whooping, hooting, yodeling
Ahem…
You’re completely overlooking the ::::::flow from tectonic drift.
{_}
From what I read and from what I understand of this and your previous post, I can’t see your argument making any sense. Furthermore, I can’t see how surboard wake dose anything for your hypothesis. A wake from a boat pushes water away because the boat is moving faster than the current, thus pushing the water away from the centerline as it moves through. The “Reverse wake”, if i may coin that term, is caused by the board going slower than the wave it self, creating a low pressure area, or pocket of air behind the board, which is rapidly filled via diffusion. Think of an obstruction, such as a rock or tree stump in a flowing river, behind the obstruction water is caving in…basically what I am saying is…whats your point?
Feel free to retort and correct me if I am wrong in my assertion.
“obviously” gravity is the opposing force
can we just assume that its always there, as it is.
i agree with roy
always have
its the same freaking thing just worded differently
your still harnessing kinetic energy using gravity
its both man
wave energy and gravity and rider muscular input
sort of like a holly trinity
you guys have been saying nah
its all gravity
its like skating or snowboarding
when obviously
its not
becuase a wave
unlike a half pipe or mountain is moving water
you dont say i gonna go surf some gravity toady
or
hmm the gravitys not very good today
Quote:
“obviously” gravity is the opposing force
I dont know…havn’t you ever seen Silver Surfer? There is no gravity in outer space, yet he is surfing…How do you explain THAT?
Quote:
“obviously” gravity is the opposing force
can we just assume that its always there, as it is.
i agree with roy
always have
its the same freaking thing just worded differently
your still harnessing kinetic energy using gravity
its both man
wave energy and gravity and rider muscular input
sort of like a holly trinity
you guys have been saying nah
its all gravity
its like skating or snowboarding
when obviously
its not
becuase a wave
unlike a half pipe or mountain is moving water
you dont say i gonna go surf some gravity toady
or
hmm the gravitys not very good today
Somebody’s reading comprehension of janklow’s posts is not so very good
and somebody is re-directing his line on the fly as one must
according to the wave of reality
and they are the same person
but in new trim!
Nice cutback, Paul. Gravity’s good today, huh?
huh!
nah man, i just dont have the energy to type out exactly how i see things
or the language/edcuation to communicate it.
this disscusion wasnt about gravity it was about Kevins theory on “upward flow of water on a breaking wave”
which it does,
and how it interfaces with the bottom of a surfboard.
but for some reason you guys cant see it and keep going on about gravity being what makes a surfboard go.
i thought we were discussing how Kevins theory could relate to design
if you dont agree with the thoery,
theres no point being here.
is there ?
whats the problem,
havent you ever had your board sucked up the face in steep barell?
or seen vid of guys getting sucked up and over riding too high in the barrel
or do you think that it is gravity that makes kellyS do 6 ft airs. Is that gravity?
if it is, i want some more, How come kelly gets more than me.
I think ill go back to what i know!
making silly kids toys with my dum labourers hands
leave the maths and science for the cleva folks
let you guys figure it out 
Paul,
That is one of the nicest surfboards I’ve seen.
Gravity and wave motion are the prime movers for surfing. This is the most important thing as far as the flow: The upwave flow isn’t even close to the forward motion of the wave combined with its vertical component, so any of its influence is completely overwhelmed–it’s an incidental feature of the wave itself. The flow could not even happen at all and surfing would still work because of wave motion and gravity. When a gentleman gets thrown over the wave, he’s actually failing to direct himself properly toward gravity to stay ahead of the wave’s swift motion beachward–obvious, when you think about it. Aerial maneuvers successfully executed use these two exact factors and various vectors of momentum in a proper (complicated) ratio. When you get toward the lip, the flow we’ve been talking about is actually a feature of the wave–it’s the differential between the wave pulse’s foward speed and the relatively stationary body of water that was was there a moment before.
The upwave flow is minimal in the first place, and in the final analysis, insignificant, versus gravity’s pull and wave motion. Even at low speed moments, paddling into a wave, recovering from a deep gouge/turning/braking maneuver, the wave motion and gravity give the push that gives plane.
