Sextant

Sextant: A Young Man's Daring Sea Voyage and the Men Who Mapped the World's Oceans

David Barrie (2014, William Morrow)

In 1973, David Barrie sailed from Maine to England aboard the thirty-five foot sloop Saecwen (Anglo-Saxon for 'sea queen'.) Along the way, Barrie, then nineteen, learned celestial navigation from the ship's owner, Colin McMullen, a retired Royal Navy captain. Today's satellite-aided navigation was a decade and more in the future, so, for three and a half weeks, the sun, moon, and stars were the only way they had of knowing where they were. 

 

The story of the crossing is full of small adventures, like trying not to get hit by larger vessels, and surfing before gale-force winds that threw up awe-inspiring waves. Excerpts from Barrie's journal also recall the small annoyances of life at sea: the tight quarters; the lack of exercise, fresh food, and sleep; and, sometimes, the boredom. Yet no two days were exactly alike: "People sometimes complain of the monotony of the sea, but it is, with the sky, the most changeful of all natural spectacles. Its surface, brushed by the wind, whether gently or with violence, presents patterns of of infinite variety, and its color too undergoes astonishing transformations, depending on factors like the time of day, the depth of water, and the weather."

The voyage of the Saecwen is the framework for a longer, larger story, of how heroic mariners of the eighteenth and nineteenth centuries explored and mapped the Pacific Ocean. Captain Cook and Captain Bligh are familiar enough names, but to read about what they actually did, and lived through, is thrilling. Barrie also piques our interest in Louis-Antoine de Bougainville, who sailed around the world by way of the Falklands and Tahiti; George Vancouver, who mapped the northern Pacific areas that bear his name; Robert FitzRoy, who, in addition to captaining Charles Darwin's voyages on the Beagle, developed the use of the barometer as a weather prediction device; and many others.

The tools and methods these men used were being developed at the same time. The sextant reached its modern form in 1731, and a timepiece useable at sea was tested in the 1760s. In the North Atlantic, Barrie learns to fix the Saecwen's latitude by measuring how high the sun is at noon; if he also knows that it's half past two at Greenwich at that moment, he can establish her longitude as well. The first-generation chronometers were not reliable enough on their own to assist in mapping the Pacific – some mariners traveled with a dozen or more. Sextant readings of the angle between the moon and the sun or certain fixed stars (once predictive tables had been developed and published) also helped explorers fix crucial longitude readings for the islands of the Pacific.

Facility with the sextant has begun to decline in the age of the satellite; American naval officers don't learn celestial navigation unless they are specialists. Of course, electronic systems run the risk of all sorts of failures, from jamming equipment to sunspots, so it is probably a bad idea to be exclusively dependent on GPS. More than that, there's the grandeur of the thing: "When I recall learning how to handle a sextant all those years ago, I see myself, a transient speck of life, fixing my position on the surface of our small planet by taking the measure of vast, unimaginably distant suns whose lives are measured in billions of years. The chastening contrast between their calm majesty and my fretful pettiness was overwhelming."

Email publication, September 1 2015