Difference between GPS and repeater(s)

[JeremyF]

Any idea why a repeater should show a consistant 3 degree difference to the Bearing to Waypoint on the GPS. I thought it might be converting True to Mag, but it seems not, as Ive checked the NMEA data header input on the repeater, and its True.

The GPS is Garmin 128 and the repeater is a Navman 3100

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[tome]

Almost certainly because you have the Garmin set up on Magnetic bearings and the repeater on True. Both bearings are transmitted by the Garmin 128 as part of the NMEA messages.

Go back and check the Garmin settings

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[JeremyF]

I think you are right, Tome. On rereading the manual the GPS default dispay is Mag.

Given the GPS is at the chart table, and the repeater is up near the compass, wouldnt it more sense to reverse this and have True by the chart, and Mag at the helm?

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[tome]

Jeremy

This is how I have it set up, although the Garmin is on deck and the repeater below so I use the Garmin default Magnetic. My repeater is an ICS Navtex unit which displays all GPS, compass, depth/speed, wind etc and also logs it all at 15 min intervals - an awesome piece of kit which is also a dual frequency Navtex receiver.

Regards
Tom

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[toad]

Intresting,I have a Navman plotter and a Raymarine repeater,the time on the repeater is allways 30mins out.On talking to Raymarine they said that Navmans NMEA is not quite the same as theirs.I can adjust it in 1 hour increments but not 30 mins.Maybe Garmin is the same as Raymarine

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