The classical lever has three force points, which are usually called the effort, fulcrum and load, as in this image:
http://currentreports.info/wp-content/uploads/2009/02/firce_class_lever_drawing1.gif
While the above image shows the most common positions of the effort, fulcrum and load points, each of these force points can be at any of the three positions. For example, the fulcrum could be at the end of the lever, the load in the middle, and the effort at the other end.
The canoe paddle seems to be like a lever. There are three force points: the top grip hand, the shaft hand, and the blade in the water.
Some questions:
1. Which of the paddle force points is the effort point, fulcrum point and load point?
2. Can these force points change in character using different paddling techniques? For example, can the fulcrum point change as among the top hand, shaft hand and blade?
3. If the configuration of the force points can change by technique, why or when would a paddler do this? Is one configuration better than the other?
4. Does any of this change if you assume the paddle blade stays at a fixed point in the water or slips?
In considering these paddle lever physics issues, I think we should include relativity but ignore string theory.
Some answers
Question 1. The Fulcrum and the Effort points are both effort points if you are paddling in good form. This is because of body rotation, if done properly, applies most of the force, not the arms.
Question 2. Ofcourse. For example Indian Paddle style verses sit and switch. Indian style uses the bottom hand for most of the force.
Question 3. Use these changes all the time, meaning controling direction or current conditions or obsticals.
Question 4. This may be a joke to many of you but to a new paddler or someone thinking of becoming a paddler these questions could be real.
It is a fact that physics are part of
life,but I think someone is bored. Or a physics geek.
Be dat de “String” theory?
or be it an infinite number o' really pissed off squirrels jus' waitin' fer de right moment...?
FE
In My Simple Mind…
I've simplified Greenland paddles into chainrings on my bike. A longer paddle is a bigger chainring. It rotates fewer times to do the work. A shorter paddle is a smaller chainring. It has to rotate more times RELATIVE to the bigger chainring in order to cover the same distance.
I don't know shit about a canoe paddle.
I've been told that as I paddle away from my buddies that I change to a reddish color.
They should have made their play
when he was immobilized!
I don’t know the answer,
but I’ll bet these guys do:
Nicholas Caplan (2008) A Simulation of Outrigger Canoe
Paddling Performance. The Engineering of Sport 7, Volume 1, 97-105.
Caplan, N. & Gardner, T.N. (2007) A mathematical model
of the oar-blad water interaction in rowing. Journal of
Sports Sciences, 25, 1025-1034.
You can read the first one here:
http://tinyurl.com/yfqso22
(too much math for me)
FE anf tktoo,I have exercised
great restraint today. An obviously new squirrel spent the afternoon in the “red zone”. It was Sunday,so I let him go.
I know he was new ,because there are no old ones.
you must be going fast!
I Guess.
Time gets crazy. My buddies look like they’ve aged so much.
Old News
This topic was beaten to death by Pat Moore and John Winters in the early 90s.
Pat claimed the surface of the water was the fulcrum.
John said bio-mechanical style determined where the fulcrum was.
For Northwoods style paddlers the shaft hand is the fulcrum.
A more efficient style might have the control hand as fulcrum.
Paddlers more attuned to the importance of blade physic will use both arms as struts and endeavor to place the fulcrum at an imaginary point well above the control hand.
Considering the paddle blade
Conceptually, the fulcrum is the force point that doesn’t move. The effort and load points move.
If this is so, and if the paddle doesn’t move in the water (as some say) or only slips a little bit, how could the blade not be the fulcrum?
But the blade does seem (to me) to slip. This could then mean that the blade gets less fulcrum-esque the more it slips in the water.
Contrary to this concept, I subjectively tend to think of my upper grip hand as the fulcrum. I think this even though I know my hand moves relative to my body. However, I don’t think my grip hand moves much longitudinally relative to the hull.
This question may be old (what isn’t?), but I haven’t heard the answer, which seems to be like an optical illusion. There has to be a correct answer in simple Newtonian physics.
Personally, I’m not convinced that technique can change the lever physics, whatever they are.
To clarify the topic, I’m only talking of the lever physics during the power phase of the stroke, not the correction or recovery phases.
tbone, thanks …
… for taking the time to post those research papers.
I read the outrigger paper you linked, but it doesn’t address the paddle-as-lever question.
Based on its title, the paper on rowing probably addresses the lever issue in the case of oars, which is probably a simpler case than the canoe paddle. I’ll see if I can find it online.
interesting question indeed,
also because the answer could tell us something about the ideal paddle length
and the ideal spacing between the hands.
So far I haven’t found a satisfying answer too, because paddling is so complicated:
my paddle blade moves a little backwards through the water
my lower hand moves backwards and
my upper hand moves forward but with a downward force…
Fascinating. Thanks!
Further complication?
And where does torso rotation fit into this?
Jim
“Ideal” varies with…
… all the other variables, so what is “ideal” depends on all the rest.
The major paddle types are all trade-offs, each approaching the problem a little differently*, and which set of trade-offs fit your other variables is totally dependent on you and your other specifics.
-
- Look at the stop motion photos (great because they are at speed, not from a stop or getting up to speed), where it’s obvious there is a point that hardly slips back at all (or even can go forward with wing), and that the tip describes and arc through the water around that point. Now think about how the different paddle types deal with this. At the relative extremes (with kayak paddles anyway) you have the wing and GP (really a different type wing). Basically we are talking condensed blade area vs spread out blade area.
With wing (and EP with great technique) you want to minimize the arc by keeping the paddle vertical for as much of the stroke as possible. When I say vertical I mean as seen from the side (you can do as you please with high/low angle BS as seen from the front). Top hand crosses at same level as you rotate and top hand does not push down. You also avoid carrying the stroke past your hip (gets out of vertical from there). Rotation maximizes power and lengthens the stroke while also enhancing the ability to keep the blade more vertical in the water. The verticality (largely via level top hand) reduces pushing water down or pulling water up which both waste energy and minimize leverage (area relative to force vector).
With GP you actively work the arc during the stroke by punching down and across with top hand, taking advantage of the canted blade for vortex control, and getting kick from the later part of the stroke too. Because you are working the arc vs avoiding/minimizing it, the core action is a bit more of a side crunch than a more vertical axis rotation.
Aleut sort of splits the difference, at least the way I use mine (GP Catch, some EP/Wing initial rotation and a little flare, then going to a delayed punch/crunch/GP finish).
All are quite effective, but each in a different way. Choose according to your needs and preferences, not to seek some “ideal”.
Sorry, can’t really speak to canoe paddles, but they vary in blade area in similar ways, physics is physics, and people are people so same stuff I’m babbling about should apply.
- Look at the stop motion photos (great because they are at speed, not from a stop or getting up to speed), where it’s obvious there is a point that hardly slips back at all (or even can go forward with wing), and that the tip describes and arc through the water around that point. Now think about how the different paddle types deal with this. At the relative extremes (with kayak paddles anyway) you have the wing and GP (really a different type wing). Basically we are talking condensed blade area vs spread out blade area.
Think in terms of…
... resultant force vectors, blade face realtive to same, etc. Hit on a couple bits of this above.
More simply, just think about planting the paddle and levering off it as you drive the kayak (canoe, whatever) past it instead of pulling on the paddle and dragging the hull around with it.
Rotation is a component of more effective levering, not part of better pulling!