NavList:

Thank you, Greg, for your advice. How would you rate the Freiberger 4x40? What about the higher-power scopes (C&P 6x30, Tamaya and Astra/Celestaire 7x35, Freiberger 8x30)?

Also, would you suggest to switch to a full-horizon mirror (from the half-horizon of my Davis), or just to keep the option open? I have attributed any frustrations I've had with the Davis more to the size of its mirrors and the limitations of its scope. But I might be wrong, as I have never used a full-horizon mirror. I'm asking because there seems to be a good supply of decent-looking used Freibergers here, but most of these come with half-horizon mirrors (though a full-horizon could be retrofitted, for a cost).

It sounds like a stiff arm or micrometer need not necessarily doom a sextant and that a DIY cleaning/re-lubricating could at least be attempted.

- Interesting take on bubble horizons, I hadn't seriously considered them for now, but out of interest: what makers/models would one look for? Are these of any use at sea, or more suited to aircraft and terra firma?

Thanks again!

Martin