NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: UNK
Date: 2015 Feb 2, 07:52 -0000
Dave,
Your plywood sextant looks great.
Anyone interested in building authentic looking antique nav instruments such as astrolabe, backstaff, octant, nocturnal etc , I recommend 2 good books.
1) Latitude Hooks and Azimuth Rings by Dennis Fisher
2) The Low-Tech Navigator by Tony Crawley.
Both give detailed instructions and you can cheat on the scales and Vernias, just copy those provided and print on photo paper.
Using scrap off cuts, cost virtually nothing to make. The 18th century style octant looks great and probably accurate to 2’ arc.
Best wishes
Francis
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of David Pike
Sent: 01 February 2015 21:12
To: francisupchurch@gmail.com
Subject: [NavList] Re: Most commonly used/preferred sextant among NavList members
You can always make your own. Around 1982, I had to make something as my final testpiece for my Post Graduate Certificate in Education as a tyro Craft, Design, and Technology teacher. I'd always regretted allowing my mother to give my father's marine sextant away, and even the plastic ones seemed very expensive, so I decided to make my own out of plywood. The trick is to make it big, as people like Tycho Brahe found. Then cutting the scale is easy. I seem to remember the technician in the workshop showing me how to use a dividing engine as a lathe attachement, but I'd never be able to remember how to use it now. I recall shooting stars on a bowl of water on a still night and being surprised to find the Hs was double what I'd expected. Taking instant values compared to always using an averager were also a pleasant surprise. I've got the shots I took somewhere around. As I recall it was accurate to 2 or3nm. My problem is no natural horizon. As soon as I get my new artificial horizon working, I'll have to start playing with the plywood again. Dave
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