NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brian Walton
Date: 2026 Mar 25, 03:58 -0700
Steve,
The Saxa tube with log cot scale, slides inside the Pringles tube (with metal base still attached) with log cos scale stuck on. The cursor tube, with red pointers, formed from another Saxa tube, widened, goes over the 2 other tubes.
The dimensions of the cursor viewing port are not critical; you are just using the arrows to line up 2 points on the main scales. The original Bygrave was like this.
This Bygrave fits inside a whisky bottle container, together with a box sextant, and any amount of work sheets and other stuff.
I suggest you make a rough initial slide rule, and plav with it. Concentrate on just one scenario, eg mid-morning sun shot, North West sector, before firming up.
My interest was in finding out how to precalculate a sight, whilst hand flying an open biplane.
