Some thoughts on water flowing over a paddle- by Robert Stehlik

Quickblade’s Jim Terrell recently came out with an excellent video breaking down the SUP stroke with high tech video analysis. .
The video analysis clearly shows that on longer raceboards at cruising speeds, good paddlers plant the paddle and move past it.  It shows Rob Rojas in slow motion, planting the paddle, applying power with the shaft bending and no visible “slippage”, the blade merely rotates at the waterline. With his forward momentum, he actually pulls the blade out in front of the spot he planted it.  To me this clearly shows that once the blade is planted, the water is compressed against the face of the blade and there is very little “slippage” or backward movement.  This made me think more about how a paddle blade moves through the water.  I’m not a scientist or paddle designer but just want to share some of my thoughts.
When people talk about paddle blade design they usually explain how the shape and design of the blade moves through the water, visualizing how the blade face gets pulled backward through the water.
In reality, during an efficient race stroke, there is very little movement of the blade once it is planted.  The water is compressed against the face of the blade and if the force is applied at the right time in the right dosage, there is very little slippage or movement of the blade backwards, it is effectively planted in the water, not moving through the water.
So, most of the movement of the blade through the water occurs when the blade is sliced down into the water during the catch and when it is pulled out of the water during the release.  In both cases, the paddle moves sideways, or tip first with water rushing past both sides of the blade.
When you think of it this way, most of the water flowing over the paddle is not flowing over or past the face of the blade but moving sideways, during the catch and release.  When designing a paddle the concern should be to make the sideways movement during catch and release as smooth and efficient as possible as this is the way the paddle travels through the water the most: slicing into and out of the water.
Instead of looking at the face of the blade, look at the edge/ tip and side profile of the paddle as that is the direction the blade moves through the water mostly.  It seems to me that a thin, flat blade should be most efficient slicing through the water sideways, while paddles with big spines, concaves, curves or other features designed to “catch” more water will only disrupt a clean sideways entry and exit.  It seems that a mild dihedral close to the waterline will not disrupt the waterflow during entry or exit much but maybe Kialoha is onto something with their completely flat, relatively thin blades.
It also means that it does not matter whether you put a sticker on the face or back of the blade, the sticker edge might cause a tiny bit more friction on either side during catch and release, but should not make a difference during the power phase.
So what’s up with those “magic” golf ball dimples on the face of the Quickblade elite racer blades? Some people seem to think they are designed to “hold” more water…
Read Full Article on Zen Waterman

Other Articles on Zen Waterman on interest:

Paddle Technique – Reach and Catch

Paddle technique – Power Phase

Paddle technique – Stacking shoulders

 

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