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Using a Sextant for Navigation

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Going Back For Backup

Can you believe? A celestial voyage down memory lane!

Many years ago, during what often seems like another lifetime, it was my job as a U.S. Merchant Marine officer to shoot a couple sun sights a day with a sextant, weather permitting. The task was a pleasure, really. It called for a set of physical skills that a guy like me could first learn, then practice, and then finally master in an almost artsy, albeit seriously practical way.

What a kick I used to get out of the whole extravaganza. There’s nothing—absolutely nothing—quite like strolling out to the bridge wing with a stopwatch hanging around your neck (synchronized with a time tick from the single sideband radio), raising a properly set up sextant to one eye or the other, briefly manipulating the index arm and the micrometer drum to seemingly bring the sun down to the horizon you’re looking at through the telescope, and then, once the sight’s mechanics have been double- and triple-checked, popping the stem of the watch and carefully recording a bunch of figures in a little notebook. The sense of accomplishment’s plumb uplifting.

But what used to be even groovier still was the quiet but intense kind of excitement that typically followed the eventual plotting of an actual position on a chart via the calculation of a reasonable latitude and a longitude that was, let’s say, off by no more than five or six nautical miles, at least when compared to the flickering numbers on the trusty ol’ chart-table-mounted satnav, an ancient form of pre-GPS navigation device that only worked when you absolutely did not need it.

Astra IIIB sextant

Which brings me straight to at least one of the reasons I’ve decided to purchase one of the Astra IIIB sextants shown above (they sell for about $659 new from Celestaire [], although you can find one that’s considerably cheaper on eBay) and then use it to refresh my celestial-navigational skills. One way or another, I flat-out enjoy navigating with little more than a glorified protractor, my very own hands and eyes, a copy of Pub 249, and a mind that is most certainly old but probably just about as sharp as it ever was.

Of course, there’s one more reason I’ve decided to get back into celestial—backup! I’ve come to the conclusion over the years that, given the vagaries of life afloat, a little redundancy on the navigational front may be rather a good idea. Yeah sure, there’s no greater advocate than I when it comes to the glories of modern GPS technology and what it’s done for safety, positioning accuracy and timeliness, and convenience, both ashore and at sea. But then again, what about lightning strikes? Water damage? Momentary fades? And unexplained, downright shutdowns, particularly during long open-water passages?

I know. I know. Reclaiming a skill I more or less abandoned 30 years ago may take some effort. Just browsing briefly through the sextant-related products that are on the market these days has shown me I’ve forgotten a lot.

But I’m remembering a lot, too. And I’m apparently in good company as I set out upon this little adventure, at least according to “Smitty,” a fellow at the Big Apple’s New York Nautical ( shop at 158 Duane Street , who’s a legend of sorts among hardcore navigators, whether they be professional or amateur. “We’re still sellin’ lots of sextants,” he told me recently, “and it’s mostly young people who are buying them—guess they just wanna know how things work, wanna do things with their own two hands. Instead o’ just punchin’ buttons on a GPS.”

Young people, eh? Stay tuned for further developments. There’s nothin’ says an old dog can’t learn new tricks. Or relearn a trick he’s sorta forgot!