Some good info - thanks all
Watched the vid then checked out and tested the clicks
As you can see I know the range to target is 720m
I know mastheight is 40.4
The 90deg mark shows that the mast should be 2.25 clicks not 6.75
Ok in this one I match range to ship lenght (111m)
5.5 clicks on the bow should be 64deg AOB
Actual was 70 deg and should be 5.75 clicks.
Both pics at at 1.5 zoom.
I will read and test the link from TDW next.