Raymarine e7 User Reference page 307

Menu item
Manual Variation
System Datum
Customizing your display
Description
When the Variation Source menu item is set to Manual (see
above), you use the Manual Variation setting to specify the
compensation value that you want to use.
In order for your GPS receiver and multifunction display to
correlate accurately with your paper charts, they must be using
the same datum.
The default datum for your multifunction display is WGS1984. If
this is not the datum used by your paper charts, you can change
the datum used by your multifunction display.
When you change the datum for your multifunction display, the
chart grid will subsequently move according to the new datum,
and the latitude / longitude of the cartographic features will also
change accordingly. Your multifunction display will attempt to set
up any GPS receiver to the new datum, as follows:
• The internal GPS receiver will automatically correlate each
time you change the datum.
• If you have a Raymarine GPS receiver using SeaTalk or
SeaTalk ng , it will automatically correlate each time you change
the datum on the multifunction display.
• If you have a Raymarine GPS receiver using NMEA 0183, or
a third-party GPS receiver, you must correlate it separately.
It may be possible to use your multifunction display to correlate
an NMEA 0183 GPS receiver. From the homescreen go to
Set-up > System settings > GPS Set-up > View Satellite
Status. If the datum version is displayed, it may be possible
to change it. From the homescreen go to Set-up > System
settings > Data Sources > GPS Datum.
Note: Raymarine recommends that you check the displayed
vessel position in the chart application against your actual
proximity to a known charted object. A typical GPS has an
accuracy of between 5 and 15 m.
Options
• Range: 0 to 30 degrees, East or West
•
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