I actually don't use any tools for figuring AOB. The way I do it is to imagine I am standing on the target ship looking at my submarine. The direction I have to face to see my submarine is the angle on the bow.
For my initial shot I always try to set it up for 90 degree track and 0 gyro angle for my torpedo. Let's assume that the target will crossing in front of us from left to right. Well before I am in shooting position I set my TDC by putting my scope/uzo on 0 degrees. I then set the AOB to 90 degrees starboard and lock it in (hit the button). After that--as long as I am approaching the target track at 90 degrees--which ever direction I aim will change the AOB correctly. IE--if the target is 30 degrees to port hid AOB will show as 60 degrees starboard. I then wait until my torpedo track will be 0 degrees and fire as he crosses that bearing. That bearing will be dependent on the speed of the target and my torpedo speed setting.
In the case of firing at multiple targets (a convoy) I shoot at my farthest chosen target first. That shot is usually NOT the one that will have a 0 gyro angle for my torpedo. However, if I am at 90 degrees to the course of the targets, I never have to change the AOB manually. It is already locked in. It even works when I switch my view angle to fire from the stern.
Once used to this method, it easily possible to have all your torpedos in the water before the first one hits. If a convoy is alert and zigging, I simply redice the target speed on the TDC by 1 knot to compensate for its maneuvering. If I'm within ~1200 meters that usually works although those are the shots I am most likely to miss.
IMO--the trick is to set all the angles well before it is time to shoot and then maneuver into the correct position (90 degree track). In the patrol I ran last night in my IXB I sank 11 ships by torpedo (only 1 was over 5000 tons though
). Using this method I am able to shoot at targets 3000 meters away with good success although I prefer to fire at 2000 meters or less.
Hope this helps!
