Here's an example of how it all works: Submerged, daylight torpedo attack.
I've spotted a small convoy on my port bow, heading east. I adjust my course and/or speed to get into a collision course with the medium merchant (c2), so that it's bearing is constant:
My Course = 006° True...
The target ship's AOB appears to be about 30° starboard...
I then apply the information to my combination "whiz-wheel"...
My "whiz-wheel" consists of 3 layered wheels.
The Large wheel represents TRUE Compass.
The Middle wheel represents the Submarine.
The Small wheel represents the Target.
Now that I know the target's Bearing and AOB, they point to the target's TRUE Course of 095°.
I need to compute the target's speed to complete my firing solution, so I flip the whiz-wheel to the opposite side and use the circular slide rule.
After plugging the info into the vorhaltrectner/TDC, I slow the boat to 1 kn. and wait for the target to reach about 70° AOB before pulling the trigger.
I might add here, that I never worry about RANGE.
Something I learned in the ACADEMY is, if the target (see above) fills 1/3 of the viewfinder in x1.5...you are within 1000m. So, whenever you get a sight picture like that (NO MATTER THE WEATHER)...you are close enough to kill.
Hope this made sense.
cheers,