Teaching sun, stars and sextant in the age of GPS


To the editor: A little more than a century ago, Joseph Conrad sat for his mate and master’s tickets in the British merchant service.

The deep-water sailor and future novelist of the sea was examined in the core-curriculum of the mariner’s trade: winds and currents, lights and signals, seamanship and cargo handling, charter parties and bills of lading.

But he also had to demonstrate competence in that singular discipline — celestial navigation — without which the bulk of his nautical training and experience would have counted for nothing. In other words, he had to be able to find his way across the oceans of the world.

Not much has fundamentally changed in the 130 years since Conrad passed for master. Even in the age of GPS, the navigator’s basic tools remain the same: sextant, timepiece, nautical almanac.

But where Conrad sweated with through a thicket of trigonometric functions to determine his ship’s position, the modern practitioner has access to simplified sight reduction tables like HO 249 and hand-held calculators that solve what in effect are problems in practical astronomy. Relying on a built-in almanac, these remarkable devices work almost instantaneous sight reductions of sun, moon, stars and planets. They provide a resulting digital display of geographic fixes as well as rhumb-line and great-circle sailings.

Capt. Shashi N. Kumar, academic dean at the U.S. Merchant Marine Academy, Kings Point, N.Y., is quick to acknowledge the wealth of guidance-system technologies available today. Still, he said, “I cannot imagine calling myself a mariner if I am completely ignorant about celestial navigation.”

To earn deck licenses as third mate, students at the academy must pass a U.S. Coast Guard exam that places heavy emphasis on celestial. The course of study is intensive: five hours a week in classroom and laboratory. The syllabus includes the definition and uses of time, the locations and apparent motions of celestial bodies relative to an observer on Earth, sight reductions of sextant observations, and plotting lines of position.

The teaching load at Kings Point is fairly typical of instruction at similar institutions nationwide. At the Maine Maritime Academy, for example, in the lovely little harbor town of Castine, celestial is also a major requirement for students pursuing a Coast Guard unlimited third-mate’s license or an ocean endorsement to a limited-tonnage license.

For aspiring deck officers at Maine Maritime, subject matter, as at Kings Point, ranges broadly across the theory and underlying principles of deep-sea navigation. Catalogue listings highlight the essentials of nautical astronomy as well as sight reductions, noon sights, azimuths, and amplitudes of the sun.

Hands-on instruction is not neglected. On summer training cruises aboard the 500-foot training ship, State of Maine (Capt. Leslie B. Eadie III), and the 92-year-old auxiliary schooner Bowdoin (Capt. Eric Jergenson), sextant practice, sight reductions and working positional fixes are as much a part of the day’s routine as are seamanship and safety drills.

Yet despite the Maine academy’s requirement for celestial proficiency, its role in navigation has been diminished, according to Capt. Peg Brandon, associate professor of marine transportation.

 “There has been a revolution in navigation technology since World War II,” she said. “Radar, loran, satellite navigation…and now the integration of GPS and various sensors…into the electronic bridge of today and tomorrow makes our maritime work safer, faster and more efficient.”

Nevertheless, Brandon asserts, “celestial navigation continues to have a role in the mariner’s ‘tool bag.’” She points to offshore compass checks as an example of what she calls the discipline’s value. Detecting and correcting magnetic and gyro errors, she said, “is still conveniently done via celestial amplitude or azimuth.”

Echoing Brandon’s words, the Massachusetts Maritime Academy, Buzzards Bay, cites in campus literature “the ability to use celestial navigation in time of need” as a key objective of its robust course offerings in the field. And it defines that need specifically “as a second check [on electronics] and as a backup navigational system.”

Capt. John Carlisle, adjunct instructor in navigation at Mass. Maritime, expands on the school’s official policy by suggesting that “celestial navigation ties a mariner to the natural world in which he lives.” Carlisle notes that the subject touches on mathematics and earth sciences as well as on the mechanics of nautical astronomy. He said, “the link between nature and the theoretical knowledge that celestial navigation encompasses makes, in my opinion, for a sharper and, frankly, smarter mariner.”

Elsewhere, the two government military academies responsible for educating the next generation of fleet commanders disagree sharply over the worth and usefulness of celestial instruction. As befitting the federal agency that oversees the licensing of civilian mates and masters, one of the two, the Coast Guard, continues to teach celestial at its own officer-training institution, in New London, Conn.

Lectures at the U.S. Coast Guard Academy stress basic theory supplemented by practical exercises in a weekly lab setting. As at Kings Point, Castine and Buzzards Bay, the standard texts used by cadets are Bowditch’s The American Practical Navigator and Dutton’s Nautical Navigation. On summer cruises on board Eagle, the Coast Guard’s square-rigged, 295-foot school ship (Capt. Raymond W. Pulver), sextant work is pursued in small study groups or as part of navigational watch teams.

Lt. Daniel M. Wiltshire is course coordinator of the academy’s navigation program. He is also an unapologetic cheerleader for a branch of learning he has spent much of his professional career advancing and teaching. “Even in this high-tech age,” he said, “the practice of celestial navigation has enduring utility to Coast Guard officers.”

Wiltshire argues that the Coast Guard demands celestial competence in large part as a check on electronics. “For cutters operating in the open ocean,” he said, “celestial navigation remains an accepted means of verifying the accuracy of a GPS position, and may be the only means available.”

He went on to say that an added benefit of celestial instruction he’s found while teaching cadets “is that navigation becomes more ‘real’ when a fix is determined with a sextant rather than plotted via GPS coordinates.

“There is simply no substitute for a sextant in hand when it comes to creating that confidence-building ‘ah-ha’ moment when cadets realize they can accurately determine the ship’s position without electronic assistance.”

Not so at the U.S. Naval Academy, in Annapolis, Md., where epiphanies like this one are things of the past. With satellites capable of pinpointing a vessel’s position to within a few yards, conventional wisdom at Annapolis has consigned the sextant to a dust bin of maritime relics as quaint as the knotted log-line.

The academy’s posture is unequivocal. “The use of the sextant is no longer taught at the Naval Academy,” spokeswoman Colleen Roy said bluntly. And without the sextant, there can be no celestial navigation.

Roy would not directly address specific reasons for abandoning sextant instruction. But she did say that while Annapolis still gives officer candidates a theoretical overview of celestial, the Navy’s current standards of navigation “stipulate that encrypted GPS is the primary fix source in open ocean waters.”

She notes what she describes as the evolution in the teaching of navigation at the academy over the past 10 years, a shift that has come “in response to changes in Navy requirements.” And those requirements, she explains, now center on “practical instruction in the use of” electronic software programs.

That said, there was a time when navigators in sail and steam like Conrad recognized the true greatness of a traditional tool which, if practiced with skill, would bring them safely to port. The U.S. Naval Academy notwithstanding, at least for now that historic legacy remains intact.
But it is fraying at the edges.

Maine Maritime’s Capt. Brandon: “Going forward, celestial navigation will have less and less emphasis in our crowded maritime-academy curriculum.”

And she adds: “Until it disappears completely,” it stands as an important intellectual foundation “for students who, as tomorrow’s mariners, will be better prepared to tackle modern maritime challenges by critical thinking skills honed through the age-old art and science of celestial navigation.”

—Alan Littell, journalist, novelist and former merchant mariner, is a longtime contributor to Ocean Navigator. His novel of the sea, Courage, was published in 2008 by Thomas Dunne Books/St. Martin’s Press. He lives in Alfred, N.Y.

By Ocean Navigator