Two questions concerning targeting/ torpedo control using manual TDC

[Crannogman]

Originally Posted by TorpX

I based my statement about the hash marks on CapnScurvy's exhaustive work on manual targeting accuracy with the stadimeter and telemeter marks. It is worth delving into, if you plan on using the telemeter marks.

Yes, I mentioned parallax error. And I assume that Spraug knows the fish and tubes displace the torpedo track forward/backwards from the scope.

It is a myth that one must shoot targets "dead ahead" to obtain success. This is neither true in real-life, nor in this game. Really, the development of the USN's TDC, to say nothing of torpedoes that could turn, would have been wasted effort, if that were the case.
There are alternate methods, apart from the "Dick O'Kane method" that do not rely on the game TDC's calculations, like THIS, for instance.

I found a lot of stuff about omnimeters and optical correction mods. Is this what you meant by Capn Scurvy's work?

Knowing the length of your parallax baseline (the distance from your scope to the point where the toro completes its turn) helps when you are shooting at higher angles, especially if you are setting your range at 11000y, because the torpedo will travel up to a hundred yards parallel to your sighting. Whereas, if you give it a range, the torp should be on a course that intersects close to that range.

Glad you got the help you needed.