What is the science with blade shape?
– Last Updated: Dec-02-07 9:17 PM EST –
Could you give some examples, Roy?
Thanks.
there’s
not any real anything about blade shape. I just have certain preferances. as does everyone else.
I just mentioned that given 2 differant paddles.
one is bent and one is strait.
I would pick the one that comes with the blade style that I just happen to prefer. rather than chose using the bent/strait configuration as the determining factor.
that is all I ment …no rocket science here…just “what I like” 
Best Wishes
Roy
Paddle length
Why does the sizing chart usually suggest shorter bent shaft than the straight shaft?
http://www.nrsweb.com/shop/Bending_Branches_Paddle_Sizing.asp
Paddle length
The length of the paddle shaft is based on the distance between your arms/shoulders and the water. The closer your arms are to the water, the shorter the shaft will be to maintain proper biomechanics. Hence if you are kneeling with your butt on the seat (traditional 3 point position) or more extreem sitting on your heels, the paddle shaft will be shorter than if you are sitting up on a seat. Charlie Wilson, I’m sure can give a more thorough treatise on this subject.
Marc Ornstein
Dogpaddle Canoe Works
stance and paddle selection
To paddle efficiently, i.e. arrive faster or feel better afterwards, we need to consider and compromise between 3 kinda mutually exclusive things: paddle physics, bio-mechanics and a hull that is quiet in the water.
Lets just assume we all stack our hands for a vertical paddleshaft and paddle parallel to the keel line, not the rail. Doing either makes forward strokes into sweeps, which turn the boat.
John Winters tells us the paddle is only efficient withing +/- 10 degrees of square to the stroke. [Yeah, almost everyone carries the blade too far aft which changes the mean elevation of the waterway but does not contribute to forward motion.]
Each paddle has it’s ~ 15 inch “sweet spot” where the blade is in that +/- 10 dg window. With a straight it is farther forward relative to our bodies and on the boat; mostly in front of the knee. With a 12 dg bent the window is further aft; pretty much knee to mid thigh.
When we kneel, we can torso rotate and reach to a catch ~ 20 inches forward of our knee. We are unwinding that rotation, using the adductors, extensors, latts and triceps for maximum power through the 10dg window. When the paddle travels aft to the knee, take it out and recover to another forward stroke. [Correction later]
When we sit in a canoe seat with our legs on footpegs, we loose torso rotation because we are now rotating from the waist instead of the knees.
As we cannot rotation and reach as far forward, straight paddles 10 dg window is shortened and forward strokes become less effective.
The simple solution is to bend the paddle to move it’s sweet spot aft; to within the paddlers easy reach. Trial and error over ~twenty years has shown that a 12 dg bend works best for sitting paddlers. Those 5 and 7 dg bents are for some stance in the boat between kneeling and sitting, we just haven’t identified the position yet.
Sitting paddlers should rotate and reach and use the same muscle groups as kneeling paddler, but, the stroke is closer to the paddler, from just before the knee to mid thigh. That is one reason bents size shorter than straights. The stroke is shorter, which allows a higher cadence, and the range of motioin is truncated. Note that by definition, a 12 dg bent is outside Winter’s window and wildly less effective for draws, prys and corrective strokes.
That is why many of us are best served by tripping with a bent and a straight - we can change where it hurts. On the other hand, some boats seem to be dedicated to sit and switch or kneeling technique and hence, dictate our stance.
The Quiet Boat in the Water is a third efficiency point. If the canoe rolls or pitches or yaws, we alter laminar flow along the hull and significantly increase friction. All bad things.
In a tandem, with two people paddling on opposite sides, in cadence and parallel to the keel, little if any correction is required. [When a tandem canoe yaws to the bow paddlers side, the stern paddler is sweeping by 1. Not stacking his hands, 2. Paddling along the rail, or 3. carrying his paddle behind his body.
Solo is harder as we have a single propulsion source that is off-center. Sitting paddlers usually switch sides every ten strokes to induce slight, cyclical yaw.
Kneeling paddlers can correct after the power phase of the stroke by a thumbs up pry, a thumbs down J or loading a sliced recovery. Many WW paddlers and a few flatties use an uncorrected forward stroke, setting the hull to carve onside, countering the yawing forces of the stroke. The boat flies, but one needs a fair amount of hull and paddle sensitivity to get the trick to work.
I don’t honestly know, although I…
…did when I got it. Superlight, in any event, lighter than any other double I’ve hefted.
In between sizing
I am sitting. I am right in between 54 and 57 inches for a straight shaft according to the sizing chart. Do I take the longer one or the shorter one?
final selection
Kinda depends on your personal paddling style. I use cross strokes when kneeling and would select the longer straight stick.
Sitting, which means using a bent, will find me selecting a shorter shaft. I’m not going to use cross strokes with a bent, and as the stroke is close to my body, no need for the longer shaft.
don’t know how long a paddle should be
– Last Updated: Mar-22-08 9:51 AM EST –
But I do know what seems to work best for me (and some others too). Also I know when explanations about the right paddle length are not correct.
My torso rotation whether kneeling or sitting is about the same.
Sitting seems to allow me even better rotation...
Therefore I doubt that kneeling or sitting paddlers need very different paddles/paddle lengths. If they do need a different paddle/paddle length, it is probably for another reason than the difference between sitting or kneeling.
Also the position or angle of the blade is not really the discerning factor. It is direction of the movement of the blade through the water, and the direction of the lower arm and the position of the lower hand that is important.
The more vertical the lower arm is and the lower the lower hand is, the more you are pulling yourself downward towards the water instead of forward.
In that view I think it is perhaps the more upward forces from the bent-shaft paddle that neutralize the downward forces better? Is the best explanation I can come up with.
Ending the forward stroke when the elbow of your lower arm starts passing your body, is in my view better advice than designating a reference point for the paddle blade in relation to a body part, because the 'elbow advice' takes more or less body rotation in account.
food for thought
mechanics of paddeling
Thanks for the detailed and comprehensive description. Lots to consider vs dip and pull.