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

Hi Peter,

> Re your method and mine. It sounds as if both would work. They probably
> each have their own difficulties. But before getting into weighing the
> arms at appropriate angles as an alternative and before doing any more
> calculations, I need to focus on understanding the movement better.

I think you guys are heavily overcomplicating things. I think that only 
the "weight" of your hands matter. I put "weight" between quotes, 
because actually we're little interested in weight or mass. We're 
interested in _force_. After all: Energy = distance * force. We're 
really only interested in the _force_ that your hands and paddle 
generate when going down and the force that's needed to counter that 
force to move your arms up. That force is shown when you put both hands 
and paddle on a scale.

A more direct measurement is shown in my last video (the link again, for 
convenience: http://www.youtube.com/watch?v=io6S_gRxk8c ) Since those 
measurements confirm the energy output (lower force * higher distance = 
same result) I have little reason to include more even indirect and 
complicated measurements.

> Something that is a concern is the transition of an arm from high to low
> before the paddle enters the water. I can accept that a falling arm and
> paddle are converting their potential energy to kinetic energy prior to
> the blade entering the water, but the falling arm has to unbend through
> a right angle and contribute to supporting the paddle so that it can
> spear into the water on the other side of the boat at an appropriate
> point. So no matter how relaxed the arm, work is being done by
> supporting forces in the torso, upper arm and forearm segments against
> the falling weights of the forearm amd paddle. This will use up some of
> the converted kinetic energy that would otherwise have contributed to
> the blades acceleration as it enters the water.

Sorry Peter: You've lost me. What arm is the "falling" arm, and why 
would it have to unbend? Should it be bent in the first place?
>
> On the other hand it allows simple and accurate measures of
> the potential and kinetic energies associated with a complex movement by
> breaking them into component segments and the corresponding
> displacements and masses.

When you start including bending of arms and weights of different 
arm-parts (that start being interesting when you start including 
acceleration, which we haven't discussed so far) things get very 
complicated very fast. I could perhaps still perform such calculations 
(it has been 20 years), but the chance of errors would be too high to be 
of any value.

> Wrist movement is a valid consideration but Ibve managed to determine a
> feather angle and paddle length that works with the vertical stroke to
> greatly reduce or remove my need for wrist cocking and so far havenbt
> experienced any strong wind issues b thatbs a separate discussion.

I'm afraid that discussion would be like the vi/emacs-wars and the 
heated discussions about what soccer-team is "best".

I've made my choices. I program in Vi, I have no interest in soccer, and 
I use a wing-stroke with a feathered paddle.

By all means, continue any of those particular discussions, but I choose 
to get the popcorn, sit back and enjoy the show.

Niels
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