GPS location indicator errors

[Zeker]

I have an older GPS, a Garmin GPSMAP 162, that I mounted on the dash in my 16' open bow Bayliner. I replaced the speedometer with this GPS and currently use it for trolling speeds. In order to avoid possible electrical interference I wired it directly to the battery. The arrow indicating the boat's position on the GPS map is out of position; anywhere from 100-300 feet. I have moved the unit from the mount on the dash thinking that the window frame might interfere but it makes no difference. I called Garmin and they couldn't help. Any ideas?

 

[Pez Vela]

Re: GPS location indicator errors

The indicated lat/lon position of your boat is probably correct within normal GPS parameters. The 100-300 feet error you see is likely attributable to the imprecision of the chart (map) that Garmin has built-in to the unit (with respect to your particular boating location). You probably need a more accurate chart for your area. I'd ask around to see what other people are using on your waterway.

 

[dingbat]

Re: GPS location indicator errors

Check to make sure your datum reference is correct. It defaults out to WGS 84. Need to compare that to your map set. The setting in the "units" tab.

Make sure you have "Mapsource" turned on.

 

[Zeker]

Re: GPS location indicator errors

Check to make sure your datum reference is correct. It defaults out to WGS 84. Need to compare that to your map set. The setting in the "units" tab.

Make sure you have "Mapsource" turned on.

Thank you. The map datum is listed as WGS 84 and the Mapsource is on. I will next look into the accuracy of the built-in chart.

 

[dingbat]

Re: GPS location indicator errors

Thank you. The map datum is listed as WGS 84 and the Mapsource is on. I will next look into the accuracy of the built-in chart.

There are some known software problems with a couple of the mapsource chart sets. What charts are you using?

 

[Zeker]

Re: GPS location indicator errors

The map on the GPS was factory. I am trying to upgrade that map with MapSource BlueChart Americas version 4.01. Before I can do this I need to get my computer to recognize the GPS as a separate drive. I am using a serial port to USB adapter and but don't know if it is working. Any ideas on checking the adapter?

The USB connnector on the adapter cable had recessed pins. After getting the GPS on line I again called Garmin who helped me re-install the original map. I hope this is the fix I need. I will start a new thread next week if it doesn't. Thanks for your help.