A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Michael Bradley
Date: 2018 Apr 8, 02:18 -0700
I would go for the second hand C&P, for three reasons.
1.Aluminium sextants suffer dreadfully if the the paint coating is comprimised - they quickly corrode and be come non-refurbishable.
2.The Cassens and Plath has a polariser horizon shade which vastly improves the image in conditions of glare reflected off the sea. The use of shades to get a 'quiet' image improves the accuracy and repeatability of the sextant altitude in general.
3. I own a 4 year old second hand Cassens and Plath, a recent Astra, ( and an aluminium Freiberger Yacht Sextant ), and have done side by side comparison tests on them by observing and correcting index side error using a mid intensity star at night. The C&P optics are just better, the double star image is much the most useable. It's the mirrors I believe. ( The conditions of test included using the same telescope on the C&P and Astra to eliminate the telescope as a factor )