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Google Earth

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I have gone on Google Earth and identified several spots that I wanted to navigate to. I plugged the GPS coordinates from Google Earth in to my Garman. When I was on the water and attempted to navigate to those coordinates using the Garman, I was nowhere close. What am I doing wrong? An example is that I marked the opening for the Southeastern Louisiana Canal in to Barataria Bay. Google Earth has it at 29.1556.31 N and 90.0620.30 W. That is what I put in to my Garman. When I attempted to navigate to those coordiantes on the water, I was way off by more than a mile. Can you help me out?
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your Plots
I could not attach a photo to this posting but look for another posting to you.

That post, has the photo of my plotting of y our position.

I have plotted the position as Degees, Minutes, seconds and hundredths of seconds. DDD,MM,SS.ss
using WGS 84 Datum.
As you can see it is at the mouth of the canal.

Try checking what DATUM is being used by the Google maps you used.

Some points about the errors:
Many aerial photo maps are NOT ORTHO corrected. The map that I used is an ortho corrected one.
I cant say if the Google maps are corrected, I suspect that they area not corrected maps.

Check the DATUM that you were using as compared to the DATUM used by Google. Different datum settings could amount for the distances you describe.

Check the position format that you are using. Trying to enter a different format than the unit was set up to use will cause the inaccuracies. you describe.

Check if the iPhone has access to the WAAS differential system. If it does not and your GPS unit does have it, your unit will be much more accurate, usually within 3 meters. Without the WAAS feature the accuracy will be 60+ meters.

Note the included photo of my plot.

Captain Paul
wrong format
u may have it in the wrong format of coordinates. I use homeport software to enter coordiates before loading it into my garmin gps and there are a couple of ways to report the same coordinates.
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GPS
Easier to upload them from computer. Need mapsource and a program to convert the files. You can download the file conversion program free on internet i forget what its called but its very easy once you get it. Also we download entire routes pre drawn on google earth onto the gps not just waypoints.
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Capt. Paul
Had the same problem sometime back. Search for the words 'map datum' under Capt. Paul's section on here. You will find everything you need to convert. Good luck.
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Google Maps
I second what Capt, Paul is saying. I believe that it is that Google Earth does not properly correct their maps. I have been tagging fish lately for the WLF tagging program. I notice that when I enter the tag coord. from my GPS, those coord. show up as a different location in the marsh on the tagging website and that site is using Google maps to display where the fish were caught and/or recaptured.

I have no doubt that I am entering the coordinates correctly on the web site.
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Online Conversion Tool
Check it out.
http://www.thejump.net/sunset/waypoint.htm
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GPS program file conversion
GpsBabel is the file conversion program. It's free on Internet to download. It will covert your google earth files ( .kml) to map source files (.mps).
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