A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Joel Jacobs
Date: 2006 Jan 30, 22:42 +0000
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-------------- Original message from Frank Reed <FrankReedCT@AOL.COM>: --------------
> Joel Jacobs, you wrote:
> "There were limited quantities of Navy MK II sextants made with polarizing
> filters for use in WW II. Every once in a while one will surface."
> That's what got me wondering. I've been playing with one of those recently,
> and it seems like an effective design. Also, in the 1962 Bowditch, the first
> sextant pictured in article 1503 "Micrometer Drum Sextant" is a Navy Mk II
> with polarizing filters. The text in this edition reads "Older sextants have
> two sets of shade glasses, as shown in figure 1504. Many modern sextants are
> fitted with a single Polaroid filter of variable darkness in place of each set
> of shade glasses, as shown in figure 1503a." Of course, it's not really a
> "single" Polaroid. It's a pair mounted in a single unit --one with fixed
! > orientation and the other rotatable.
> And you wrote:
> " In general, they never really caught on in the navy or out."
> Any speculation on why not? They seem convenient to me. If I had my choice,
> I think I would prefer one standard shade of medium darkness and one
> polarizing unit for the greatest possible range of brightness reduction, in both
> locations where sets of shades are usually found on sextants.
MY PERSONAL OPINION IS THAT MANY EUROPEAN SEXTANTS USE DIFFERENT COLORED SHADE GLASSES WHICH OFFER MUCH GREATER DEFINITION AND DISTINCTION UNDER A WIDE VARIETY OF ATMOSPHERIC CONDITIONS. I DON'T THINK YOU CAN GET THAT WITH POLARIZING SHADES WHICH ARE ALL THE SAME COLOR VARYING ONLY INTENSITY. THAT DOESN'T ANSWER WHY TODAY MOST SHADES ARE NEAR ALL THE SAME GREY GREEN COLOR AND WHAT DIFFERS IS THE DEGREE OF FILTERING OR THE RANGE FROM LIGHT TO DARK WHICH IS SIMILAR TO MY CRITIC OF A POLARIZING SHADE.
MAYBE THE BIG BUGABOO IS THAT WHEN SUBJECTED TO SALT SPRAY THEY TENDED TO FREEZE AND ALSO FROZE IN FEARCELY COLD CONDITIONS.. AND INTRODUCED ABOVE AVERAGE SHADE ERROR OVERALL.
OTHER THEN THOSE, I HAVE NOTHING TO OFFER.
> And you wrote:
> "Capt. Sorreson of Coast and Simex fame was a proponent, and you see many of
> the Simex brand, a private label, with them."
> I think I have a cousin of a Simex sextant. It's marked "International
> Nautical", and it's a Tamaya-alike in appearance. It's not a Simex by another
> name, is it? Despite its rather "generic" branding, it has proven to be a
> remarkably accurate instrument by every test I've subjected it to. It has nice,
> large polarizing units instead of standard shades. The rotating parts were
> stuck ARE YOU USING THIS TO MEAN FROZEN AS I OPINED ABOVE?
SIMEX WAS AN ACRONYM FOR SORRESON AND SEXTANT. HIS WERE MADE FOR HIM BY SOMEONE OTHER THAN TAMAYA, MAYBE MAC WHICH WAS MEASURE ALL CO. TAMAYA MADE ALL OF NAUTECH'S PRIVATE LABEL SEXTANTS AND VISUALLY EVERYBODY'S LOOKED ALIKE.
> rock solid after years in the box (this instrument was apparently never
> used), and I half suspect that a previous owner or two did not realize that the
> shades were polarizers at all. There's a picture of one of these here:
> (mine was a lot cheaper
> Joel, you have apparently written on this topic before on the list. I've
> found replies to your messages on 'Tamaya and Simex' and all that in the list
> archives, but for some reason I can't find the original message(s). So I would
> appreciate hearing what you know about this.
I HAVE LOST ALL MY OLD EMAILS ON THIS COMPUTER DUE TO A CRASH AND MY DESKTOP HAS A DEAD MONITOR SO THE FILES THERE ARE INACCESSABLE. I HAVE A SECOND COMPUTER THAT I CAN CHECK. BUT RIGHT NOW I HAVEN'T TIME TO RECONSTRUCT WHAT I WROTE. I RECALL SOMEONE ON THIS LIST HAS AN INTEREST IN SIMEX SINCE HE OWNS ONE AND MAY HAVE SAVED WHATEVER I SENT OUT AND CAN ADD HIS OWN KNOWLEDGE ABOUT COAST NAVIGATION SCHOOL IN ITS EARLY YEARS.. IS IT MIKE BURKE?
> 42.0N 87.7W, or 41.4N 72.1W.