Date: Wed, 15 Mar 1995 18:53:13 -0500
Message-Id: <199503152353.SAA10582@postbox.acs.ohio-state.edu>
To: baidarka@imagelan.com
From: hazel.2@postbox.acs.ohio-state.edu (Paul W Hazel)
Subject: Traditional Paddles, Late Entry
Sorry I missed the beginning of this thread;
With respect to traditional blades being unfeathered, if the native peoples
could bend ribs, they certainly could have soaked and twisted a paddle.
Would it maintain its shape after repeated soakings and drying out? I don't
know but I doubt it - at least not without some sort of wood sealant.
Another possibility: They could simply have built the paddle in two parts,
pegged them together at the loom and then lashed it up. It would not have
taken a great deal of imagination to carve the flat faces of the looms in
such a way that the assembled paddle was feathered. And this is the same
type of lashed scarf joint used to assemble the keelson and gunwales of the
boat.
But apparently they never did either of these things. (Although it might
explain how the double paddle was first invented ...??) Why didn't they? Who
knows? Maybe they just didn't think of it or _never_perceived_ a_need_ for it.
As regards the shape of the blades, I think we've missed the real issues.
Whether or not the the modern and traditional blades have the same surface
area is not nearly as important as where that surface area is located with
respect to the overall length of the blade.
First, try this: get a broom and a small heavy object (books, brick, etc.)
Sit on the floor with the brick on your left and grasp the broom like a
kayak paddle, but with your right hand near the very end of the handle as if
an imaginary part of the paddle extended beyond your hand. Now hold your
left hand still to act as the fulcrum and using your right hand stroke with
the "paddle " and try to move the brick. Try this again gripping the paddle
about in the middle, and finally choke right up on the broom and move the
brick.
( Don't bother with a realistic push-pull, rotate-the-torso type of
stroke for this. While it's true that that is the proper way to paddle, that
motion removes the fulcrum point from your left hand and moves it somewhere
into the shifting space located between both hands and your spine - a real
vector analysis nightmare. For this experiment it doesn' matter.)
Which stroke moved the brick the furthest? But which stroke required the
least effort to move the brick? A sweep stroke appears to be the most
powerful because it moves the brick the furthest with each stroke, but:
a) because the lever arm between the fulcrum and the work to be done
is so long, it takes more energy to move the brick, and
b)because the arc distance of the stroke is so much greater due to
the long lever arm, that energy is applied for a longer time in order to
move the brick that extra distance.
Modern paddles put all of the pushing surface as far away as possible where
it can act over the longest distance. Traditional paddles put less surface
at the maximum range and compensate by extending the width of the working
surface into the plane of the stroke, in towards the paddler. This surface
acts over a shorter arc distance but is more energy efficient.
It would also make it a lot easier to fine tune your stroke by adjusting how
much blade is in the water. On a blade with a relatively long narrow working
surface, an inch or two variation in the length of blade in the water would
not have as dramatic an effect as with a modern type where an inch or two of
length may comprise 10% - 20% of the working surface due to it greater width.
I always had a tendency to view the stroke as the mechanism applied to
directly move the boat, but that is not the case. In a strict sense, the
purpose of making a stroke is not to move the boat, nor is it to move the
water. The purpose of a stroke is to move the blade from one point to
another. Because the water resists the movement of the blade, and every
action has an equal and opposite reaction, a force equal to the resistance
of the water is transmitted from the shaft through the paddler and into the
boat, which then moves (reacts)in response to that force.
(I can't believe I may have actually found a use for freshmen physics! I
can't believe I'm actually talking about it on the FIRST DAY OF SPRING
BREAK!) 8-)
Cheers...
Paul Hazel
hazel.2@osu.edu