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Subject: Re: GPS and Great Circle
From: David Weilacher (daveweilacher@XXX.XXX)
Date: Tue Oct 08 2002 - 14:25:57 EDT
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
reduction.
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
you.
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 <rodneym@XXX.XXX>
wrote:
> 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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