Nice to see someone else finding that they can send bearing without using the stadimeter. I would add that the more techniques you add to your manual targeting bag of tricks, the more successful you will be.
You can dispense with even more of the TDC funcions by using the Dick O'Kane technique, setting up an attack course of 90º from the target's course. Then all you need is the speed of the target and your torpedo speed to determine your lead angle on the target.
You don't want to deal with the math or a chart? No problem! Just enter the target speed into the TDC and sight right on the target. With the PK turned off, angle on the bow set to 90º (make sure the target's bow on the TDC is pointed in the correct direction!!!!), when the target hits the crosshairs, press the range/bearing send to TDC button and shoot as often as you think necessary as the juicy parts of the ship pass the crosshairs.
Now even range doesn't matter! You should shoot sometime between bearing 10º and 350º, another 5º either way isn't fatal (well, it IS fatal to the target, but who's going to object to that?
). Being 800 yards or closer to the target is recommended, although anything under 1200 is pretty much guaranteed hits.
There are several techniques to be used. Make sure you learn conventional targeting using that stadimeter for the times when you can't properly set up your attack and need to get a decently aimed shot off anyway. WernerSobe attack school will take care of that. With a well-rounded bag of tricks you can take stock of your situation, choose the best-fitting technique and bag your target.
Keep practicing on Werner's sonar technique. It's deadly once you get proficient. Great in the middle of the night when you find yourself in the middle of a convoy and can't even see the ships for identification! Remember that they can see you in those conditions because the Japanese used infared field glasses. They have 'em in the game too, so don't get overconfident in blackout conditions.
Good luck! Subsim is the best place to learn how to master this game.