gps discrepancies

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sundancer9000

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the garmin 750 s on boat is not right. its lat and long position read out is different than the other gps a north star. On paper chart the northstar unit is correct. The difference is fr exampe 54.48 and 54.28 and 006.29 and 006.42 any ideas??????
Unusally both gps are exact for navigation use ,,,, confusion persists?
 
sundancer9000 said:
the garmin 750 s on boat is not right. its lat and long position read out is different than the other gps a north star. On paper chart the northstar unit is correct. The difference is fr exampe 54.48 and 54.28 and 006.29 and 006.42 any ideas??????
Unusally both gps are exact for navigation use ,,,, confusion persists?
Click to expand...

  1. Establish which one is correct and which is wrong
  2. Check the chart datum on the northstar is configured to WGS84?
  3. It's possible your paper charts are not WGS84, so the northstar may be configured to the paper charts datum, hence the difference as the Garmin will be set to WGS84 out of the box
  4. Both GPS's units should have their chart datum set to WGS84
  5. Check also the display setting for lat/long (ie dd mm sss or ddd mm.mmm, etc)
 
If it because of a different datum then the difference or offset should be fairly constant, because that is all the datum is.
 
sundancer9000 said:
the garmin 750 s on boat is not right. its lat and long position read out is different than the other gps a north star. On paper chart the northstar unit is correct. The difference is fr exampe 54.48 and 54.28 and 006.29 and 006.42 any ideas??????
Unusally both gps are exact for navigation use ,,,, confusion persists?
Click to expand...


The one reading 54.48 is set up to read minutes and decimal points and the one reading 54.28 is reading minutes and seconds....Both probably giving the same position?????

There will be setup choices for you to make both read the same.
 
sundancer9000 said:
the garmin 750 s on boat is not right. its lat and long position read out is different than the other gps a north star. On paper chart the northstar unit is correct. The difference is fr exampe 54.48 and 54.28 and 006.29 and 006.42 any ideas??????
Unusally both gps are exact for navigation use ,,,, confusion persists?
Click to expand...

That's a long way off, give Garmin a call.
 
sundancer9000 said:
the garmin has an internal antanae and the northstar has external
Click to expand...

That would be a very big boat !

Looking that 54.48 would give 54 deg 28.8 minutes (0.48 *60) this would indeed look like decimal degrees being displayed instead of minutes but it's not the same for the longitude (I cant see how 006.29 and 006.42 can be the same problem) therefore I'd be more inclined to look at the datums but in saying that after looking through a few converters from one format to another I can't clearly see where the problem is - are these two values that you are quoting correct?
 
I dunn0, but with my new Garmin, self propelled, and my rathion Big thingy. I can see my marina and berth. OK it might be 3 ft out. Dunnno if the berth is 3 ft out of position or the Garmin is out. It'smost likely they built oit in the wrong place.
 
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