53 50_Afficheur_Multigraphic_um_UK_27
Course
Heading
Press “OK” to save the new correction. You can highlight “Abort” and press “OK” if
you want to cancel a correction. Repeat this operation every 30° to fill the whole
correction table. The compass will have its deviation curve implemented once this
table is completed.
2.8.3 Drift angle
Drift angle is measured between the boat’s heading and its course.
This value is used for true wind, VMG, corrected heading and current calculation.
Therefore it must be calculated optimally.
We use the following formula:
The correction factor is linked to the hull shape and the boat’s performance. Lower
values indicate higher performance The drift value is always applied whatever the
navigation conditions. Therefore, it has to be an average value, valid for all weather
conditions or alternatively, you can alter that value upon the wind strength.
The drift angle for each boat speed and heel angle is shown with the polar tables
supplied by your architect. Calculate the drift factors with the formula below, and
determine the average value.
Use a 10.0 factor if you cannot find the relevant data.
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