Re: [Paddlewise] How a Kayak Turns (was: Mind Experiments ...)

On 1/22/07, Dave Kruger <kdruger_at_pacifier.com> 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?

Here is a quick quote from http://www.mos.org/oceans/motion/wind.html:

'As a wave arrives it lifts water particles. These travel forward,
then down and back so that each particle completes a circle. "

Of course, there could be some confusion as to what constitutes the
"face" of a wave and what is the "back". For me, the face is the
frontside of a moving wave and the water particles are moving down
that face. Even though the water rises, the particles in the water on
the face of that wave are falling.

Counter-intuitive, I know.

An excellent animation of various wave motions can be found at:

http://www.kettering.edu/~drussell/Demos/waves/wavemotion.html

The animation of water waves (3rd animation down) clearly shows how
the particles of water behave in a wave.

> And edging on skis with heavy sidecut is an entirely different game than
> edging a kayak (WW or other wise) because sidecut generates a curved edge
> that interacts with the surface to generate turning forces _toward_ that
> side, not away from it.  [I feel particularly unqualified to discuss the
> mechanics of sidecut on snow, inasmuch as I never learned to do parallel
> turns!  Strictly a skidded turn guy, perhaps a consequence of my surfer
> heritage and upbringing!]

My downhill skiing days left with the ligaments in my left knee
somewhat before the onset of "heavy sidecut". I believe that Head
pioneered sidecut with their metal skiis back in the late 60s so that
turns could be "carved" back then but it took a lot more effort (or
technique). The "carving" is caused by shifting weight forward to flex
the tips up and turning the ski (if viewed side-on) into a slight
u-shape. We can't change the shape of a kayak hull by moving weight
back and forth in the cockpit but we can come close to carving if the
hullshape has an relatively sharp edge. Or perhaps we just confuse it
with a "bite". My poor Nimbus is almost certainly doomed to forever
sideslip down the faces of any waves I want to carve turns on. But you
can come very close with a playboat and even closer with a surfboard;
however whether these include more "skidding" than "carving" is
probably a point of debate.

I just love these winter discussions. :)


Craig Jungers
Royal City, WA
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