I target my torpedoes only manually, but I think I know were your problem is: try to avoid aiming at big angles. Watch your torpedo bearing indicator - it should be the best at 0 degress when you fire, it could be as well at range from 340 to 20 degrees, but rather not less nor more. If shooting aft torps, the values are from 160 to 200 degrees. The bigger the degree and the torpedo the more likely to miss.
Rules of thumb are:
- try to keep your torpedo bearing less than 20 degrees from bearing 0 and 180, respectively,
- never shoot when the angle would be more than 90 degrees.
Later in the war the torpedoes are said to be able to go even at 120 deg. angle, but I don't believe their mechanisms that much...
PS And welcome among us! Remember to drink, eat and have a nice company before you leave to patrol. Like all of us, you are most likely not to come back home never more... Till the next one.