Well, the reason I found this slight scale distortion is because I was actually trying to find a way to (ab-)use the Range/AOB finder scales to do the Length/time=speed calculation. Which I did, but marks that do not entirely match don't make that easy for me. So you don't really need to make a table for speedconversion IMHO. Only a small mark on the Basis-scale would help.
EDIT; Nov 6th 2007: I made a stupid mistake in understanding how the scopemark scale is constructed. I forgot it is based on the tangent formula. The mathematically correct 'speed'-mark is NOT 54 degrees as I initially thought, but the 58th degree on the AOB scale. However, because the scales in the earliest versions (incl. 1.1) of this mod are slightly distorted any speedreading between 60 and 54 degrees is a good ballpark measure.
So to use the Range/AOB finder as a speed calculator do the following:
1. Align shiplength on the Basis-scale with time in seconds on the Range-scale (so outer-midde ring, ignore range is in steps of hundred meters)
[older EDIT: removed old 3-step procedure to just 2. Easier and less prone to calculation error]
2. Read of the speed in knots above the 58th degree mark in the AOB scale. (should work upto speeds of 30 kts as that is the limit of that scale)
Whether or not this was done historically in WW2 I don't know. But a smart Kaleun sure could have figured this out just as I did. .... If he was a bit mathematically inclined.
(I'll try to include some screenshots in this post later. Don't have time now. Stay tuned. )