gillean said:
The other sextants, which were kept in the chart table for general use by watch keepers, were a lower class. It seems to me that they were all British manufacture but by various manufacturers and with some minor differences in design and function. They all looked to date back to at least WW II and perhaps earlier.
That accords with my memory. They were typically good quality Hughes & Son (aka 'Husun') sextants, but elderly - not necessarily a bad thing - and 'well-used' (more of an issue). In other words, the navigational equivalent of the old Browning pistols.
Pieman said:
What seems to be the most dominant sextant today came from a Japanese company, called the Tamaya sextant with various versions in WWII era. It became popular and became known as the 'merchants' sextant since it was used on cargo ships. Over the years the company switched names/owners, and the modern version of the 'merchant sextant' is the Astra IIIB.
Not quite.
Tamaya sextants are still made (in Japan), and both their standard "Jupiter" and premium "Spica" models have good reputations for fit and finish, including the optics. They are not cheap: expect to pay ~US$2,000 for a new one. Many are still found on merchant ships, but due to cost factors they have been largely superseded by the Freiberger trommelsextant, made in Germany.
The Astra IIIB is made in China by the Changzhou Celestaire Instrument Co.: which has no affiliation with Tamaya, and indeed is one of its competitors. The Astra is a favourite of yachtsmen and backyard celnav enthusiasts because it is of reasonable quality and relatively inexpensive (~US700). Although not a top-grade instrument, it is widely available, perfectly useable and very good value. The same comments apply to Russian SNO-T / CHO-T sextants.
Pieman said:
There are some fancy ones out there costing $3k and up. Costly optics and glow in the dark readings for siting faint stars.
The sextant manufacturer generally - although not invariably - acknowledged as the best currently available is Cassens & Plath, of Germany. They don't cost >$3,000 though: their top-of-the-line model, the Horizon Ultra with polarized shades (see
http://www.wired.com/gadgets/gadgetreviews/magazine/15-07/st_tool), costs no more than US$2,000.
Of interest, the Royal Navy now issues Cassens & Plath sextants, identical to its "Professional" model with two exceptions: (i) they fitted with Chinese-made Luger MD 6x30 lightweight monoculars rather than C&P's standard Japanese-made 6x30 prismatic monocular - a questionable choice, in my opinion; and (ii) although made in Germany by C&P, they are rebranded on the arc as being made by the British distributor Lilley and Gillie.