Re: [Paddlewise] Graphite for Bottoms

Regarding scratch resistance and friction reduction-


The original post on this mentioned the reduction of fluid friction.
(Actually, I'm not sure he meant fluid friction, maybe it was sliding
friction on the beach.  I assume fluid friction.)  Many years ago, I did
some research on the drag reducing qualities of visco-elastic fluids.
These fluids were essentially water with the addition of a small amount of
polymer (say 5 to 500 ppm) and great reductions in the drag were noted.  At
that time, it was claimed that the injection of small amounts of this fluid
in the boundary layer next to ships could yield a decrease in the
frictional drag.  Boats could operate at the same speed with less
horsepower expended and less power would be needed to bring hydrofoil boats
to "takeoff".  Fire hoses could discharge more water with the same pumping
power.

So why do I bring this up?  A year or so ago I was having a conversation
with Robert Morris of Brewery Creek Small Boats, who teaches the
construction of skin covered baidarkas, Greenland kayaks, etc.  Robert
claimed that traditional baidarkas paddled faster than many people would
think.  We discussed the fact that the original seal skins might have had
an effect like adding some oil (or whatever) to the boundary layer and
working like a visco-elastic fluid.  Does anyone have any definite
knowledge of this?  Have there been any efforts to use visco-elastic fluids
to increase the performance of human powered vessels?  Does anyone know if
there are coatings that might "ablate" and effect the drag performance of a
kayak or canoe?

Enquiring minds want to know!

Bill Leonhardt
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