5th patrol now (I think - have to insert an agent at Liverpool - WTF is Karl thinking
) and have only used manual TDC.
Added to that I've used no other assistance other than the mark-1 eyeball and the bow wave size to determine speed - getting down to a fine art +- 1 knot.
The sound guy gives you the speed range,, and from there it's keen observation.
That and getting close as possible to avoid error propagation.. total tonnage = 189633 (25 ships). I'd say I'm getting a 75% strike rate.
Maybe I should do a longgggg video..