Re: [Paddlewise] How a Kayak Turns

From: Dave Kruger <kdruger_at_pacifier.com>
Date: Mon, 22 Jan 2007 14:03:17 -0800
Bob Myers wrote:
> On 1/22/07, Dave Kruger wrote:

>> Aren't the water particles moving _up_ on the _face_ of the wave and down
>> on the backside?  If they were moving down on the face of the wave,
>> wouldn't the water level on the face be falling instead of rising?

> No...  circular pattern, not just up and down.  At the top of the
> wave, they move faster than the wave, forwards, and then down the
> face.  Think about what happens when a wave breaks!  The top of the
> wave is going too fast and can't complete the circle.

Bob, I think Craig's reference was to the _face_ of the wave, not the 
breaking crest, which does indeed topple after the broken crest moves ahead 
of the rest of the wave.

In swell, sure, circular motion, shifting to elliptical as the wave reaches 
shallower water.  But the issue is whether there is an upward component or 
a downward component on the face of the wave.  Don't have my Waves and 
Beaches at hand, but ...

Check out this animation and you'll see that the water motion on the face 
of the wave is _upward_ and rearward just as the trough passes, shifting to 
_upward_ and forward as the crest approaches; it runs too fast to see -- 
you'll have to stop it in mid-stroke:  http://tinyurl.com/5vawv

-- 
Dave Kruger
Astoria, OR
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Received on Mon Jan 22 2007 - 14:04:03 PST

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