NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: GPS and Great Circle
From: Dave Weilacher
Date: 2002 Oct 8, 11:25 -0700
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 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 Myrvaagneswrote: > 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