As the World Turns

We received a couple of letters this month from people who had trouble setting the tide functions on their Casio SPF-40 watches. One reader, who lives on Long Island Sound about 30 miles to the west of us, was incensed-said the tide function didn’t work, and wondered if we’d actually tested the thing. I wrote back to say yes, we did, but that even the engineers at Casio couldn’t account for local variation in restricted bodies of water. I suggested that he just go down to the water and fine-tune the watch for high tide when it was high tide, which is what we did. It took a couple of tries, using the bracketing technique favored by photographers and artillerymen, but it was accurate. He wrote back, even more incensed, saying he’d been in touch with Casio, and that we were shoddy, dangerous journalists for not discussing in detail the lunitidal settings on the SPF-40 that would allow the user to zero in on local variations. Again I wrote back to say that whether you call them “fine-tuning” or “lunital,” when it comes to local tidal variation, they work best if you can take an actual look at the actual water, or at least consult the local tide tables. As I gnawed on our epistolary exchange, I thought about how willing and even anxious we’ve become to substitute electronic data for observation. In this case, we want a $150 Casio to behave like a good-sized computer running a dedicated tide-prediction program (a gnarly FORTRAN program, in NOAA’s case)-a system that can still be baffled in real life by any number of local influences, as any oceanographer would be quick to point out.The tides, given to us by a continuous rolling squeeze of the moon, and in many instances the sun, have always been fascinating to scientists and coastal sailors. Where I live, we have semi-diurnal tides, spaced about 6 hours and 12 minutes apart. Simple. But it’s also Long Island Sound, where water rushes in and out at the two ends-Hell Gate to the west and Plum Gut and The Race to the east-in ways that create big local variations all up and down the Sound. Add river mouths, depth variations, persistent winds, and it gets more interesting. Depending on your location on the planet, there are also diurnal moon tides-meaning one high and one low per day, and mixed tides of alternating diurnal and semi-diurnal-and even, apparently, strictly solar tides, as in Tahiti. I’d be glad to go and check that out if there’s interest. As I write this, it’s near the winter solstice. A few minutes ago there was a dark-red, striated smear looming below the ridge to our east. The smear turned crimson, then pink. The sun appeared briefly, an intense yellowish-rose, then disappeared completely as the day began, and will stay, in the classic, bone-chilling shade of gray that seems to be the work suit of southern New England in December. Tonight we’ll have some freezing rain.I wish I’d rousted out my daughter for that pre-dawn view. “Look at that-here comes our star,” I would have said. “It won’t get very high in the sky today-it’ll just go over that way, through the trees in a thumbnail arc, and settle this afternoon behind the woodpile. It won’t warm us up much, because our end of the world is tilted away from it. But in a few days, our path around that star will start bringing our end toward it again, and we’ll be getting warmer. Hey, guess who’s having summer now at the other end of the world? That’s roight, mite, eya frinds Dean Undah!”We’re privileged, in sailing, to have working relationships with the earth, moon, and sun (and, for some celestial navigators, with the planets and other stars). The ancient astronomers, Galileo, Newton, and those who built on what they learned-have helped entwine us, whether we sail Optimists or Volvo 60s, with some pretty titanic forces. You don’t get those relationships in many other pursuits.-Doug Logan