[Heibges]

Determine target course.

Set your uboat on the same course, and determine the target speed using the matching speed method.

Enter target speed into the TDC.

Calculate attack position and Firing Point.

Conduct overhaul manuever.

Get on 90° Attack Course with target. Basically, based on targets know course, make sure your final course adjustment before launching torpedoes puts you on a perpendicular approach to the target. Remember, do not confuse the 90° Attack Course with 90° AOB.

If the target is moving left to right the AOB will be Starboard.
If the target is moving right to left the AOB will be Starboard.

I fire with 10° of lead on targets 1200m and under. So I fire when the target is bearing 10° (right to left targets), or 350° (left to right targets). Because I am on a perpendicular course to the course of the target I know the AOB at that position.

For targets over 1200m I fire with 20° of lead at bearing 20° and 340°.

Right to Left Target
Bearing 10° = AOB 80° Port
Bearing 20° = AOB 70° Port

Left to Right Target
Bearing 350° = AOB 80° Starboard
Bearing 340° = AOB 70° Starboard

Remember, the above is true if and only if you are on a perpendicular course to the course of your target.

So I am know 10,000m from my target and I already know AOB and Speed.

Finally, I determine range. This will be my final correction to the TDC before firing.

I use the MILS method to determine range, by measuring the length of the ship.

Here is an exerpt from my range chart

Target..........1200m..........1000m......800m.... ..600m
C2.................6..................8........... .10..........12
C3.................7..................9........... .11..........14

This will give you almost instantaneous range, and is more heavy weather friendly. Like everything else, this works best when approaching at the 90° angle.