manual targeting (yes, it's hard)

[Bosje]

Good morning, excentric and expert friend and fellow Kaleuns

I am in base after Freiherr Beckman's second patrol (first feindfahrt after a shakedown) in late 1942, the idea being a new war journal detailing The Duke's adventures on a 100% realism career.

For this, I'm using GWX 2.0 and SH3 Commander with map updates ON (showing the contacts on the map without any further details.

So this requires manual targeting without weopon officer assistance.

On the feindfahrt I sank some 25.000 tons including a very lucky shot on a light cruiser at 15knots but I am not yet fully understanding it all so here are my questions:

-Is it possible to do the targeting partly through the notebook and partly though manual override input?
I manage to get the range right in calm weather through the stadimeter and the AoB is easily calculated from the chart but the speed is always wrong so I input that manually after having set up the rest. As soon as i put the speed in, it seems the torpedo stops tracking.
So i need to fire immediately after correcting the speed?

even on mirror seas with a lone merchant steaming across my bow at 1kilometer, the torpedo does not hit where I want it to.

I'm running a new career starting 1939 just to practise, as in 1942 it's terribly hard to do the calculations in between all the escorts and airplanes but I'm still having trouble.

reading all the manuals and forum topics but I'm still not grasping this
any ideas?