A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Joel Jacobs
Date: 2009 Jan 06, 17:47 +0000
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-------------- Original message from "Trevor J. Kenchington" <Gadus@istar.ca>: --------------
Thank you, Joel. That was helpful.
> In the archives, there should be the history of much of what has
> been discussed lately on this site about sextants. On the earlier
> NAVLIST, I recall detailed threads that covered these subjects in
> detail. Those discussions covered:
> the founder of Coast Navigation, Captain Simonsen, and the Simex
> The problems with small scale (7/8) sextants, ie the law of similitude
> when the micrometer drum was invented and by whom
> when the endless tangent screw was introduced
> Private label sextants such as NAUTECH, SIMEX and MAC
> and so on and so forth.
> Perhaps some one can dig out those old threads.
Unfortunately, the Yahoo archiving system doesn't seem to be working
well. Searching on "Simonsen", "Simex" or even "micrometer" doesn't
bring up any messages save those posted in the last few days. I tried
searching for messages that I had posted and it would not admit to
any before June 2008, whereas I have been contributing occasionally
to this list for a number of years.
The NavList archives do have far more information (and more than
Google found for me when I tried a general search, rather than a
search of those archives). But I still don't have answers to my
A quick look at the archived messages produces firm statements both
that Simex sextants were made by Tamaya and that they were not. Those
who posted on the old Navigation-L were closer to unanimity that your
Nautech instruments were all made by Tamaya and that the MAC ones
were not -- even though they look identical in every detail save the
brand name. Current auction prices for used sextants are
significantly higher for an old Tamaya than for a Simex or MAC of the
same vintage. I'm still trying to figure out if there is actually any
difference in the instruments themselves (beyond the obvious options,
such as a choice of telescopes).
> A couple of comments off the top of my head. The Tamaya MS 1, MS 2,
> MS 3, were the Tamaya model designations which were the same as the
> catalog numbers, 635, 636, 637 so that the same sextant had two
> designators. The differences between the models were NO lighting w
> 7 x 35 scope, lighting w 7 x 35 scope, lighting w 7 x 50 scope.
In that case, Tamaya are doing what the auto industry does: They are
re-using old model designators for new models. At least, their
Japanese web site uses MS-1L, MS-2L and MS-3L for what seems to be
the same sextant that sells as the 733 Spica in North America.
> The MS series was a top of the line sextant using the same frame,
> as the 733 which succeeded it. The difference was that the mirror
> sizes were smaller. For example, the horizon. mirror was 50mm vs
> 54mm in the Spica which replaced it. It has a round handle which
> carried two "C" type batteries compared to the two "AA" in the 733.
> There was a version of the MS 2 that did not have batteries which
> was designated a 635 and one that was fitted with a bigger scope
> that was the 637. Basically, they were all the same and so close in
> appearance that they could be confused with a MS 733 Spica.
That explains the 635, 636 and 637 but not the 633, which shows up
regularly on e-bay. The 633 had/has a noticeably different frame from
the 733, with the MAC and Simex Mariner resembling the 633.