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Wednesday 4 August 2010

Rafting the Shubenacadie River Tidal Bore

Bay of Fundy, Nova Scotia

Tidal bores occur in areas of the world where tides are unusually large and are funneled down into a narrow bay or river. For example, the Qiantang River, which flows into the East China Sea, produces the bore shown below on the Vernal and Autumnal equinox. It can produce a huge wave front from the ocean which flows upriver at an average speed of 40 kilometers per hour and with crests reaching up to nine meters at its banks,


Cook.s Inlet in Alaska also produces impressive tidal bores. Here's a picture of one from Turnagain, about halfway up the long inlet.


The height of the tidal bore depends on the height of the tide, which depends on the phase of the moon. We draw a very unimpressive tide, but we take what we can get.


We approach the Zodiac down a long, very slippery mud bank. My dive booties are not ideal for traversing slippery mud. I end up on my butt twice, covered with mud. Take the boots they offer if you try this yourself.



Jeff drives us to a sandbar. The river is flowing out strongly at 4:10 PM. Suddenly, a small wave front approaches the sandbar and within a minute the bar disappears as the river rises.



The incoming tide creates standing waves about five feet high and five feet apart on sandbars. Jeff drives the Zodiac though the waves. The Zodiac swamps and fills with water repeatedly. Everyone is drenched by the waves breaking over the bow. We have a "man" overboard. We stop and pull her out. When the tides are really strong the standing waves reach a height of 15 feet.



Eventually, we return to base to get more gas. I store my camera to keep it dry. We go mud sliding for awhile down a slippery mud bank and then hit more big standing waves. It begins to rain. I'm impressed with the ability of the Zodiac to fill completely with water and accelerate and drain itself.


We return eventually for hamburgers, hot dogs and hot chocolate provided by the tour operator. It was a good time.

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