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A relic’s lasting impact on ocean voyaging

I recently caught myself swinging the cat-o’-nine-tails. Hard and fast I brought it down on my own back — virtually, of course — punishing myself for doing stuff that was fun when I should have applied myself to serious matters, such as weeding the yard or contributing to the bottom line. The culprit was David Barrie’s new book Sextant, which is subtitled A Young Man’s Daring Sea Voyage and the Men Who Mapped the World’s Oceans (HarperCollins).

Winslow Homer's 1886 oil painting Eight Bells depicts two sailors using sextants, the modern navigation instrument of the day.

Oh brother, what was I doing? Reading about an instrument that I’ve never used, never understood and that technological advances exiled to history’s scrap heap, where it joined the typewriter, the slide rule, the VCR and the eight-track tape.

Skip it, my alter ego whispered. Let it go. It’s OK. You missed that boat. True, but I simply couldn’t put this tome down.

At first it felt a bit like a reunion of the spirits of the grand voyagers most of us have read about: Anson, Bligh, Bougainville, Cook, FitzRoy, Flinders, Shackleton, Slocum, Vancouver. But this rather Anglocentric collection of characters appears in a fresh light because Barrie looks at each of them through the prism of their navigational challenges as they roamed the oceans to fill in the white spots on the atlas.

Exploration was the X Games of the day, with a possibility of survival. Bad luck, bad weather, bad ships, bad manners, bad charts and sometimes bad judgment conspired to kill scores of sailors and legendary commanders, such as James Cook, who was slain by hostile natives in Hawaii in 1779, and the French explorer Jean-François de Galaup, comte de Lapérouse, who came to grief with his ships and more than 200 men in 1788 in the South Pacific. And returning safely did not guarantee fame and prosperity, if the travails of George Vancouver are any indication.

Barrie, an Oxford-educated, retired British diplomat and experienced bluewater sailor, deserves recognition for including the explorers’ personal stories and anecdotes from logs and journals, letters and notes detailing the fears, the loneliness and the depression some of them suffered, to say nothing of physical hardships. “Those voyagers in the late 18th or early 19th century either never made it home or died soon afterward,” the author says. “I suspect the rigors of these journeys and the extraordinary strains the men were put under took their toll.”

Author David Barrie

Especially tragic was the story of Matthew Flinders, who charted the coasts of Australia, where he also survived a nasty shipwreck. Later, he called at Isle de France (now Mauritius), incognizant of the fact that England had gone to war with France. Flinders was arrested and held captive there for years by a surly French general, causing him heartbreak and depression. “Perhaps the most moving moment during my research was holding the letters to his beloved wife in my hands,” Barrie recalls.

Not just a gadget

The sextant was predicated on the work of brilliant scientists such as Sir Isaac Newton and was a great improvement from the astrolabe and the reflecting quadrant. It led to the accurate determination of geographical longitude — at the time the holy grail of navigation — and the production of much more accurate charts. Two methods were developed nearly simultaneously, one using an accurate clock or chronometer and the other relying on observations of the moon. Both needed the sextant.

Unlocking the riddle of longitude was not just a scientific feat; it was of utmost political importance to the sea powers that were busy building empires, which required proficient navigation for the discovery, colonization and exploitation of new lands. The Spaniards were first to offer cash rewards for a solution, but it fell to the British to move matters along more swiftly.

The Longitude Act of 1714 put up the princely sum of 20,000 pounds (nearly equal to a lottery jackpot today) as a “due and sufficient encouragement to any such person or persons as shall discover a proper method of finding the said longitude.” Of course, with so much at stake, rivalry, jealousy and intrigue followed, none greater than the spat between John Harrison, the inventor of the chronometer, and Nevil Maskelyne, Astronomer Royal and influential member of the Longitude Board, who favored the astronomical method for shipboard timekeeping. And with good reason: From the 1770s until the 1840s, lunar observations were the only way of rating a chronometer’s accuracy.

“A wonderful invention though it was, the chronometer has received more credit than the astronomical methods of celestial navigation,” Barrie says. “I think that Tobias Mayer and Maskelyne and all those wonderful astronomers and mathematicians deserve much more credit than they are given.”

