[XenonSurf]

Harpoons or TSMs are really easy, it doesn't matter where you aim, it's only important that they don't overshoot the target, their seeker will easily find anything ahead of their PAP, and the missiles have enough fuel. Warships may however shoot them down. So these missiles are not a problem.

Sea Lance missiles are very tricky to calculate the right waypoint setting, I usually aim a little ahead of the aid marker to be sure the torpedos splash *in front* of the enemy, that's where it's the hardest to make evasion.

For torpedos it's true that the aid marker is not accurate for targets that head away from you, try to remember the run-out time as soon as you launch one , this should aid you in your calculation to know wether you can reach a target.
Usually enemy subs are travelling at 15 knots when not detected, so count 40-15= 25 knots true catch-up speed and see if the run-out time is enough. Because I don't have the exact formula that tells me that '1 minute at x knots = y kyds', I'm using guessing work based on the initial distance. Something like 1/2 of the max torpedo range (15-17 kyds) should be fine.

But the max torpedo distance is rather useless in CW because I'm never able to detect any sub at 30 kyds or so, only about 10-15 kyds if he cavitates or if I have the perfect aspect angle to him at the same depth. So torpedo ranges should never be a factor in the game. If you fire one at a distant sub 15 kyds, you may not reach target with MK-48 if he heads straight away from you, otherwise it will arrive and have about 2-5 minutes remaining for the kill.
Activated MK-48 will travel around 60 knots instead of 40, so for less than 15 kyds they may actually have an increased range before burning out. Problem is at such a speed they will be detected earlier.