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    Re: GPS out by miles
    From: Tom Sult
    Date: 2016 Nov 01, 20:16 -0500
    By far the most likely truth is... he is wrong. Significant chart error in N. Cal?  Not likely. GPS signal error... not likely. RAIM geometry out of optimal... maaaaybeee but not likely to give 5 miles. 

    I can tell you I have, on many occasions, felt my compass, GPS or Sextant was wrong. Turns out I was wrong.  Sometimes a discovery that can take hours or days of travel to figure out. 

    Given that on a small boat in big seas 5 miles might be a good sight... if a sight can be had.. GPS is still my primary by miles. Let's not go back to the bad old days. 

    Tom Sult, MD
    Author: JUST BE WELL

    On Nov 1, 2016, at 14:03, Frank Reed <NoReply_FrankReed@fer3.com> wrote:

    I recently heard a story about GPS fallibility. A sailor related his enthusiasm for celestial navigation. He said that he didn't trust GPS because "sometimes it's wrong by miles". He described sailing off the coast of North Carolina and he knew where he was, but the GPS placed him five miles from that location. I think there's a lesson here... What might that be? Of course without interrogating him in detail, which would have been rude, we can't really be sure what was happening here. What are some of the possibilities??

    Frank Reed

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