Paddle blade shape - why?

Look at the Werner Paddles page here:

Compare the “play” paddles, the three on the bottom, with the “river running” ones. Why would the river running blades have the Bottom edge bulge-down like that? Why not all have the slim angled profile that the play paddles have, what I feel is a lot more ergonomic for a close catch at the beginning of the stroke? The only reason I can think of is if the paddle is only half-submerged, a highly asymmetrical paddle would have a tendency to try and rotate around the axis of the shaft, thus messing-up your stroke and stressing your wrists to keep it in line. But then, if your paddle is only half submerged, you don’t have much resistance in the water anyway and your strokes would more often than not be with fully submerged paddle, so does it matter? I hate fat bladed paddles that require you to keep your hand a fist or more away from the hull to avoid hitting the boat with the paddle - just does not make sense to me, when I can have a paddle that would let me slice right next to the hull for a more efficient stroke… Thoughts?

Asymmetry reduces torque.

Yes but…

– Last Updated: Jun-12-12 1:14 PM EST –

ANYONE can see how a standard touring shape provides the same surface area on each side of the blade if totally submerged, and even when partly submerged at the angle at which you usually see these paddles used. In fact, that's exactly the type of blade shape Werner used to illustrate this concept in the write-up you provided the link to. But look at the OTHER asymmetrical shape referred to in the original question. At a glance it looks like it would be better suited to a higher-angle stroke, but if you look more closely, it appears that no matter where you "draw the line" between submerged and non-submerged portions of the blade, or even if the blade is totally submerged, there's more blade area below center than above. Maybe it's an illusion, but if that's the case, why is it so obvious that the blade area is equal above and below center on a standard asymmetrical blade, but not the case with those river-runner blades? I say the O.P. is asking a legitimate question.

Opps, my terminology is wrong. The three on the bottom are "play" paddles, and those are the ones that appear to have significantly more surface area below center than above center.

Contact Werner
Why don’t you ask Werner about their designs. Since they designed the paddles I’m sure you should get an answer.

River foamy stuff

– Last Updated: Jun-12-12 1:00 PM EST –

Paddling thru foam may need "bigger" surface area

A larger portion of the blade shape
at the upper tip, (above the center line)
may allow a paddlers to get instant bite
upon the the catch.

Good observation about the surface

– Last Updated: Jun-12-12 5:07 PM EST –

assymetry... Upon a closer look, indeed the bottom part seems to have bigger area no matter how we look at it and especially if not fully submerged... I assume the asymetry is to allow a more ergonomic position under the boat for a more vertical close to the sides stroke. But I would have thought that the surface area on both sides of the centerline should be about equal or else there will be uneven torque... Could be an optical illusion...

When every stroke counts, one dips the blade deep and fully, so asymetry of shape does not matter while uderwater. So no torque equalization benefit. In foam the good water is again deep, so I do not see how a bulge on the top would provide instant bite either - if anything, a wider bottom area is what provides more initial bite. In fact, I think this might be the explanation: to have a strong initial bite, have wide bottom/end of blade. To have a short overall blade while maintaining the desired surface area (for quick moves) it must have a wideened upper half too. To have ergonomic entry near the hull with any stroke and under it during a vertical stroke - it is this precise shape that does all three, while maintining a torque neutrality.

Effectively, imagine a rectangular blade that is attached to the shaft along the diagonal of the rectangle, and we get these paddles...

So, that said, it seems these paddles are very good when used with a good catch phase (fully submerged) but not good for "relaxed" paddling with only half the blade dipped in water...

I don’t see why you think that
asymmetry would not matter once a paddle is totally submerged. At least the designer-maker has to be careful about asymmetry, because the closer and more distant parts of the blade are traveling different distances.

I can’t figure out why the playboater paddles are the way they are, but for river running, Scott Shipley competed in slalom with paddles provided by Werner. Those paddles were straight shaft and the blades were asymmetrical. Scott notes in his book that he is not that “high angle” and keeps the paddle shaft at about 45 degrees to the water surface, so that it provides support in very squirrely, turbulent water during a race.

Maybe I was not clear

– Last Updated: Jun-12-12 7:07 PM EST –

I meant that it would not matter if a paddle is symmetrical or not in terms of shape, but it better be symmetrical in terms of grip on the water on both sides of the shaft. That equal resistance would probably be achieved through having equal area on both sides of the shaft, even if that area is not distributed symmetrically in terms of shape. Whether a rectangular blade is attached to the shaft along its diagonal or along its centerline that divides it in two equal rectangles, it should not matter, of the entire blade is under water...

I suppose the somewhat circular path through the stroke might have some effect relative to the shape too, but I can't visualize exactly what that might be...

Oh, and looking at the fiberglass cousins of the above linked carbon paddles from Werner, it looks like they are fairly symmetrical in terms of surface area on both sides of the shaft, regardless of how that area is distributed on each side of the shaft:

Probably the light being clearer in these pictures shows the (a)symmetry better...

And now, the new Lendal has it too
The XRANGE Lendal blades (at least the touring shown currently) have that down-drop shape now too:

I wonder how these paddles feel if not fully submerged in the water… I suppose, the crank on the shaft would hide to some extend the assymetrical forces that one would experience in such situations. Straight shaft users - better have a full deep catch before you pull -:wink: