I started to miss by the bow after I upgraded the torpedo range/damage passive to max and after testing the torp speed went from 44kts to 52kts and you could determine that the TDC doesn't take this into account. OF course you can't notice it if you prefer shooting at close range.
I missed one peculiar thing also, as you assign the points the skill states clearly to torpedo range and damage, but by clicking the little arrow next to the torpedomans slide bar it states torpedo SPEED and damage.
There's a thread about this, link below:
http://www.subsim.com/radioroom/showthread.php?t=164360