Subject: Re: [baidarka] Paddle Dynamics 101
From: RCH3149@aol.com
Date: Wed Jun 20 2001 - 11:27:32 EDT
Joe,
What kind of paddle do you use? Have you had a chance to experiment with a Greenland type blade with the upper edge of the blade tilted forward during the catch?
In my own practice, I detect strong similarities between the path through the water of my slicing Greenland blade and of a wing paddle blade in action. The most marked difference between the two is that the former reverses leading and trailing edges at some point during the stroke, in order that it can be sliced out of the water at the finish.
By the way, once I had moved on from my old shovel bladed paddles, for a long time I felt most comfortable paddling with the wooden Bending Branches "Journey" model, happily slicing the relatively high aspect ratio blade in and out of the water. Then I starting to paddle with a Greenland blade and, converts being the worst (:-), see no reason to go back.
A few weeks ago, paddling alongside a fellow with a beautiful Werner paddle, we decided to trade propulsion sticks for a while. I found that the shape of the Werner blade dictated a completely different stroke and effectively prevented me from slicing. I surmise that the Werner blade shape is indeed optimized for pure drag operation (which you, Joe, appear to ascribe to all paddles), whereas the convex profile of the "Journey" was already suitable for me to introduce a component of lift by effecting a different path of the blade through the water.
When I paddle with a slice, I leave no or at most small surface vortices behind, which suggests that I lose relatively little energy to swirling water (at least to that manifestaion of energy dissipation). Without complicated testing I cannot prove it, of course, but my experience is that using a (well profiled!!) Greenland blade for touring, I seem to manage to direct a very pleasing proportion of my input energy to forward motion -- for the same speed and distance I feel (the comparison is purely subjective!) less tired using the Greenland blade than using drag based technique with other blades.
The absence of such vortices also suggests that the slicing component of the blade path takes place at a low enough angle of attack to prevent stall. I can certainly make the blade stall by hauling back hard enough (hey, I broke an oar once during a rowing race by hauling in anger :-), but find that I do not cover ground faster in equal measure to the increased expenditure of my energy. If I want to go faster, I increase the cadence ... I stress again, that all this aplies to my normal touring speeds, not to sprint racing!!
I should also mention that, if I need immediate high acceleration, I merely bury the blade as far and as vertically as I can and haul back brutally with no regard for wasted energy.
There has been a lot of discussion on the theory of lift and drag as it might apply to paddling recently. Has anyone else tried to compare in practice the most "comfortable" techniques appropriate for different high and low aspect ration blades with a view to emphasizing lift over drag and vice versa?
[Aside:
I saw a very interesting technique the other day, in which the paddler twisted the torso (as usual), but in addition leant forward so that on every third half stroke he could put in one very strong power phase by pulling backwards also. Due to the rythm he alternated the power phase left and right. I had difficulties keeping up with him (he seemed to draw away a few inches on every "power stroke") until I tried to adopt the technique myself. He and I were both using Greenland type blades, while a third paddler was using a Werner. All three of us were perfectly comfortable with our individual techniques and paddles and this was by no means a test of the "superiority" of one method of propulsion over another.]
Best regards,
Ralph
Ralph C. Hoehn
Ralph@PouchBoats.com
www.PouchBoats.com
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