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Old 07-29-2002
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Tania Aebi is on a distinguished road
Praising the Sextant


Achieving competency with celestial navigation always brings its own rewards, not the least of them the ability to pinpoint where your vessel is
One of my proudest accomplishments was when I learned celestial navigation. It happened at a time when I could have been in college reading and writing about the classics. Instead, I was on the ocean, putting trigonometric celestial triangle theory to practice. Across three oceans and as many seas, every single day, I pulled out the sextant, my electronic watch calibrated to the universal time tick provided on the shortwave radio, the HO 249 tables, dividers, ruler, plotting sheets, and the Nautical Almanac. Along with the sun, moon, stars, and planets, these reference books and tools helped me to calculate and determine lines of position and pinpoint a spot on all that water. Each time the tiny cross was drawn and labeled on the space between landmasses on the chart, I felt the same exhilaration and satisfaction. Best of all, not only did the sextant enable me to locate my place on the planet, but I understood the principles behind the process, which reinforced a sense of connection between my boat and the universe.

Celestial navigation didnít come to me overnightóthe learning curve was steep and prolonged. When I was 17 years old, my father first introduced me to the sextant during an Atlantic crossing. I had already figured out simpler coastal navigation, and he could see I was ready to move on to the noon sight. He handed me a plastic Davis sextant and taught me how to aim it, locate the sun in the mirror, pull the orb down, and swing the sextant until the bottom edge of the sun barely grazed the horizon line. We would time each otherís readings, go down below, follow the formula and establish the noon sight, obtaining a pretty precise latitude and an approximate longitude. On that trip, this was as far as I got, and, really, the only accuracy one gets from a noon sight is with latitude; the more complicated method of acquiring longitude seemed too advanced for me at the time.

One year later, I was on my own boat, somewhere in between New York and Bermuda, totally lost. Before leaving New York, I took an evening course in celestial navigation. During the days I worked as a bicycle messenger and when class time rolled around, it was all I could do to keep my eyes open, much less concentrate on the theory and the vocabulary. I just didnít get it and I flunked. If the interest were just a hobby, failing the class wouldnít have mattered. But, my next step was a circumnavigation, with no help from satellites.


It's nice to know that some of the more highly touted race navigators customarily rely on the use of celestial. Here, renown West Coast sailor Mark Rudiger grabs a sight while racing across the Pacific.
My boat was too small and wet for the sensitive Sat Nav available at the time. Before leaving and still safe on shore, I over-confidently figured the same mail-order course my father had learned from would be sufficientóthat and a smug conviction that being out in the middle of the ocean would be the best motivation to learn. If my father and plenty of other people had mastered the art before, I could do it too, I kept telling myself. Besides, every book Iíve read on sailing, at one point or another, expounds on how easy celestial navigation really is, how it is just a matter of addition and subtraction, and applying these basic math skills to some tables and a formula.

In those first months at sea, I had no idea that one day I would be writing the same thing. Nothing had ever felt so complicated and uncooperative. Using my fatherís mail-order course, I tried to get the morning and afternoon sights, to do running fixes, but even the noon sight wasnít working anymore. I sailed to Bermuda, extrapolating figures from tables, adding and subtracting until I was dizzy, and never coming up with anything that resembled accuracy. I eventually got there by dead reckoning and heading southeast until getting within the range of an RDF station that emitted a signal in a 150-mile radius from the island.

I used the same approach until just before my next landfall in St. Thomas, when I radioed a ship for my position in time to alter course before hitting Puerto Rico. As for the Caribbean crossing to Panama, there is so much shipping heading in the Canalís direction, all I had to do was fall in line and follow them in. And, once again, on the way to the Galapagos, the comfort of a daily position eluded me. If it werenít for lucky timing with a sporadically functional RDF signal on San Cristobal Island, I would have missed the Galapagos entirely, and it would have been 3000 miles until reaching the next group of reef-encircled islands. That was about when I figured it was time to fix the problem.


You needn't own the best-made sextant to navigate accurately, but long-range voyagers know to have a back up one stowed away somewhere.

