B&G Deckman - Manual (Page 122)

NMEA Instrument System
7.17
The heel maximum should be set to a value which is the maximum you
would expect to see when sailing.
The leeway calculation is a function of angle of heel and the square of
the boat speed: you will have to experiment with it to get the right
values for the calibration, but expect a figure between 5 and 7.
The final value is for damping of the true wind direction. You should be
able to use a value of one in light weather—no damping—but you may
need more in heavy weather.
Note. It is important that the instrument system boat speed is calibrated
correctly because Deckman corrections have no effect when the yacht is
upright, as when sailing downwind.
Note. Do not expect the calibrations here to give you a perfect true wind
direction that is consistent through tacks: you will still probably need to
use the special true wind calibration tables which are described in the
next chapter.