NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Precomputing sextant observations at sea
From: Brad Morris
Date: 2014 Jan 30, 00:33 -0500
From: Brad Morris
Date: 2014 Jan 30, 00:33 -0500
Gary
It doesn't sound hokey to me at all. In your mind, you are flying with Chichester and the Bygrave is the artifact that brings it together.
I experience the same feeling holding (the same model as) Worsley's sextant and going through his equations on that amazing journey from Elephant Island.
Brad
On Jan 29, 2014 11:22 PM, "Gary LaPook" <garylapook@pacbell.net> wrote:
This is going to sound hokey. I read Chichester's book many years ago and that was where I first heard of the Bygrave slide rule, and everybody knows of my interest it now. I had felt a kinship to Chichester because I know what it is like to cross the ocean at ten thousand feet and 90 knots with only one propeller on the nose of my plane and a sextant in my hand. I was always impressed that he had managed to do this in an open cockpit biplane. In 2009 I was in England and had the chance to fly the same type of plane, a Gypsy Moth bi-plane, and I found out how difficult that type of plane is to keep under control so my admiration for Chichester went up a couple of notches. I had looked at Chichester's navigation before but I had never gone into the detail like I just did in response to Francis' question. Yesterday I used my Bygrave to repeat Chichester's computation and, there it was, the exact same values coming off my Bygrave that Chichester saw coming off of his Bygrave on April 1, 1931 in the middle of the Tasman Sea. It really struck me, I was looking at the same reading he was looking at. It was a thrill. I told you this would sound hokey.
gl
From: Francis Upchurch <francisupchurch---.com>
To: garylapook---.net
Sent: Wednesday, January 29, 2014 7:04 AM
Subject: [NavList] Re: Precomputing sextant observations at sea
Thanks Gary,
I knew you would get the answer! How stupid of me not to see that!( I would have missed the island and drowned!) Despite my interest in the Bygrave, I'de not thought of doing that. Just done it and got same result! Thanks!
I'm now excited about my planned trip using the simpified pre-computed LOP/ Hp graph method you have described.
I'll send draft plan later.
Many thanks again for all you help and a fascinating thread on this.
Francis
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