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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Michael Bradley
Date: 2025 Jan 4, 04:41 -0800
Franks's post mentioning telescope alignment has prompted this post about my CPlath serial number 25095, implying a 1945 build date. Conditions in Hamburg at that time were awful.
The micrometer drum has 1/2' markings. The horizon mirror is round.
The mirrors were tired. The original 'scope, x4 40mm, suffers from a poor quality objective lens, which I couldn't free so as to replace it. Also there was a considerable misalignment in the bracket/yoke setup somehow with respect to the horizon mirrors which are likewise 40mm diameter.
The case was a poor thing, in rotten gappy softwood and poor ply.
Inially a new float glass index mirror was made by a friendly local glazier. The split horizon mirror was refurbished by an optical shop.
By happenstance I came across a Kingston surveying sextant, mid 1970s vintage, and bought it cheaply for spares. That Kingston model was a bronze direct copy of the CPlath, with a very nice German x4 40mm 'scope which might replace the sad original CPlath, and a fancy hardwood ply fitted case. The newer 'scope fits the original yoke with a short section of 50mm ABS pipe to provide an interference fit sleeve. The 'scope misalignment was fixed by me drilling out one of the frame holes for the mounting bracket and turning the hole into an arc with a small round file, then replacing one fixed position original set screw with a nut, bolt, and washer sitting in an arc for alignment adjustment.
All my other sextants have gone to new homes, and the working CPlath is a cobbled together probably unsellable mash up, while being the sweetest instrument I've ever owned....
Michael Bradley