Using the celestial clock

The lunar method uses a sextant to measure the angular distance of the moon from another celestial body, which changes rapidly and predictably, thus serving as a “celestial clock,” as Barrie calls it. Developed at roughly the same time as the first chronometers, lunars were the only independent way of determining Greenwich time far out to sea, a laborious process that was gradually shortened and improved but always depended on the accuracy of observation and the information in the nautical almanacs.

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Until accurate time signals could be transmitted around the world via telegraph, which started to happen in the mid-19th century, navigators needed lunars to keep track of the rates of their chronometers. Interestingly, Joshua Slocum, who set out for his solo circumnavigation in 1895, also used lunars for his longitude calculations because he was too cheap to buy a good timepiece. “I threw up my sextant for sights,” Slocum wrote. “I found from the result of three observations, after long wrestling with lunar tables, that her longitude by observation agreed within five miles of that by dead reckoning.”

Another American in Barrie’s account is Capt. Thomas Sumner, who in 1837 approached the coast of Wales from the Atlantic but without the benefit of a recent accurate fix. He took a single timed sun sight and an estimated latitude to work out his longitude, which was an educated guess. Two more calculations using assumed latitudes 10 minutes apart farther north produced three points in a straight line, a line of position.

The Sumner Line, as it was called, was an important discovery that was initially considered helpful when approaching land without knowing the exact latitude. But the French later generalized this method to obtain a position line anywhere, anytime. “And if you have two position lines, you have yourself a fix,” Barrie says. ”And that’s the technique we all learned.”

The idea for the book, he says, had been with him for quite some time, dating from a scene in the film Mutiny on the Bounty where Fletcher Christian (played by Marlon Brando) dives into the cabin of the burning ship, trying in vain to save the sextant. But Barrie also delved into the memories of his own Atlantic crossing in 1973 when he was a lad of 19, sailing on a small wooden yacht from Halifax, Nova Scotia, to the U.K. under the command and tutelage of his friend and mentor Colin McMullen, who taught him the finer points of celestial navigation during that trip.

A few years later, Barrie tested the acquired skills as the co-owner of a Contessa 32 that he and a friend sailed from France to the Azores. “That was a very strange experience because I thought I learned all that stuff so thoroughly that I could not possibly have forgotten anything,” he says.

Without giving away too much, the devil in celestial navigation almost always lurks in the details and requires the practitioner to pay close attention.

Intuition and the art of seeing

But therein lies the caveat: If you don’t use it, you lose it. And today hardly anyone uses a sextant. Given that we only push buttons to find out where we are and where we need to go, we barely remember that the sextant once was a must-have instrument. Three hundred years ago it was a revelation to sailors who traveled far, even across oceans, without the means to exactly determine their position once land had dropped behind the horizon.

Long before that, Greeks, Phoenicians, Norse, Arabs and Polynesians traveled far without accurate charts, compass or sextant, relying on skills and the observation of clues from the environment. They’d probably laugh at the idea of outsourcing navigation to a government agency and morbidly staring at screens to learn what is patently obvious from looking around. These sailors were keen on sensual input and sailing by the seat of their pants. Or what’s in them: In We the Navigators: The Ancient Art of Landfinding in the Pacific, author David Lewis quotes one Capt. Ward, who wrote: “I’ve heard from several sources that the most sensitive balance was a man’s testicles, and that when at night or when the horizon was obscured, or inside the cabin, this was the method used to find the focus of the swells off an island.”

Citing a study of younger Inuit who have lost traditional navigation skills since the advent of GPS, Barrie encourages sailors to reclaim important turf. “I feel strongly that the increased dependence on satellite navigation has a detrimental effect on our ability to use our own senses,” he says. “On a more profound level, it’s affecting our relationship with the world around us, turning us into dummies who don’t use their eyes.”

I think I’d second that.

So what about my feelings of guilt and the urge for self-flagellation? Poof, gone. All that remained was the pleasure of an entertaining and educational read. Granted, I still don’t know the first thing about sight reduction tables or how to shoot a meridian altitude, but I gained a fresh perspective on something we take for granted today. And I hope Barrie won’t stop here. I think I’d like to see a prequel, an investigation of ancient navigation techniques that details what kind of cojones such techniques would require.

Dieter Loibner is sailing editor for Soundings.

August 2014 issue