NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brian Walton
Date: 2015 Jul 6, 05:14 -0700
Hello,
I was surprised to read that David Burch of Starpath has had no feedback concerning his "Nx" reduction method and tables.
In the 1980s, before Internet, GPS and mobiles, I was lucky enough to deliver some yachts from Europe to the Caribbean, and some new B 737s from Seattle to London. In Seattle, I found, bought and memorised David Burch's book and emergency card. I found the card too stiff, and, when cut and paste meant just that, made one up on paper covered with plastic.
An image of my version is attached. It has been and goes everywhere with me, and normally lives inside my - wait for it- Bygrave tubular slide rule, which lies on my - wait for it - d'Ocagne diagram, on my boat. You can see that I had figured out how to expand the Nx table.
So David Burch's work has been has been recognised over here ! Incidentally, the d'Ocagne diagram solves the azimuth calculation, as well as reducing Hs or Long by Chrono without multiplication, but not as accurately as the Bygrave, or the Nx table. Or the hav Doniol Hs...
Brian Walton
