At Large
Tide-rode
By Doug Cabral - October 18, 2007
Had the moon been full instead of waxing crescent, and had you been overlooking Great Harbor at one o'clock that morning, your attention would certainly have been drawn to the stocky, nearly naked sailor draped around the bowsprit of the yacht, trying desperately not to flop overboard as he threaded another thick rope through the shackle above the mooring buoy.
As the screeching westerly blew up his shorts and carried away his curses, he wondered why his stern and the stern of his boat were pointed into the piping wind. It should have been the other way round, especially with the wind blowing a small gale as it was. The wind ought to have been smacking him in the face.
Of course, the yacht was tide-rode, and the question he was really asking himself was how strong the wind would have to be to take command of the situation. Neither the wind nor the current - the yacht, fairly deep draft, was under the influence of the current created by the ebbing tide - swept the boat onto the nearby rocks that night, though either one would have done so heedlessly. But as it happened, the current had its way with the yacht for about six hours and twenty minutes, then changed directions aligning itself with the wind, and peace returned to the moored yacht.
In the vicinity of Woods Hole, the other home port for so many of us, tidal currents rule, but as often as we navigate its shoals and ledges, we rarely notice. Most of the time, we're on the cell, fast asleep, deep in a book, or chatting over a beer. We don't know or care which way Nantucket Sound, Vineyard Sound, and Buzzards Bay are running.
Back for a moment to the sailor, dangling from his bowsprit. On another occasion, that same sailor was traveling east from Buzzards Bay, with the flood current running hard in the hole. The sails were set, but in the hole the wind failed completely, so the yacht was under power. The east-going current in Woods Hole actually sweeps right to left from Middle Ledge across Red Ledge - that's where you see the harbor seals sun bathing in the winter - toward Juniper Point - that's where the Airplane House is. So as the yacht drifted east, with no wind to direct her and without power because her fuel had been exhausted, dire consequences loomed. The current set her toward the rocky shallows below the Airplane House - which was not designed by Frank Lloyd Wright, no matter what you've heard. But, just as the skipper expected to feel the first thump as the yacht stumbled into rocks, the easterly current bounced off the land in front of the yacht and pushed her to the west, beyond the buoy that marks the end of Juniper Point and into a wind ruffle that set the sails to drawing, propelling the yacht out of danger and on her way to West Chop.
There is always more to the behavior of tidal currents than meets the eye, and nowhere is this more damnably so than in Woods Hole. Happily, Woods Hole is well supplied with indices to tell the story of the changing currents. As Edmund W. Jupp explains in Water Watching (Intellect Books, 2002), "The direction of the tidal stream in the vicinity of a buoy is often obvious from the appearance of the water surface round the buoy. There is a tendency for the water to pile up on the upstream side, and to form eddies downstream, just as though the buoy were being driven through stationary water.
"At the top of the tide or at low water the buoy is steady and the water lies round it at rest. When you see a buoy sitting quietly then, in tidal water, you know that the tide is on the turn, and ready to start a run for about half a dozen hours. As the tidal current starts, it will at first flow smoothly and quietly past the buoy, and the shoreline. The surface is glassy, in the absence of wind, and the water moves like treacle. Not till the speed reaches a certain value does the surface tend to break up. Ripples and eddies appear, and the features of fast flow are seen."
Or not seen by most of us, for whom Woods Hole is where we get on or get off.
