Re: [Paddlewise] Greenland paddles

John,
See below for a few specific comments of mine.

On Thu, 23 Jul 1998, John Winters wrote:

> Julio wrote;
> 
> ->
> >The feather is one reason. If you try the low Greenland stroke with
> >a feathered paddle you are likely to ruin your wrists.
> >But the main reason why it is difficult (I am not saying impossible) to
> >do Greenland style paddling with a modern blade is that the Greenland
> >paddle has a symmetrical hydrofoil shape --a wing-- and modern paddles
> >do not.
> 
> My modern blade is not feathered and I know that some builkders don't mind
> making unfeathered paddles. Why can't the modern blade be made with an
> airfoil shape?

Modern blades could be made with a symmetrical airfoil shape, but
apparently they are not. Modern wing paddles have assymetrical airfoils,
but this shape makes bracing and rolling much more difficult. This
difficulty might be a function of problems with controlling the angle of
attack during the brace and roll as much as it is a function of some
inherent problem with assymetrical foils. It is extremely easy to control
the angle of attack with a Greenland paddle, because the paddler is ALWAYS
grasping the blade itself to some degree.

> .
> >
> >Another thing that one has to watch out is that true Greenland paddles
> >have a short shaft, and the paddler is always partially gripping the
> >blade directly, there is no confusion on the position of the blade
> >at any time. Commercial Greenland paddles have a long shaft and the
> >paddle puts his/her hands in a round portion of the paddle. That can
> >make rolling pretty confusing, and so is bracing and paddling affected.
> 
> Anyreason why a locator can't be put on modern shafts or that the shaft
> can't be oval?

No problem here, and this is often done. However almost all cases of this
do not have enough exaggeration in the indexing to make it really
effective. George G. and I both modify our modern paddle shafts with a
strip of autobody moulding and tape to make the indexing much more
effective.
 
SNIP

> >
> >> And in response to Dana:
> >> I am confused. If the Greenland paddle slips through the water more
> easily
> >> then isn't more energy lost? If so, why does it use less energy? Seems
> to
> >> be contradiction.
> >
> >The issue is not whether or not a paddle uses more or less energy,
> >is how it uses it.
> 
> I don't understand this.

The issue here is confusing because there are really several issues
involved. One is that 'efficiency' needs to be broken down into absolute
power output from the paddle, versus the ratio of paddler power input over
paddle power output, where the latter is my definition of paddle
efficiency. The former is of interest to flatwater sprint kayakers where
speed is all that matters, the latter is of interest to recreational and
marathon sea kayakers where stamina and efficiency over long distances are
key. This issue is further complicated by the fact that sprint kayakers
and racers are paddling their boats in a different hydrodynamical (is
there a better word?) regime than recreational paddlers. Racers paddle
their boats in a regime where power output necessary to maintain a speed
is a non-linear function of the speed itself, so every last erg of power
is critical. In contrast, recreational paddlers operate in a linear
regime of power vs. speed, and small differences in power output of a
paddle are trivial. Therefore the differences in power output of a
greenland vs a modern paddle are indeed trivial. We shouldn't waste
our time arguing this. What is more important by
far, is the energy expended by the paddler in producing that output
(efficiency as i've defined it), and here is where I would argue that the
variety and style of Greenland paddle strokes is superior to that of a
modern paddle. See my previous post for more explanation of this.

 > 
> >
> >It might be phychological; faster and shorter strokes with less force
> >are probably more comfortable for the spirit of many humans. Being calm
> >and relaxed conserves energy, and paddling with a succession of
> 'umpfs -umpfs'
> >(pulling hard) drains mental and physical energy together.
> 
> My question was why a modern blade could not duplicate the characteristics
> of the Greenland blade. Is that not possible or is it impossible?
> >

I really doubt that the problem is psychological, although it may indeed
have a relatively minor effect. 

> >Again, modern paddles lack the symmetrical foil shape. You can try
> >to paddle with a model of a Greenland paddle without the foil shape
> >and find out that it does not take you anywhere.
> 
> Why doesn't it work if it is flat?

Technically speaking, even a flat plane is an airfoil, as is a cylinder or
sphere. However the angle of attack window which does not produce
turbulence is much much smaller for a flat plane than for a foil shaped
paddle. A greenland paddle makes it much easier to maintain laminar flow
and therefore maximum lift during the entire stroke. I don't know how easy
this is with a flat blade, or whether it is practically possible.

 > 
> >I am under the impression that Greenland paddles work like wing paddles
> >but flying through the water upside down (they dig down as they enter
> >the water, and that force is used with the torso rotation to aid
> >in pushing forward)
> 
> Sorry but I am dense and don't comprehend.

I don't comprehend either. My understanding is that a greenland paddle
works identically as a modern wing paddle, however because of the
symettry, it is possible to generate lift while the paddle is digging down
and also while lifting up by slightly altering the angle of attack.

 >
> > >The Greenland paddle flies through the water, the lift component that
> >is used to push the boat forward is more important than the side
> >component used by the drag of the blade alone.
> 
> In other words you are saying that th Greenland paddle works like a wing
> except in a horizontal direction instead of vertically?

The greenland paddle is a wing, period. However some of the strokes used
have a different form than modern racing wing technique, and therefore the
lift and drag vectors may be different.

 > 
> >
> >A good scientific way to improve Greenland paddling would probably be
> >to experiment with NACA foils, and decreasing angles of attack towards
> >the ends, like airplane propelers. Maybe one could get to the most
> >efficient Greenland paddle for Greenland racing, if there ever is
> >that discipline.

Actually, I would be interested in how a greenland paddle would work in a
marathon kayak race.

Well,
That is all for me today. Cheers,
Kevin

> 
> Suppose someone said that they had done this test already and discoveredf
> it was not valid?
> 
> Cheers,
> John Winters
> Redwing Designs
> Specialists in Human Powered Watercraft
> http://home.ican.net/~735769/
> 
> 
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