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Chapter 7: Setting Up the System Defaults 7-21
Position Offset
CAUTION:
Changing the chart datum does not cause any waypoint or routes stored
in the chartplotter to move on the display, although their latitude and
longitude changes to reflect the new datum.
When adding waypoints numerically to the waypoint list, or via
SeaTalk,NMEA or
hsb
2
, it is important that they are referenced to the
same datum to which the display is currently set.
When you change datum selection, the system attempts to set any connected
GPS to the new mode, using SeaTalk and NMEA set up commands. A
message shows whether the set up was successful or not.
Position Offset
You can offset the vessel position to allow for differences between the GPS
and paper chart data. This may be useful if you are using a datum that is not
available on the Chartplotter, or if you are referring to a paper chart drawn to
unknown datum.
You can change the offset by moving the cursor to the known vessel position.
This offset is applied to all incoming position data. The default offset value is
zero.
When position offset is switched on, all displayed vessel position data is
annotated (C) to indicate it has been corrected.
➤ To switch the position offset on/off:
1. Select the POSITION OFFSET option, then press the OFFSET OFF ON soft key
to toggle the option on/off. The last selected offset value is added to posi-
tion data and the vessel is displayed at the corrected position.
➤ Tosetanewoffsetvalue:
1. Select the POSITION OFFSET option, then press the SET UP OFFSET soft key.
If necessary, position offset is automatically toggled on.
2. Usethetrackpadto movethe cursorto therequiredvesselposition; the cur-
sor position is displayed in a position offset data box.
3. Press the ACCEPT OFFSET soft key, the vessel is displayed at the new posi-
tion. Press ENTER to return to the default display.
➤ To set the offset value to zero:
1. Select the POSITION OFFSET option, then press the SET UP OFFSET soft key
2. Press the CANCEL OFFSET soft key. The position offset value is set to zero.
81186_3.book Page 21 Thursday, August 22, 2002 8:23 AM