Ever since, I have chastised myself for not getting help sooner, for not doing something about it in Bermuda. The fear and malaise fed by the situation were totally unnecessary. But, now I see it was pride that got in my way. Here I was, ostensibly this single-handed circumnavigator, and nothing could get me to walk up to some impressed sailor on the dock and admit I was having navigation problems and needed guidance. I was determined to solve it on my own, and if worse turned to worst, I figured I could always hang a right and hit land somewhere along the North American coast. This approach, though, didnít work in the South Pacific, where huge reef systems and hundreds of islands lay between me and Australia, the next major land mass.

My life then depended on accurate positions and I had scared myself enough to do something about it. Fortunately, in the Galapagos, there was another boat with people who had become good enough friends that pride lost its steam. Once the truth was outed, we got busy. I dinghied over to their boat with my notebook full of sights and calculations, plotting sheets with LOPs, and the sextant. It didnít take long for the three of us to see that I was the only one who knew what I was doing, what with all the practice. They had been using a Sat Nav for so long that I found myself giving them a refresher course. Still, three brains are better than one for solving a perplexity, and, in the end, the problem turned out to be the sextant.

I had clung to the familiar, using the same plastic sextant on which I had practiced the noon sight with my father over a year before. For nearly 3,500 miles I lived with anxiety and worry stemming from the certainty that a mathematical handicap was preventing me from learning something that had allegedly been ďso easyĒ for others. Four months of one failed sight after another convinced me they were all liars. It never occurred to me that the instrument might have been at fault, that a well-used plastic sextant could have warped after having been left out in the sun one too many times.


The notion that just grizzled old navigators rely on the sextant is a folkloric misrepresentation of what actually happens aboard most serious cruising boats.

In the locker under my bunk, there lived an excellent aluminum Freiberger sextant I had been saving for who knows whatómaybe the day the plastic sextant fell overboard. It was a little more complicated to use, which was why I hadnít taken it out of its case, but ultimately much easier to adjust for errors. I had become so comfortable with the principles of the sextant that it only took a few minutes to get past the initial intimidation and, from that day on, my navigation was perfect. For the next two years, the days at sea were structured around the sights needed to acquire a position, and the result was the highpoint. I aimed that Freiberger at the sun, moon, planets and stars, extrapolated figures from all the tables, measured angles and azimuths, and always found myself. In the process, I became totally attuned to how the Earthís orbit correlates with what we see in the heavens, the progress of time, and my connection to both.

Nowadays, I still own two sextants, a different Freiberger and another plastic Davis, which, in the age of the GPS, has become something like owning two spinning wheels. Iím not a crusty old-timer; Iím not even middle-aged, yet, so this isnít coming from someone who also remembers walking to school uphill both ways with newspaper for shoes in the middle of winter. Only 15 years ago, when the GPS was still unavailable, the alternatives to the sextant were the Loran and Sat Nav systems, both of which were unreliable, and difficult to maintain, especially on small and leaky boats. For me, and most of the sailors I met who couldnít afford yet another repair of the broken Sat Nav or Loran, the sextant was the way to go.

Over many shipboard meals, instead of discussing how to set waypoints into a handheld computer, different makes of sextants, navigational tables, and methods were the topics. Instead of looking down at a digital readout, these sailors were watching the horizon and the heavens. Anecdotes were abundant. Everybody had a hint or trick for getting better lines of positions, or good times for taking sights, or shortcuts to shooting the stars and moon. Everybody also had a story about a time when their navigation was way off and how the problem got resolved. Of course, I had my own.

Above all, to a person, a lot more satisfaction has come from discussions about celestial navigation then than anything GPS-related can generate. I own and use a GPS now, but figuring out how to turn it on and get coordinates was no more challenging than finding a bathroom light switch in the dark. Certainly, the GPS has revolutionized navigation, as much as the invention of the chronometer once did, and itís a nice tool to have, but Iíd still hate to see the science of celestial navigation disappear like an obsolete language. No qualitative comparison can be made between a little plastic box full of terminals and chips, and the heft of a sextant. One provides a mere convenience, while the other a dialogue with history, tradition, and the universe. Plus, celestial navigation is a fun, enriching the experience of any voyage at sea.


Suggested Reading:

Basic Celestial Concepts by Jim Sexton

Working with the StarsóCelestial Navigation by Jim Sexton

Celestial Navigation by Dan Dickison


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