A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Bob Goethe
Date: 2015 Mar 25, 15:45 -0700
A Davis Mark III is not a bad sextant. People have navigated across oceans with it...and I personally have gotten accuracy with mine comparable to what I get with a $2,000 Tamaya sextant. The Mark III has only one moving part, and it is not inclined to wear out. The biggest differences are that the Tamaya is much easier to read and much more fun to use. I try not to ask myself if that ease of use and fun was worth the additional $1,950.
Ironically, the Davis Mark 15 and Davis Mark 25, which are more expensive than the Mark III, are *less* likely to be accurate due to trying to replicate the gear mechanism of a metal sextant. Given that plastic wears rapidly compared to brass or even aluminum, the accuracy of these more-expensive Davis sextants is not as good as for the Mark III.
Alas, brass sextants never wear out, and aluminum sextants virtually never wear out...so the idea of picking up a used one for cheap is largely a vain hope. Most sextants built post-WWI appear to have appreciated in value, and sextants built pre-WWI can still be pretty pricey.
I took a chance once on an inexpensive metal sextant from eBay, and got something cut out of a piece of sheet metal with a jig saw, with numbers on the arc engraved by hand using some sort of vibrating tool. I was getting it for looks rather than utility, but it didn't even LOOK good. I recycled it.
Now, if accurate celestial sights are less your concern than LOOKING right in a piece of artwork, then (if you are willing to accept a plastic instrument to use in your work) a Davis Mark 15 could be perfect for you. It is about the least expensive purchase you could make of something that looks, from a distance at least, like a professional grade sextant.