RE: [Paddlewise] Fresh water lake paddling

From: MATT MARINER BROZE <marinerkayaks_at_msn.com>
Date: Fri, 24 Jul 2009 15:40:35 -0700
Craig Jungers wrote:

>>>>I did a 4.5 sm paddle yesterday in blustery winds up to about 25kts. The
interesting thing was that even with the relatively short (1 or 2 statute
miles) the wind raised the occasional 18-inch wave with a period short
enough to occasionally wash over my Mariner Express. Surfing downwind was a
blast, however.

However I do have a question about the size of the waves which, I think, are
unusual given the wind speed and the fetch. The lake (Moses Lake) is pretty
shallow with depths of 12 to 20 feet maximum and I was paddling in waters
about typical. I've noticed that winds across this lake tend to produce
steep waves that are close together and seem larger than those conditions
would produce on salt water. Does fresh water react differently to wind
conditions than salt water or is it mostly a result of the shallow water?
Anyone have any thoughts on this?<<<<<<<



Waves going over the bow of an Express you say. My those were short steep
waves indeed! Sort of like going into a steep boat wake I imagine.



Your observations are astute. Fresh water is less dense than salt water and
for the same wind and fetch conditions the waves wilbuild quicker and be
steeper as a result. Also as you already seem to indicate, when the water
depth gets to be about half of the wave length (and less) the waves "feel"
(are slowed by the bottom) so the wave length gets shorter (and therefore the
waves get progressively steeper as the water shallows. The same effect that
happens on a beach that waves are coming into, eventually creating breakers
when the water shallows enough that the waves get too steep to hold their wave
shape against gravity.
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Received on Fri Jul 24 2009 - 15:42:10 PDT

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