like krauter said, with the torp shots, a 90 degree shot is the best. I dont play Sh5 and I dont use manual, but I always plot the targets course using the 3:15 method
(Mark the target, wait for 3 minutes 15 seconds, mark again, then draw a line straight through from the first mark to the next, the distance is his speed, .9 would me 9 knots, and it gives you his course, which allows you to go ahead and set up ahead of him at a perfect 90 degree shot (so you alreay know the AoB) and at a set distance so you already know that too!)
Using this method I find it incredibley easy to hit and sink targets, even in convoys and such!
Hope that helps
Casey