Re: [Paddlewise] "Sneaker Waves"

Craig Jungers wrote:

> Basically what paddlers on the west coast of North America need to be aware
> of is wave period. Check offshore wave-rider buoys and if the swell period
> is greater than about 5 minutes be very cautious when paddling in shallow
> water exposed to the open ocean. If the swell period rises to 14 minutes be
> on constant alert.

You mean "5 seconds" and "14 seconds," yes, Craig?

> As I said earlier, there is some controversy as to the exact nature of these
> waves. This is partly because there is often only one wave in what otherwise
> might only be relatively calm water and ocean scientists don't like the idea
> of one wave rising up from nowhere.

I've always heard sneakers explained as the result of constructive 
interference of two waves from slightly different sources, such that a 
single wave (the result of two combined) "jumps" out of the blue.  However, 
there is a more erudite discussion of possible causes here, under "rogue 
waves:"  http://en.wikipedia.org/wiki/Freak_wave

In addition, some feel a wave like Craig describes may be a "soliton:" 
http://en.wikipedia.org/wiki/Soliton  [Googling up "soliton" will lead you 
to lots of very deep stuff -- solitons are thought to be a branch of 
nonlinear science.]

Take your pick.  Stuff like this is hard to pin down, scientifically, 
because it is hard to reproduce in a laboratory (wave lab).

-- 
Dave Kruger
Astoria, OR
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