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Monomoy Tidal Vectors


Adam Bolonsky

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In the course of researching a story I'm writing for On The Water about the crossing I made with Mark Stephens to Muskeget by way of Falmouth and the Vineyard a couple of years ago, I came across a pretty awe-inspiring flash movie that compresses 12 hours of tidal vectors into a nine seconds. The whiplike, elastic interconnectiveness of Nantucket Sound's tidal currents are amazing to watch, as are the spurts at Great Point, Wasque Point, through the Muskeget Channel and off the tip of South Monomoy.

Here's a crucial de-interlaced frame. If NSPN web hotshots can give me a hand, I can supply the entire set of swf files and maybe we can host the swf movie as a compressed planning resource (a Quicktime movie) here on the site?

The flash movie and related PostScript files are from Dr. Chen's lab at UmassDartmouth.

Here's Monomoy Island soon after flood tide starts at Pollock Rip (data and forms familiar to anyone who's looked at Eldrige.)

Note how flood at Pollock Rip gives you a counterclockwise free ride up along the western flats of the Monomoys, then back down along the eastern open side to the new land bridge (not shown on the image) at what once was the South Beach gap:

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In the course of researching a story I'm writing for On The Water about the crossing I made with Mark Stephens to Muskeget by way of Falmouth and the Vineyard a couple of years ago, I came across a pretty awe-inspiring flash movie that compresses 12 hours of tidal vectors into a nine seconds. The whiplike, elastic interconnectiveness of Nantucket Sound's tidal currents are amazing to watch, as are the spurts at Great Point, Wasque Point, through the Muskeget Channel and off the tip of South Monomoy.

Here's a crucial de-interlaced frame. If NSPN web hotshots can give me a hand, I can supply the entire set of swf files and maybe we can host the swf movie as a compressed planning resource (a Quicktime movie) here on the site?

The flash movie and related PostScript files are from Dr. Chen's lab at UmassDartmouth.

Here's Monomoy Island soon after flood tide starts at Pollock Rip (data and forms familiar to anyone who's looked at Eldrige.)

Note how flood at Pollock Rip gives you a counterclockwise free ride up along the western flats of the Monomoys, then back down along the eastern open side to the new land bridge (not shown on the image) at what once was the South Beach gap:

On The Water is a favorite Zine of mine, even though I'm not a power boater.

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Hey Adam - that was really, reall cool!

It is a little scary when you look at the vectors from the southwest side of the tip that direct you straight out as opposed to around in an outgoing tide.

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Hey Adam - that was really, reall cool!

It is a little scary when you look at the vectors from the southwest side of the tip that direct you straight out as opposed to around in an outgoing tide.

Yup. Key there, I've found over the years, is to hug the southernmost tip as close to the island as possible - there's an eddy. As long as there isn't dumping surf on the berm (it can be huge at the tip) you can paddle close enough to the island to spit on it. Meanwhile the eddy whips you around the corner.

But that vector you noted really is fierce. Mike Hirsch and I driftfished that rip in his zodiac last summer. The standing waves were so large and abrurpt I was fearful the whole time that I was going to get tossed out of the boat.

More eerie to me, though, is the velocity and mass of the current at the Muskeget Channel, off Wasque Point at the southeasternmost tip of the Vineyard.

Mark and I, as you probably remember when we planned the trip in Warehom, felt real trepidation about getting sucked into the rip there. (Or at least I did.) Apparently there's a 1/2 acre sand island off the channel, called Skiff, that appears in the area for an hour or so on either side of low tide, then disappears for good every once in a while every few years.

We timed the crossing from Cape Pogue to Muskeget so that we would avoid the power of Muskeget Channel. We did avoid it - but we ended up paying pay a very high price nonetheless several hours later, when we began to battle the rip a mile off Muskeget Island itself.

Holy moly, that final mile to the island took us well over an hour. The fast and swirling water was so turbid with suspended particles of sand that you would have thought we were paddling in a river of quicksand.

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