Three Ways to Capsize a Boat - Chris Stewart [33]
Mike, John, and Patrick were making use of the trip to brush up on their navigation techniques, taking advantage of Tom’s considerable skill. This was long before the days of GPS, and an ability to use the sextant was essential for ocean navigation, quite apart from the fact that mastery of this traditional instrument was an art in itself. Navigators have relied upon this beautiful device of gleaming brass for hundreds of years, and just to slip one out of its case and hold it to your eye casts you into the unbroken spell of time that links you to Columbus, Magellan, or Henry the Navigator.
The ideal time to take a sun sight on a sextant is at noon, although of course this is not always possible, as the sun is not necessarily shining at noon, especially in the dismal latitudes toward which we were heading. In theory, though, you can take a sight at other times of the day as long as the sun is visible above the horizon and you have an accurate watch. But if it isn’t noon, it complicates the calculations no end.
On our boat, if the sun were visible just before noon, the navigators would gather on deck and prepare their instruments. Then, as the moment of the zenith approached, they would adjust the ingenious little smoked mirrors to catch the exact moment the sun ceased its climb and started to drop. That was exact celestial noon, and the figures so accurately etched into the brass arms and arcs of the sextant could now be read off and entered into the calculations. This was also an opportunity to check the accuracy of the chronometers, that is, our watches.
Next everyone would tumble down the ladder to the chart table, where there would be a frenzy of calculations and poring over navigation tables. Then there would be such sucking of pencils, and muttering and leafing through pages gray with tan and cosine and sine, and date coefficients and declination and other unfathomable logarithms, until the final calculation was made and an estimate of our position arrived at.
Although I dearly wanted to be involved, there were only three sextants onboard and it became obvious that if I were to muscle in on the master classes, it would all become a bit of a scrum. For the first couple of days, I graciously bowed out. But on the third day the desire to navigate got too much for me; I cracked, and, seizing a moment in the afternoon when everyone else had returned to their bunks or allotted tasks, I crept up on deck with Tom’s sextant and took my own sight. It wasn’t a particularly opportune moment to take a reading, but it would have to do. Unhurriedly and with all the figures at my disposal, I busied myself down at the chart table all on my own with the complex calculations.
My deliberations moved inexorably toward their conclusion, until at last, panting mentally from the excess of mathematical gymnastics, I had the numbers. Excitedly, I drew in my lines across the chart, trying vainly to ignore the little copses of half-rubbed-out pencil marks that indicated everybody else’s approximation of our whereabouts. These were quite closely grouped.
However, as my pencil slid along the ruler toward the spot where it would intersect with my first plotted line, the truth began to dawn on me that things were not as they seemed. I removed the ruler and stared, brow furrowed, at the crossed pencil lines. Either everybody else was wildly out—which seemed to me the more likely option—or else I myself had slipped up badly. For my estimate of our position, far from being about fifty nautical miles southwest of the northern tip of Denmark, as the other navigators tended to agree, had us high and dry on the top of a prominent hill just to the south of Scunthorpe.
Hurriedly I rubbed out the lines. It seemed best to keep this disappointing discovery to myself. In fact, I resolved to