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The Eternal Optimist
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167 Posts
Discussion Starter #1
Following on from my posting re published lat/long on Volnay, it has been suggested to me that the discrepancey is due to use of differing GPS Datums i.e. not WGS84. Quite possible, but this set my mind thinking. Is a lat/long position not an absolute fixed thing, related to Greenwich Meridian and Equator? If I plot a position of a fixed feature on a paper chart I don't have to specify some arbitary datum that I measured from. So if a GPS is calibrated to refer to one datum and another GPS is calibrated to another datum, why don't they display the same lat/long if in the same position (within margin in error of GPS system).

Perhaps therefore all GPS positions given should include datum used as part of co-ordinate. I have only ever seen this on SeaSearch survey forms.
 

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The Eternal Optimist
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167 Posts
Discussion Starter #2
Please ignore this question!!! I have just looked the subject up on Wikipedia and it now makes sort of sense. The Earth is not flat - what a revelation. Still, my suggestion that one should specify the datum along with any lat/long is still valid.
 

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Please ignore this question!!! I have just looked the subject up on Wikipedia and it now makes sort of sense. The Earth is not flat - what a revelation. Still, my suggestion that one should specify the datum along with any lat/long is still valid.
I told you it could be complicated!
 
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