Re: [Paddlewise] A new way to teach the forward stroke?

MATT MARINER BROZE wrote:

 > Off the cuff, it seems to me that there IS potential energy stored by 
lifting
 > the arms but I don't see any advantage to doing that since the paddle is
 > nowhere near 100% efficient in transferring that energy into forward 
motion.
I'm not so sure about that. The mechanics are complicated, but let's 
simply ask: If the energy doesn't transfer to the force and movement of 
the paddle-blade, then where does it go? The movement of the arms is 
nearly frictionless. Nothing heats up, so no energy is lost.
I think almost 100% of the energy transfers to the paddleblade - but 
from there, I have no idea of the efficiency of a blade pushing against 
the water.

 > Therefore, the more work you put into lifting the paddle the more 
energy you
 > waste because of the lack of paddling efficiency gained in return for 
your
 > efforts against gravity. If I'm correct about that, then other things 
being
 > equal the less you work against gravity during your strokes the more 
efficient
 > you should be.
It is indeed possible that a horizontal stroke is more efficient than a 
vertical stroke. The mechanics and physiology are too difficult to put 
in a simple model. The main reason I consider the vertical stroke the 
best, is that it's been taught by most kayak-instructors and used by 
most paddlers. Once they master that stroke, they're able to keep it up 
for hours and stay with the group, so I think there must be something 
good about it.

 > This is probably one of the reasons why a bent shaft canoe
 > stroke is more efficient than a kayak paddle stroke, less energy wasted
 > lifting the second paddle blade, hand, and arm against gravity and 
more of
 > ones effort going to propelling the kayak horizontally through the water.
Efficiency is one thing; being able to keep it up is another. I tried it 
for myself: I can (in my home, with a paddle out of the water) longer 
keep up a forward-stroke motion than a static position. There might be a 
placebo-effect there: I _want_ to be able to keep it up longer.

I don't know if moving an arm uses more energy than keeping an arm 
steady against a force. To a steel crane, it certainly would be, but 
muscles work differently. They're comparable to a car-engine working 
against the clutch, with the car on the handbrake. Lots of energy are 
generated, but none is transferred to forward motion.
There might be a trade-off somewhere: If you move half of the time and 
rest the other half, you might be more efficient than when you keep the 
arm steady, constantly bearing the weight. I don't know.

Perhaps I step too lightly over what the best stroke is. I could change 
it to: "If you teach a vertical stroke, than THIS should be your 
justification".

Thanks for joining the discussion, Matt. I highly value your expertise.
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