Tuesday, September 29, 2015

Super Moon, Super Tides

 I hope you all got to see the lunar eclipse yesterday. I thought it was quite fantastic. I finally had a reason to learn about using my camera in "manual" mode. I like the pictures, so I take the liberty to post them, even though they have nothing to do with windsurfing.

Well, almost nothing. We do have a nice little storm coming through in a few days. The National Weather Service predicts gusts up to 35 knots. Fun! Might be a good time to wear a helmet with a visor, though - there will also be some rain.

 The wind will be out of the north and northeast, so the places to sail will be on the Cape Cod Bay site. Normally, we have about a 10 foot (3 meter) tide difference there; you have to watch tide levels before going out on many spots, or you may have a long walk back.
But the moon being very close to Earth right now, and it is still almost full. So the tides the next few days will be exceptionally high (and low). For Duxbury Bay and Barnstable Harbor, the predicted low tide levels are - 2 feet, and high tides exceed 12 feet several times - that's a 14 foot (4 m 20) tide!
If the wind indeed blows hard out of the northeast for a couple of days, it will push a lot of water into the bays, and the actual tide levels may be even higher. A couple of extra feet at some of the more exposed beaches would be no surprise. That could create a few problems.
 If you are planning to go windsurfing near Cape Cod the next few days, make sure to check the tide tables, and use caution. I am listing a few things that come to my mind for my favorite N-NE launches below.
 Duxbury Bay will probably be mostly unsailable near low tide. Last Monday, we sailed there at a +1.6 foot low tide, and had about 4 feet of water under our boards at many spots. With a -2 foot tide, there'll be less than 1 foot of water at many spots. Unless the wind pushes a lot of water into the bay, most of the north side will be dry, and a lot of the south side will be too shallow near low tide.
 Fortunately, low tide is early in the morning and again after dark. But at and after high tide, there may be a lot of reeds on the water, which can stop you dead. It's still early in the fall, so the problem may not be really bad, but bring your weed fin! Assuming, of course, the Duxbury Harbor Master does not close the bay because of a storm warning.
 Chapin should be sailable for much of the day, but keep in mind that there will be a lot of water flowing in the outgoing tide. The currents near the Barnstable Harbor entrance will be significantly stronger than during a normal tide. The rip currents may also be quite strong. So exercise caution if you go! And post some pictures :-)

Pleasant Bay may be a great spot once the wind turns NNE-NE. No worries about rip currents or harbor masters! But keep in mind that the Jackknife Cove can flood at high tide. The tide is delayed by about 2 1/2 hours relative to outside beaches - it will close to 5 pm for Thursday.
 The predicted high tide level for Pleasant Bay of 4.0 feet is 0.4 feet higher than last Saturday, when a small part of the road near the lot entrance got wet. I sailed there only the second time last Saturday, so I don't know how much the wind pushes the water into the cove, but I'd definitely watch the water levels closely in the afternoon!
This could be a reason to explore the other nearby landings, for example the one at the end of Strong Island Road. But there are shallow areas near Strong Island which might be too shallow to sail near low tide.
Back to the moon: the pictures on the left span quite a variety of exposure times, from 1/250 at ISO 100 to 2 seconds at ISO 800 (all at f/5.7). That's a difference of 2000-fold! Quite amazing how the eye adapts to such differences.

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