[Paddlewise] stroke mechanics / technique heresy [was: paddle sizing heresy]

I think blade aspect ratio (length vs. width) has a lot to do with the
difference between greenland and euro paddles, especially in rolling where
the paddle is sliced through the water, like an airplane wing, to produce
lift.  That lift produces drag (called induced drag in aerodynamics) which
is caused mostly by turbulence/vortexes at the wing tips. The greater the
demand for lift the greater the drag. The classic way to gain a favorable
lift vs. drag ratio is to reduce the size of the tips by using long skinny
wings.  Thats why sailplanes have high aspect ratio wings and why greenland
paddles excel when sliced through the water.

The euro paddle is the opposite case.  It has a low aspect ratio and when
called on for lift while being sliced through the water, it  produces a lot
of tip loss/induced drag.  On the other hand, as Ralph H. pointed out, its
low aspect ratio gives it a favorable ratio of blade area to circumference
(lots of area with little circumference) so that it bites the water better
in the forward stroke--especially when you really honk on it--than the
greenland paddle which has an unfavorable ratio of circumference to blade
area. 

Re: the "Technology guides paddle design " thread, I would say that in icy
Greenland waters, rolling, and sculling braces are more important to
survival than quick acceleration in forward strokes, so while materials
(drift wood) certainly influenced paddle shape, I think the Greenlanders'
high aspect ratio blades are as much a function of their use as of the
materials available.  The Greenlanders made a virtue of their necessity.

Clark Bowlen




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