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    Re: GPS and Great Circle
    From: Dave Weilacher
    Date: 2002 Oct 8, 11:25 -0700

    I proved my Garmin 45XL GPS provided GC bearing by reducing a GC route from
    Florida to Bermuda using HO 229.  It's bearing agreed exactly with the sight
    If you don't know how to do this,  set up a waypoint on your GPS, then post
    your current lat/lon, the WP lat/lon and the bearing in true that it gives
    There are a whole lot of well qualified people on this list that would be
    pleased to check it for you. (I'm betting)
    On Tue, 8 Oct 2002 12:56:46 -0500 Rodney Myrvaagnes 
    > Joe,
    > That would depend on the firmware in your
    > particular GPS receiver. You
    > could determine the answer by asking it to
    > point to a series of
    > waypoints all at your current lattitude. If it
    > calculates great circle
    > the initial heading will be more toward the
    > nearer pole for the more
    > distant waypoints. If not, it will point true
    > east or west for all of
    > them.
    > On Tue, 8 Oct 2002 09:41:00 -0700, Joe Winlock
    > wrote:
    > >I am a lurker in this group and actually know
    > only a smidge celestial
    > >navigation. I hope my question is not out of
    > place here. I am curious
    > >whether my GPS follows the great circle route
    > or Mercator rumb line when
    > >plotting long distance courses?
    > >Thanks for patience with the dummy,
    > >Joe...
    > Rodney Myrvaagnes                        J36
    > Gjo/a
    > "If Brecht had directed 'Waiting for Godot,'
    > he would have hung a large sign at the back of
    > the stage reading 'He's not going to come, you
    > know. ' "   -- Terry Eagleton
    Dave Weilacher
    .US Coast Guard licensed captain
    .    #889968
    .ASA certified sailing and celestial
    .    navigation instructor #990800
    .IBM AS400 RPG contract programmer

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