Are you using O'kanes constant bearing technique?
You calculate the firing bearing for a zero gyro angle shot based upon target speed and torpedo speed.
For example, the firing bearing for a 29 knot electric torpedo on a 12 knot target is 22.4 degrees.
If this is the method you are using you must calculate the firing bearing from accurate data.
Target speed and torpedo speed.
Steam torpedoes in US boats are 46 knots in high speed (the only speed I use since I shoot from less than 1000 yards) Electrics are 29 knots.
You calculate the firing bearing by finding the Arctangent of the target speed divided by the torpedo speed.
Set the AOB to 90 to 110 but dont touch anything else. Your gyro angle should be zero. Fire when the part of the ship you want to target touches the wire.
Doors should be open but I did work out the math for firing accurately with doors closed. It can be done accurately if you are concerned the doors opening will give you away.
All the math is in a spreadsheet I keep handy.
Wikipedia has a great chart but it only applies to 46 knot torpedoes.
If you are missing aft, your target speed is wrong or torpedo speed or the doors are shut or your firing bearing is wrong.
https://en.wikipedia.org/wiki/Torped...ctionAngle.png