Deviation

The deviation table shows the compass error (deviation) for any steered course. The table is the standard deviation table from "Yachtskipper af 3. grad" (Watergames). Deviation is interpolated linearly — the same method used in the course conversion tables and My route. Because the deviation table describes how the vessel's own magnetic field affects the compass, it only applies to that particular vessel and compass. If you are logged in, you can enter your own table under My account, which is then used throughout the app (here too).