Question on the amount of force created during paddle stroke

[SUPerstitious]

Hi, I hope this question makes sense...

Does anyone have a general idea of the amount of force (in pounds I suppose) one applies to the paddle during a paddle stroke?

As I pull on the paddle for a stroke, am I pulling 40lbs, 80lbs, 23lbs., 170lbs., etc.?

Obviously this is different depending on body weight, board, paddle, wind, etc., so I am just trying to understand the general range.



Thank you!

[PonoBill]

The quick answer is 20 to 50 pounds. Good paddlers can maintain 15-20 for a long time, 50 is hard.

[NLCHAWAII]

The math works out for a 78" paddle , with a hand grip width of 34" , that to apply 50 lbs of force at the blade tip requires well over 100 lbs of force applied at the lower hand grip location . Bills answer is right on the mark . 20 lbs of thrust generated at the blade can easy be done by most for extended durations , and some individuals can peak out at 50 lbs of forward thrust at the blade tip for very short durations or repetitions . To generate more thrust , in general , is for most only momentary , lasting just a fraction of a second . Different paddle lengths and hand width grips will produce different numbers , but always within a general expected norm .

[DavidJohn]

I'm guessing there are three different areas where there is a force applied here.

A force pushing forward on the blade.. a force pulling back with the lower hand.. and a force pushing forward with the top hand.

What force are we talkin' about here.

DJ

[Rockbottom]

While we're on the subject...  As most of our speed gains are attained ate the 1st 3rd of our stroke,    Would a shorter, more powerful stroke at the catch that quickly wanes before the retrieval be more efficient that a stroke the is relatively evenly applied throughout the stroke?   
      I'm thinking Mabey yes as it would promote a clean release and, given the same stroke rate, a longer muscle recovery time.

[SUPerstitious]

Thank you all for the responses.

DJ,
The reason I asked my question, which may help answer yours about 'what force are we talking', is that I am curious about how to replicate the paddle stroke at home. I am interested in using resistance bands attached to a wall on one end and a paddle or stick on the other.

I was trying to understand if I should be targeting a resistance of 20lbs, 50lbs, etc.

Sounds like I should be targeting ~20lbs, and going for lots of reps at a relatively high cadence.

Hope all this makes sense. Thank again...I love the collective knowledge on this board!

[PonoBill]

20 pounds at the blade tip is about what a good paddler can exert, how they apply that force is a function of their stroke style. There's a VERY long answer to this question that comes at the number from a variety of ways, including of course direct measurement and semi-direct measurement. Our Paddle Pod measures acceleration and velocity of the blade. While we don't know the mass of the water accelerated (which would make it easy to calculate force F since F=Ma) we can get at the mass by measuring board velocity and total mass and calculating the momentum for the board and therefore the water. Mass times velocity squared = mass times velocity squared. Solve for mass and presto! you can solve for force, though there are some problems since the mass is getting accelerated over a short period, but an RMS value for velocity should be close enough. But I didn't.  

Rather than work through that when I was working on the likely forces applied to a paddle I just looked up a bunch of stuff. People have measured rowboat, kayak, rowing shell and OC blade forces over the last hundred years. Twenty pounds works.

[sbsup11]

This is an incredible thread, I love seeing details and quantifiable statistics applied to something that is often just measured in sweat and stoke!

Measuring stoke:

Stoked
Super-stoked
WOOHOOOOO

[hbsteve]

One of the sayings in rowing is:  Acclerate thru the drive.  Max efficiency is when the oars are perpendicular to the shell.  Seeing where a stand up paddle gets max efficiency is harder. 
Today, I had a patch of flat glassy water.  I could actually hear the board changing speeds with each stroke.  Casually, I would say that max effort needs to be applied when the blade is half way between where the blade enters the water and your toes. 
It has been mentioned several times on here to put tape where your target entry is.  What about putting tape where max power results in max speed?
I also paddled past my feet, on purpose.  The board really slowed down.  It was like riding a bike, and having to stop at every light.  And then start up again.
Have fun.

[PonoBill]

It's one of the reasons why a little flex is a good thing for a SUP paddle. No one talks about flex in OC paddles, at least I've never hear it mentioned, and the OC paddle I made from a Ke Nalu blade has all the flex of a fire hydrant.

Flex adds a little hesitation when the catch starts, so you can pull pretty hard. I think it will be hard to increase your effort mid-stroke, and the sweet area of the stroke is already too short.

Your board is moving, so if you stick your paddle in the water and don't do anything it will be at your feet almost as quickly as if you stroked hard. The only difference is the little bit of velocity you added through acceleration and the little bit of slip that a hard stroke causes. Weird to think of, huh. So you push the paddle in the water, and while it's already moving toward your feet you pull to catch. The shaft flexes, delaying power application--paddle is still moving. Now the power application starts and vortexes start to form. Less than a second later you're feather the blade to get it out of the water.

Lots happening.

[LaPerouseBay]

No one talks about flex in OC paddles, at least I've never hear it mentioned, and the OC paddle I made from a Ke Nalu blade has all the flex of a fire hydrant.

Oc paddlers love wooden shafts because of the flex.  Wood has a great feel and cushions the blow.   

[SUPerstitious]

Your board is moving, so if you stick your paddle in the water and don't do anything it will be at your feet almost as quickly as if you stroked hard. The only difference is the little bit of velocity you added through acceleration and the little bit of slip that a hard stroke causes. Weird to think of, huh. So you push the paddle in the water, and while it's already moving toward your feet you pull to catch. The shaft flexes, delaying power application--paddle is still moving. Now the power application starts and vortexes start to form. Less than a second later you're feather the blade to get it out of the water.

Lots happening.

So have you ever timed the duration of the burst of energy used in a stroke?

I paddled today, and what I think I noticed is that the actual duration of time that you are really pulling is not very long at all. When I focused on not pulling past my feet, I felt that the stroke may be "long", but the time is short.

[PonoBill]

No one talks about flex in OC paddles, at least I've never hear it mentioned, and the OC paddle I made from a Ke Nalu blade has all the flex of a fire hydrant.

Oc paddlers love wooden shafts because of the flex.  Wood has a great feel and cushions the blow.   

My Kialoa OC paddle is wood, nicely made, though simple compared to a Malama. I love everything about wood paddles except the weight. Both the Malamas and the Whiskeyjacks are pure art.

[blueplanetsurf]

One of the sayings in rowing is:  Acclerate thru the drive.  Max efficiency is when the oars are perpendicular to the shell.  Seeing where a stand up paddle gets max efficiency is harder.  

In the Quickblade video you can clearly see that the max efficiency (most power and max. flex) happens where the paddle is perpendicular to the water.  If you have good reach and lean forward/ down on the paddle, this should happen well in front of your feet.

[SUPpaddler]

Should be simple to answer your original question.  Just pull your blade against the bathroom scale held at an angle.  I get about 20 lbs for a moderate pull.

Interestingly, this same force doesn't get translated to the board, which is only overcoming about 4 lbs of resistance at a typical effort (going 4 knots)  E.g. see the resistance chart at

http://www.seakayakermag.com/2007/07e-newsletters/December/fastkayak.htm

So, surprisingly, if you tied a string to the back of a paddle board, you could hold a paddler from making any forward progress with the string wrapped around your little finger.  (I know someone will disagree, but how else could you explain the figures?)