SEXTANT PROJECT - Part Two

In his excellent book, The Nautical Sextant, W.J. Morris describes in intricate detail how to refurbish an old sextant, such as my Simex. I’ve been following his procedure as closely as I’m able. The first phase is disassembly, which after a little more than a month I’ve gotten to the end of it. Morris describes altering and using thin blade screw drivers to take apart the various components while not buggering up the screw heads.

I (mostly) got everything disassembled. One trick he revealed is to be patient with penetrating oil to get into seized threads to loosen stuck screws. I had to let a couple of them sit for a week or so; but now everything is free that needs to come off.

I proceeded with corrosion and tarnish removal. So far I’ve gotten the big pieces fairly cleaned, more detailed work will have to happen on some specific areas: the track in the scale arc, the battery connections for the lamp, and some of the more fragile of the sunscreens.

The best overall method I’ve used so far was vinegar baths, a surprisingly good way to get years of corrosion off the brass and aluminum. Some places will need metal polish, which is where I am at the moment. My intention is not to bring the sextant back to some new-looking, flawless finish, but to get it instead into “working” order and corrosion free. It’ll still look like an old sextant with paint missing, etc. I don’t want a museum piece, just a useful instrument that looks like it belongs on a boat.

Since I’ve had long experience with telescopes I wasn’t hesitant to take apart the small galilean scope and get it back to working order. The vinegar baths took care of the external and internal brass parts and my secret lens cleaner formula has the lenses spotless and protected. The little scope is back together now (with a trace amount of Liberty clock oil to keep things free and moveable).
 

Galilean scope brass parts de-corroded.

Meanwhile the horizon mirror has been sent off for re-silvering, (I was lucky that the index mirror is still serviceable and nearly flawless.) which takes a while to complete. There’s only a few places in the world now that know how to re-silver sextant mirrors and they do them in batches when they have acquired a certain number of them. The really helpful guys I chose were Island Marine Instruments Co. in Everett, WA.

‘Tween now and Christmas I’m busy doing spot corrosion removal on the frame, adjusting the index arm and micrometer, and hunting down a new bulb for the little arc lamp.

It’s all going well, I think.

SEXTANT PROJECT - Part One

So my bucket list has "Become Proficient at Celestial Navigation" near the top of the list. I've always wanted to possess and use a good sextant, and thus be able to navigate and find my spot on the planet without resorting to 'lectronic wizardry. (Instead, all that's required for non-'lectronic navigation are: Trigonometrics, Big Fat Charts and Tables, highly accurate wristwatches, hyper competence, and ... a sextant.) Come to find out, navigating is as complicated as most of us on the outside always suspected it was. 

First step, after acquiring a lotta how-to books, was to obtain a sextant; which is this fancy tool to measure sun, star and other 'celestial' movements. It's kind of a drafting compass on steriods.They are (still) damned expensive, despite the fact that almost everyone has switched to GPS units* and the aforementioned 'lectronic wizardry. Earlier this year I was able to acquire a pretty nice Davis Mark 15 sextant. Despite being made of plastic, it is a reliable tool to find all this complicated stuff out. I like it a bunch, and it has allowed me to make many of the newbie mistakes novices have to make in order to learn. I'm getting better at using it, learning a lot and am now able to find the location of my house about a third of the time.

Anyway, I still have this desire to own one of those high-dollar metal sextants that used to be the standard for practicing celestial navigation. You can practice 'lectronic navigation wizardry for about two-hundred bux or less. Metal sextants run anywhere from six hundred to more than a thousand bux; even used ones. I started looking on ebay and everywhere to find a deal, since on my limited income stream owning a metal sextant seemed beyond my reach. I eventually discovered this neglected, trashed-out and  corroded Simex sextant in serious need of restoration. Since as my friend Todd Settimo has noted, restoration/rescue is my "thing" I'm confident I can bring this sextant back. It was 80 bux delivered! Researching it I found that it was made by the Tamaya sextant folks for a celestial navigation teacher to sell to his students so that they would have a good, reliable professional sextant. It's not the highest level of sextant, but certainly right in the mid-range of better-than-good instruments. Right now this particular one of mine is a piece of crap with parts damaged and lots of corrosion. It came out of one of the vessels the ship-breakers in India take apart. Gawd knows what it has been through over the years since the 70's.

Luckily I know where to get replacement parts; and since I am the King of Restoration/Rescue I have confidence and no doubts that I can bring this old instrument back up to operational goodness. Yeah, yeah, there are gonna be an abundance of celestial navigation nerds warning me that a newbie shouldn't try to work on such a delicate/fragile instrument and that it's damn near impossible not to screw up some essential setting or accuracy calibration. Nah. Not to worry. With me, the restoration is in good hands, and - as a back-up -  I know a guy who can do the final inspections and set-ups.  For a little elbow grease, some bottles of chemicals and some good tools I'm sure I can get this sextant to live again, all within my budget.  I'll keep y'all in the loop as I work through the transformation. Meantime, my Davis Sextant and a good watch are reliably teaching me all the basics ....

*One trouble with GPS units: https://www.wired.com/story/spoof-jam-destroy-why-we-need-a-backup-for-gps/