Re: [Paddlewise] speed with versus against the current

John Winters wrote:

(Donna wrote:)
> >When I turn around and
> >head to shore the way I came but with the wind at my back, I feel awkward and
> >have a hard time keeping on a straight course.  Is this difference because it's
> >a lake rather than a river?
> 
> The reasons for this are rather complicated. Maybe this much simplified
> explanation will help.
> 
> The water molecules in a wave travel in circular orbits. At the crest they
> travel with the wave but in the trough they travel in the opposite
> direction. When paddling down wind the bow might be in the trough while the
> stern will be on the crest (also vice versa) . If there is any angle
> (almost always) there is a turning moment on the boat causing it to veer
> off course. This is aggravated as the boat travels more closely to the wave
> speed (period of encounter) when the forces have more time to act on the
> boat. Against the wind the period of encounter is very short and the
> relative flow is always in the same direction so there are no (or minimal)
> turning moments.
> 
> The only time being in a lake or river would make a difference is when the
> waves are due to the river flow rather than wind driven waves. Waves cause
> by velocity variations in a river behave differently from waves caused by
> wind.

The above (response to Donna) is correct, as well as qute lucid --
thanks, John.

-- 
Dave Kruger
Astoria, OR
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