B&G Zeus2 Glass Helm CPU - Manual (Page 43)

Magnetic variation
Magnetic variation is the difference between true bearings and magnetic bearings, caused
by different locations of the Geographic and the Magnetic north poles. Any local anomalies
such as iron deposits might also affect the magnetic bearings.
When set to Auto, the system automatically converts magnetic north to true north. Select
manual mode if you need to enter your own local magnetic variation.
Datum
Most paper charts are made in the WGS84 format, which also is used by the Zeus 2 Glass
Helm system.
If your paper charts are in a different format, you can change the datum settings accordingly
to match your paper charts.
Coordinate system
Several coordinate systems can be used to control the format for lat./lon coordinates
displayed on the chart panel.
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