Chapter 7: Setting Up the System Defaults 7-21
Datum Selection
YoucanselecteitherWGS 84 orLOCAL datum. In LOCAL mode,youare
presentedwith alistofdatums;use thetrackpadto scrollthroughthelist,then
pressENTER to selectthe optionandclosethe menu.
CAUTION:
Changingthechart datum does not causeanywaypointorroutesstored
inthechartplotter to moveonthedisplay,althoughtheirlatitudeand
longitudechangestoreflectthenewdatum.
Whenaddingwaypointsnumericallyto thewaypointlist,orvia
SeaTalk,NMEA or
hsb
2
,it isimportantthattheyarereferencedtothe
samedatum to whichthedisplayiscurrentlyset.
Whenyou change datum selection,the systemattemptstosetanyconnected
GPStothe new mode, using SeaTalkand NMEA set up commands. A
messageshows whethertheset up was successfulornot.
Position Offset
Youcanoffset the vesselpositiontoallowfor differences between the GPS
andpaper chartdata.This may be usefulifyouareusing a datum thatisnot
available onthe Chartplotter, orifyou are referringto a paperchartdrawn to
unknowndatum.
You can changethe offsetby moving the cursortotheknown vesselposition.
Thisoffsetis appliedto all incomingpositiondata.The defaultoffset valueis
zero.
Whenpositionoffset isswitched on, alldisplayedvesselpositiondata is
annotated(C) toindicateit has been corrected.
➤ To switch the position offset on/off:
1. SelectthePOSITION OFFSET option,thenpressthe OFFSET OFF ON soft key
totogglethe optionon/off.The lastselectedoffset value is added to posi-
tiondata andthevesselis displayedat the correctedposition.
➤ Tosetanewoffsetvalue:
1. SelectthePOSITION OFFSET option, thenpresstheSET UP OFFSET soft key.
Ifnecessary,positionoffset is automatically toggled on.
2. Usethetrackpadtomovethecursortotherequiredvesselposition;thecur-
sorposition is displayedin a positionoffsetdatabox.
3. Pressthe ACCEPT OFFSET soft key, thevesselis displayedat the new posi-
tion.Press ENTER to returntothedefaultdisplay.
➤ To settheoffsetvaluetozero:
1. SelectthePOSITION OFFSET option, thenpresstheSET UP OFFSET soft key
2. Pressthe CANCEL OFFSET softkey. The positionoffsetvalueis set to zero.
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