I can never seem to find my tide book when I need it. It makes a difference, because if the tide is more than halfway up I can take a shortcut. Less than half tide and I have to stay in the channel. Yes, I know “there’s an app for that,” but I like to leave my cellphone home when I go sailing.
Actually, I can make a good rough guess by the angle of the gangway, and by looking at the dryness or dampness of the rocks I can usually tell if the tide is going up or down. But it’s a crude estimate — I’ve considered making marks on the dock, so the position of the bottom of the gangway would show the tide height. Although, after I worked out the geometry, I concluded that a simple arrow on a vertical pole attached to the floating dock, pointing to a ruler nailed to a fixed piling, would be easier to build and much more precise.
The first task was to decide which piling to use. That was easy: the one near my boat that I walk past every time I go sailing. The second task was to figure out how to attach the post to the dock. The marina staff frowns on berthers drilling holes in their docks, but I found a naturally occurring hole in a steel plate that was part of a piling ring. It was just the right size for a half-inch by six-inch bolt. With a little duct tape, the five-foot-long aluminum tube was a snug press fit around the hex nuts.
Then I needed an arrow. That was also easy: a triangle cut from the bright-red plastic lid of an old office storage bin. And for the tape measure, after some digging, I unearthed an “engineer’s” tape marked in feet and tenths, not feet and inches. Just like the numbers in the tide book.
Then it was time to calibrate. I know that highs and lows occur at different times at different points in the Bay. I would apply the time and height corrections from the tide book, compare my gauge with the tide book prediction, and set my arrow to match. The only annoying part was having to explain to every sailor who happened to walk by why I was putting an arrow on a stick pointing to a piling.
Keep reading at Latitude38.com to learn if Max Ebb’s plan worked as hoped.