NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2025 Jul 20, 11:22 -0700
Jan Eckert:
A couple of weeks ago you asked about Davis metal sextants (no, I don't think those exist), and you mentioned a Davis plastic sextant priced at over $1000. That seller is, let's say, "optimistic". You can find any Davis plastic sextant in very good used condition for less than $115 and usually less than $90. The simple Mk 3 sextants often sell for $30-$50. The very common and popular Mk 15 sextants sell for about $90. And tha Mk 25 sextants usually are priced a bit higher (I don't recommend the Mk 25 over the Mk 15, but some people do like them better).
There's another Davis sextant model that's less common and dates back to the 1960s apparently. It's the Mark 12. It has a vernier scale, no micrometer --see the photo below. These usually sell (used, good condition on ebay) for prices close to the Mk 15, but sellers can be talked down. Here's a comparison of the Mk 12 and the Mk 15. I find that they both yield sights with an error (in the 1 standard deviation sense) of abour 2 minutes of arc. The Mk 12 is a nice analog for historical vernier "octants" which were made of wood (hardwood... often ebony) instead of plastic.
Frank Reed
