# Thread: Physical explanation of pumping down wave face

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## Physical explanation of pumping down wave face

Was wondering if anyone wanted to put the act of pumping down the face of the wave to stay with the wave into a thorough physical explanation as I'm coming up short when I try in my head, mainly in reference to water displacement as the wave breaks and fluidity/speed

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you're pushing against, and displacing, water to the back and sides which helps to propel you forward

I see it akin to tic-tacking on a skateboard or pushing off of alternate skis in an ice-skating fashion to move forward

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wiggle. wiggle. coast

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I see it as the same a pumping in a half pipe on your skateboard. When you get to the bottom of the wave you compress your legs and push off. That forces you up the wave higher and with more energy then you would have if you just let the wave catch up to you. You're higher and therefore have more potential energy for gravity to bring you down with. Add to that that the wave is moving. It isn't necessary to travel up and down the entire wave face. A quick up and down will give the same effect. Aka Pumping. Is this consistent with others' experience?

5. Originally Posted by ewwoodsurf
..That forces you up the wave higher and with more energy then you would have if you just let the wave catch up to you. You're higher and therefore have more potential energy for gravity to bring you down with.
^-This.. It's physics. For example, when you spring out of a bottom turn, your legs are driving the board (creating kinetic energy or rather adding more to what was obtained from the drop) up the wave (which increases your potential energy), which when you go back down, the potential energy is converted to kinetic energy. Similarity to skateboard half-pipe is also a good and valid comparison.

You convert kinetic energy to potential energy then back to kinetic energy, with your legs "adding in" more energy and thus :
Kinetic energy at bottom of wave = Kinetic energy at top of wave + Potential Energy at top
1/2*mass * velocityATbottom**2 = 1/2*mass * velocityATtop**2 + mass* gravity* height

You can build up speed "rollercoastering".

Some refs:
http://topex.ucsd.edu/ps/energy.pdf

http://www.popsci.com/adam-weiner/ar...t-one-dropping

http://www.exploratorium.edu/theworl.../surfsci2.html
Last edited by capecodcdog; Aug 28, 2014 at 12:24 AM. Reason: physics .. not sure if contrails come into play here

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yea to the last two posters, i actually don't mean down the line i mean directly down it as the wave fades, your going to slow for a full cutback to the whitewater, so ya press off the front foot fluidly and efficiently to stay on the wave until the next section comes

7. I think your talking about that weird hoppy bounce thing guys do right? Since your not talking about pumping down the line? If that's the case don't do it, it looks stupid. If you need to hop up and down like a kangaroo to stay on a dieing wave it's probably time to kick out or grab a bigger board

8. Is "pumping" like hunching down a wave. I always was amused by the hopping up and down guys

9. Originally Posted by patgeds22
yea to the last two posters, i actually don't mean down the line i mean directly down it as the wave fades, your going to slow for a full cutback to the whitewater, so ya press off the front foot fluidly and efficiently to stay on the wave until the next section comes
Ankle tweaks

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Originally Posted by DawnPatrolSUP
Ankle tweaks
pumping is ankle-finesse.