my aging body says slight flex
I agree with Bnystrom and Caridello on favoring slight flex.
Dave
6lbs is close
So my Uncle, who does chiropractic/physical therapy and is an avid paddler, used a dynamomter to measure how many pounds of force a paddler generates during a kayak stroke (using several paddle sizes/blade shapes) for the purposes of treating injured paddlers/me/himself.
He came with 8lbs as the maximum force he could generate by taking strokes holding the dynamomter and paddle. That would be 8 lbs of force on your hand/arm/shoulder…
I need to ask him about what different paddles he used and if they made a measurable difference (using this technique) in force generated.
Where did he measure the force?
– Last Updated: Aug-08-12 8:54 PM EST –
Just curious. What was the location where the force was measured? Was it between hand and paddle, between paddle and water, or between the paddlers's body and the boat? Of those, the last two would be equal (both are a measure of actual propulsive force), though body-to-boat contact would be very difficult to set up instrumentation for), and the first would be greater (if it was the hand closer to the blade being used, rather than the upper hand). The force between blade and water PLUS the force between the upper hand and shaft = the force applied by the lower hand (one could do a full-scale static demonstration of this with a paddle and three spring scales to show that this is always true).
it’s different
But yet it’s the same.
Same principle applies in lots of products from hockey sticks to fishing poles. But you can’t flex anything until you apply pressure to it unevenly, which would be after the initial paddle plant.
Now I’m wondering about flexy footpedals!
A ton
Any flex and you are a dead man.
That’s why Greenland sticks are so stiff.
thanks
Good catch.
Work associated with deflection is half of what I stated above.
Some arm-chair analysing:
– Last Updated: Aug-08-12 11:07 PM EST –
I think that the "ramping back" of the force applied would happen quite naturally, even with a very rapid stroke (the spring-back could happen in a split second as the power phase ends). The reason I think so is that the blade is withdrawn from the water in pretty much the opposite of the stabbing motion by which it enters, and it leaves the water cleanly. That can only happen if the application of power has stopped. If that weren't the case, the blade would scoop and throw water as it began to "lose traction" and slip as less and less blade area were embedded in the water with power still being applied. Of course the actual action of the paddle when racing might not be completely clean so there may be no absolute statements that apply, so if I'm on to something here, the real situation might be somewhere between your idea and mine.
My Lumpy is quite flexy
And it seems to be the only kayak paddle that allows me to go more than 20 miles for more than one day with out any arm hand or shoulder trouble. Based on that one paddle I’d say flexy is good.
Thanks Bill!
Yup
Bnystrom pretty much nailed that one with an excellent answer for touring.
Yep, sound right
I tend to agree with your analysis.
first one
between hand and paddle shaft.
In that case, …
… the propulsive force is less than the measured force. The easiest example would be if the lower hand were exactly halfway between the upper hand and the center of the blade. In that case, propulsive force would be half the measured force. Keeping hand-spacing the same but decreasing the distance from lower hand to paddle blade would progressively reduce that difference, while increasing the distance between the blade and hand would increase the difference. No matter what though, the lower hand applies greater force to the shaft than the blade does to the water. Perhaps the guy who did this took all that into account. It’s pretty simple, just like the workings of a beam scale.
Amen
Another “Thanks Bill” from me. That little bit of flex feels great.