The next ice cream social at the Chappy Community Center is on Wednesday, August 12 from 3 to 4 p.m. The new Chappy Ferry owner/operator, Brian Scall, plans to be there for a listening opportunity to have a conversation about the ferry with folks that lasts longer than 60 seconds.
If you follow the Edgartown tides closely you will notice occasionally something funny about the times of high tide. Let’s just look at one high tide as an example: the afternoon high tide on Wednesday, August 5. The prediction according to NOAA is wonky compared to the previous Tuesday afternoon tide and the following Thursday afternoon tide. Tuesday is at 4:54 p.m., Wednesday is at 3:30 p.m., Thursday is at 6:36 p.m. How can that be? How can the Wednesday high tide be earlier than the Tuesday high tide?
I have observed the Edgartown tides closely for half a century and intimately for the past two decades. The high tide is always later the next day. Usually by about 50 minutes. The tide predictions are based on the lunar cycle. As the moon revolves around the Earth it dependably passes overhead about 50 minutes later than the day before.
The Wednesday afternoon Edgartown time of high tide is an error in the NOAA tide predictions. In an effort to be polite, I call it an anomaly. None of our neighboring harbors have a mistake similar to it on that day. I figure that there is a glitch in the computer program that predicts the tides for Edgartown. My reason for caring is because the time of high tide can be important at the Chappy Ferry. Some big trucks can only board the ferry at high tide. If they show up at the wrong time, their wait in line is wasted time. Fortunately, the anomalies all predict the high tide to be earlier than the actual high tide. So we tell them to wait a couple of hours for the water level to come up. Still, it’s wasted time on their part.
About 15 years ago, the publishers of a graphic tide table, called Tidelog, agreed to publish an annual tide book specifically for the Chappy Ferry. The water level throughout the day is shown as a wave rising and falling according to the times of high and low tide. The graphic aspect makes it easy for truckers to determine when the tide will not only be at high, but also high enough. The height of the water levels vary with the phase of the moon. The graphic aspect is essential when addressing a language barrier. Every language the we encounter at the ferry uses the same clock numbering format.
When a huge box truck from New Jersey, with a Spanish speaking crew showed up at dead low tide, I showed them the Tidelog. I pointed to the spot where the tide wave bottomed out and shook my head to indicate no. Then I pointed to the spot where the tide wave crests and nodded yes. The clock times are printed right at those spots. After a few seconds with a quizzical frown on his face, the truck driver smiled and gave me a thumbs up. I returned the gesture and they came back right at high tide.
Each year, I peruse the new edition of the Tidelog, identify the anomalies, which are easy to spot with the graphics, determine mathematically what the correct times of tide should be and redraw the tide wave with a red pen. Some years there are only a dozen anomaIy days, other years thirty. I do this for each of the 50 to 75 booklets that the ferry purchases each year. Even though it’s a nuisance, the value of the clear graphics is worth the trouble.
The low tides, so far, have been consistently correct, which is all that you would care about to decide when to go clamming. If your sailboat has a deep keel and you have run it hard aground, you might have to be patient longer than NOAA has promised. Just be aware that if the time of high tide shown in your on-line tide table is earlier than the day before, it’s a mistake in the predictions.
This article appears in August 7, 2026.