NavList:

Paul,

You're welcome! I could have added that the various metal sextants also differ in radius and bulk, but I don't believe this has any practical impact on accuracy or precision. Going off the Internet, it appears that the Frieberger standard sextants have the largest radius at 175 mm, followed by Cassens & Plath at 163 mm, then Tamaya at 162 mm, Astra at 153 mm, and finally the Freiberger "yacht" at 142 mm. By comparison, the Davis plastic sextants have the largest radius of currently available new sextants at 180 mm. Again, though, I don't beleive this has any impact on practical accuracy as far as the metal sextants are concerned.

For example, my primary sextant these days is a Frieiberger "yacht" (which I chose because it's easy to stow on a small boat), and I've used it for lunars with absolutely excellent results. The avalability of "bells and whistles," rather than practical precision and accuracy, seems to be the main difference between the principal metal sextants. One small weakness that I've found in the Freiberger "yacht," for example, is that it has three index shades instead of four. In 99% of cases, that's not an issue, but I occasionally find myself wishing for an intermediate shade when there's a light cloud cover that makes the darkest shade impractical but the other shade combinations a bit too bright. For me, however, the convenience of the smaller size and light weight more than make up for that minimal drawback. But others' priorities may differ!

Best,

Denis