NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2026 Oct 26, 12:36 -0700
Chris Maness you wrote: “I just purchased a Link A-12 bubble sextant. Seems to be in really nice shape. It came with paperwork indicating that it had been serviced and sold by Celestare in 2007. That is really a fast drying rate. I am wondering if some seals or gaskets need to be replaced as well or is it normal for these to go bone dry in 19 years. That seems a short amount of time, but I have no reference.”
Chris
My first piece of advice is try nothing until you found out a lot more about the A12.
2. Try and find a manual. There is an excellent one available on eBay for £10.80GBP https://www.ebay.co.uk/itm/157987758476?_skw=A12+sextant+manual&itmmeta=01M5WSDX89PXCMD4KG4K8P68VZ&hash=item24c8cde18c:g:iDYAAOSwdnZaTRg9&itmprp=enc%3AAQALAAAA0CHNgUiiE%2FjQhlDTaMiAde%2FPcwPq7V79RXCiMzuXunM10KPpuLTf9OBYuDqvjwBncvYE9R1MiJtQvwyxALM0vn0h%2B%2BccKRJ%2B%2F8Ztbg1ykL4jVCyM8WjFLqZCZhYRKbDWrtXClKMaIflh1AnAkSV51qUFdk65mEGGq%2FPP3DNBZfyDPVfq%2BRm7ehMlOwYB08MVTt3b6q1A60%2FWZnO2clU9kqFcn%2BeEwFMwuhqzoMmnAUpxO%2FSNVvGPwXH6PfKAoxtbHZtRcHCd%2FLW2i5hvnceiE3g%3D%7Ctkp%3ABk9SR8DUt5mvaA by ‘mark-ix-sextant’ who was formerly 'tick-tock' something? He’s a good bloke (living in Wing, Rutland if you can find it on the map) and he really has taken these things to bits. He’s done a couple of MkIXs for me and also checked all my sextants for radioactive luminous paint. Only the A7 failed.
3. Did your A12 come with a spare bubble chamber? That’s what the big hole in the box is to hold. I tried to buy just the spare from Celestaire to make my box look complete, but I didn’t get a reply.
4. Did your A12 come with a tiny Bristol spline key for the bubble chamber and a slightly fatter one for the horizon mirror? Search carefully inside the box. They might be hiding under the felt lining?
5. Are you sure your bubble chamber is dried up. It might be so full there’s no bubble. This happens all the time with the Hughes MkIX. It’s less likely with the non-adjustable USA bubble chambers.
6. Be prepared to accept quite a large fixed instrument error, which is easily coped with rather than trying to adjust the index mirror with the fatter Bristol key. You’ll probably make it worse.
7. If you decide to take out the bubble chamber, pull back the battery holder with the black plastic end first, or you’ll smash the lighting bulb.
8. If you decide you must remove the grub screw from the bubble chamber, do it over a tray. Otherwise, if the screw falls off the end of the Bristol key, you’ll never find it again.
