In SH4 the PK updates the TDC parameters: range, AoB, torpedo track, not the periscope. In SH3 it is assumed you are doing a fast-90 approach. In SH4 the TDC works with any configuration of own and target tracks! This amazing advantage allowed you to set up a solution no matter what your relationship to the target is.
I recommend that you attend WernerSobe's Advanced School of Submarine Attack Tactics in his stickied thread above and follow the links I have previously posted in this thread when I was merely "arguing" to attend his amazing tutorials. Then my seminar on the Dick O'Kane attack procedure is available on page 5 (I think. Might be 4) for you to see what you can do if you turn the blasted PK off. Actually, subsequent experience and Arronblood's input have introduced some refinements, but they are not necessary to hit the target and so I have left the tutorial as is. I may make a new tutorial at some time but would leave the old one in place. It may be more instructive anyway as I got itchy trigger fingers and blew the attack, although all torpedoes hit and the target went down. See if you can spot the errors!
I will tell you that electing never to use the PK is just as crippling as deciding always to use the PK. A variety of attack techniques leads to greater success and the American submarine has a versitility the U-Boat cannot dream of. Results of my testing procedures:
The two planes were from when I was young and stupid. Don't shoot at those...