Hello,
steve51!
I'll be brief:
If you'll tick-out all the realism settings, you'll have your game almost with cheats:
Your fuel won't deplete, so you can always go on flank speed and round convoys.
Your sensors will be much better then your enemies' and you will find them sooner and can plot your course to get very close.
With automatic targeting system - it's much easier. You only have to lock the periscope on enemy and enable TDC updating (don't remember, how it's on English).
Same is for map contacts update.
You can download Webster's improved torpedos, so you'll sink almost every merchant from one torpedo.
The point is.... If you want cheats for some other aspects of the game... there will be not much gameplay actually for you to play! You'll get bored!
So bring realism to 0 and try like this.
Best regards