On Halloween night we had a good idea of exactly when we should be able to cross Mud Bay to return home after celebrating in town. Days before, I’d used tide plotting software to pinpoint our crossing times, based on the 13 foot tide mark, the highest water we can comfortably cross the creek in the bay in regular rubber boots. As the night unfolded, we realized we’d be finished early. We looked at the tide book, and saw that the difference between the nearest high tide and the next low would be 12 feet—perfect for calculating the tide in our heads, using “the rule of the twelfths.” We calculated that we could cross a half hour early, so when we finished trick-or-treating, we drove to the bay.
When we hiked down to the beach, we knew immediately that something was not right. We hit water way too soon. Soon, we waded to our knees in our hip boots, which meant that when we stepped down into the creek, we’d be up to our waists, or deeper.
Obviously, we’d misread the tide software, and had botched our mental tide calculations. Luckily, KHNS was broadcasting a highly entertaining dramatization of Washington Irving’s The Legend of Sleepy Hollow. It didn’t take much discussion to turn us back to the road, to sit and listen to the end of the show before trying to cross again.
As the hapless Ichabod Crane raced the Headless Horseman, we saw our neighbor pull up to the parking area in his car, get out, and head across the bay. We could follow his progress by the glow of his headlamp. It slowed, stopped at the creek, then winked out.
Our show finished, we again headed across the bay. We found our neighbor seated on a rock, contemplating the too-high water of the creek. I made an attempt to cross, but had to turn back. A few minutes later I tried again, crossing the creek successfully, literally an inch from the top of my hip boots. This was about 10 minutes before we should have been able to cross the creek in regular boots. At most, the creek level should have been just below knee high.
Our neighbor, who has lived here several years longer than we have, had miscalculated as well. That seemed odd.
The next day, we compared notes with other neighbors. Some reported finding the creek too high on the rising tide as well. No one seems to know why this might be.
Tide plotting software and the rule of twelfths are models, of course. The actual height of the tide in a given place at a specific time depends on many factors—the set of the current and wind, the amount of rainfall, the topography of the area, and more. But, these indicators, plus a modicum of local knowledge has served, in the past, to allow us to predict the movement of the tides with a reasonable amount of accuracy.
Until now. Something seems to have changed on Mud Bay, and we’re at a loss to say what.
This situation will bear watching. A lot of people depend on reliable tide prediction. We’ll be vitally interested in seeing if the apparent change will become the new norm or not. It’s a mystery.