Method I use is to drive my boat at flank speed directly toward the target. If the target drifts to my right then her course is towards my right, and likewise if target drifts to the left then she is heading to my left. Once you know which direction the target is heading turn your boat 60 degrees in that direction and you will be on an approximate intercept course (this is called the approach phase). Once ahead of the target and normally submerged you then take the range, speed and AOB to fine tune your position and set up the torpedos (called the attack phase). Got this tip from a fleet boat manual, posted in a Rockin Robbins (
) thread here:
http://www.subsim.com/radioroom/showthread.php?t=146795 Hope this helps.