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From: <FoldingBoats_at_aol.com> subject: [Paddlewise] stroke mechanics / technique heresy [was: paddle sizing heresy] Date: Fri, 11 May 2001 18:40:23 EDT · This archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:22 PDT

> It's interesting that avid paddlers feel that the paddle 
> blades don't slip.  I've watched many canoe and kayak paddle strokes trying 
> to understand exactly what's going on. They slip a lot!  Paddle with part 
> of the blade above water and watch how far the vortex travels from the 
> blade while it's in the water (don't confuse it with the persistence of the 
> vortex after the stroke is over).  That's paddle motion.  The problem is 
> that you have a hard time separating the relative motions of the paddle 
> compared to the kayak, you compared to the water and the paddle compared to 
> the water. All other things being equal, I'd not discount the significance 
> of blade size.

Ralph Hoehn: Blade size and shape, as well as, among other things, the ratio 
of the circumferential length of the immersed blade to its area will all have 
a bearing on the ratio of slippage (energy lost to the forward propulsion of 
the boat) to increased kinetic energy of the boat. Slippage is an inevitable 
consequence of relying purely on the drag of the blade of the paddle to 
achieve forward motion of the boat.

A gentleman in Germany recently reported that video footage of wing paddles 
in action showed that they actually traveled through the water some way in 
the same direction of the boat. Did not see the footage, have no experience 
with wing paddles, cannot judge myself. The point is that rather than relying 
on drag to produce thrust, these paddles are designed to create a large 
component of lift (somewhat similar to wings ... or perhaps hydrofoils would 
be a better parallel).

However, having been part of some drawn out discussions on how paddles can be 
used to propel boats, it appears to me that there is a stubborn general 
misconception that drag (of the blade through the water) is the only way to 
produce thrust, completely ignoring the possibility of achieving a component 
of lift by shaping the blade AND the immersed path of the blade accordingly. 

The forward tilt of the upper edge of the blade at the catch, used by some 
practitioners of "Greenland technique" (however this may be defined), 
produces a slicing motion. Furthermore, Greenland style blades scull very 
easily (submersed as well as on the surface!), producing lift. So it would 
seem sensible to investigate whether this phenomenon can be useful in 
enhancing the way, with which the energy exerted by the paddler can converted 
to forward motion of the boat (I resist going into long, intricate details, 
please excuse this gross simplification of concept and terms). 

My own ongoing (casual) experimentation with relatively high aspect ratio 
blades, not intentionally specifically designed for a lift generating stroke, 
suggests that introducing at least a significant component of lift has great 
potential (and is probably done consciously or unconsciously at least by some 
"Greenland style" practitioners). 

Anecdotal evidence: Paddling, using my hybrid stroke mechanics, a supposedly 
sluggish single folding kayak next to a sleek and sexy "sea kayak", the 
latter propelled by a reasonably experienced paddler, I found that I had no 
trouble keeping up. On the contrary, clearly the ease, with which our boats 
kept pace and traded the lead, impressed my fellow partner sufficiently to 
remark without prompting that I got "a lot of speed out of those blades". 
Wind was up to 15 kts with short, steep waves 18-24 inches (short fetch) on 
the port bow going out and on the starboard quarter coming home; neither 
paddler was in a position to have to brace at any time, neither boat deployed 
a rudder and course correctional strokes appeared evenly matched -- in other 
words both paddlers were more or less free to concentrate on their forward 
drive. (I will spare you a list of further similar situations other that to 
mention that they have occurred.)

I am NOT suggesting that all drag based technique be banned, all low aspect 
ratio blades be scrapped or that anyone give up whatever paddling style they 
are comfortable with, but I do find the concept of introducing lift into the 
equation intriguing and the apparent results of my own experimentation 
encouraging.

Please comment!

Best regards,
Ralph

Ralph C. Hoehn
Ralph_at_PouchBoats.com
www.PouchBoats.com

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