So the software allows one to input an adjustment table for windspeed at various windspeeds based on 180 deg downwind, and the computer then uses true wind angle to factor in how much of that adjustment to use. There is also the option to input a second table for adjustment of true wind angle, with rows for upwind, reaching and downwind and columns for wind speed. They suggest spending a day comparing tacking angles at various windspeeds. With the complexity of variable current and fluctuating wind, it will be challenging to get reliable data from personal observation. I'm having enough trouble getting boat speed right with my paddlewheel sensor adjustments, ha ha.
It looks like the previous owner left both those tables blank. What did you find on your boats?