But if you want, you can think of it when you design your surfboards, because the relationship of a rider—who when accumulating the speed that makes a ride possible, is planing downward with gravity—with the water surface, in terms of relative velocity of the two things, he could be riding a stationary wave with a 20 mile per hour flow upwave. This relative appearance is what fools you. The difference is that (for instance) while an upwave flow is moving about 4 miles per hour, while the wave is moving beachward about 16, and the diagonal line of a surfer (almost unconsciously) incorporating gravity into his riding strategy increases his over-water speed even more.
And so, at the end of a wave, gravity and the wave’s overall motion have moved you swiftly beachward, while the upwave wave flow has been a incidental feature that played an insignificant part in your ride and propulsion.
There’s no shame in being wrong about something that insignificant.
Again, that’s one of the nicest wood surfboards I’ve seen. That’s real.
Silly,
A beachward ‘flow’ of 4mph can’t push a surfboard which is travelling beachward at more than 4mph. . .
You say that you don’t have enough energy, language or education to discuss this issue. . . . but most of the discusion is in plain english. . .
Thankfully you are not designing passenger aircraft.
“The plane flies because of the flux” ( aircraft carver no 1)
“We don’t need to know why they fly, just carve the plane and fly it man” (aircraft carver no 2)
Looks like aircraft to me, Paul–I couldn’t fly it though!
More Flow Pictures
As always, analyzing wakes is sketchy business, but until someone pops for a lot of sensors and various other bits of equipment it’s all, at least I have. And as always, the following proves nothing.
In the initial photo, the one with the initial post, I was hoping that someone might comment on the lateral fin gap in the root spray. No one did, in fact no one wrote much of anything. I suspect it was because few cared, or that those who stopped by saw the whole exercise as meaningless. Any way here’s another shot. This is truly impressive, especially if you buy into my hypothesis, actually its truly impressive even if you don’t.
Check out the beachside lateral fin gap, in particular its direction. Maybe he’s riding some bizarre fin arrangement, but maybe he’s not. I will assume he’s on a tri-fin with the usual cant and toe-in.
(Edit: 08/27/06. Corrected misspelling, kant to cant. KC)
My interpretation is that the flow from under his board, just before his fin is headed out to the rail more or less towards the beach. But the fin manages to take this flow and direct it back. My hypothesis would suggest the same is happening on the other side, but its sent into the wave (there is a wee’wake line there to suggest this is what might be happening.) As a beside, it does sort of make you wonder what your fins might be doing sometimes - its all about bottom, or in this case surface presentation to the flow, see the this and prior ‘Dynamics’ threads.) Some fin setups might be doing more that merely helping you go straight.
Perhaps he’s just finished a pump or a drop, but I don’t think so, perhaps he is dropping through a gravitational field but I don’t think so, perhaps like a water skier he is just burning off some kinetic energy with a big turn, but I don’t think so. Here’s what I think; I think this fellow is being propelled by the wave – the flow is hitting his board from a direction close to perpendicular to his motion down-the-line (or what’s left of down-the-line for him) but exactly at what angle relative to his board is difficult to say, he seems to have some some pitch, roll, and yaw going for him, all albeit slight, but my guess, the general directions is up through his but, give or take – basically up, but forward towards the beach.
Kevin
(Edit: 08/26/06. I forgot to include the following thought. If fins could be playing a role in propulsion, then why not more cant and toe-in, -i.e. more of a good thing? I believe it is because at some point it starts to work against whatever benefits you it can achieve by simply producing drag. It goes back to the idea that its one thing to design for propulsion, and another to design for the motion it produces, see prior thread Dynamics - The Trim Equation. KC)
(Edit: 08/27/06. Corrected misspelling, kant to cant. KC)
(Edit. 08/27/06. Pointer adjustment to picture label. KC)
Quote:
perhaps he is dropping through a gravitational field but I don’t think so KC
Well I don’t know where it is possible to surf without being in a gravitational field… .
the lip appears to be falling downwards, which suggests a gravitational field. . .
also the fact that the surfer is attached to the board without straps suggests a gravitational field.
. . and of course without gravity the surfer wouldn’t be pushing down on the water like that either. . . or making a wake,
and without gravity it would be impossible to travel across the wave, but yeah it’s an amazing photo, one suspects a drop in. . . . that’s when I see that view. . during a drop in.
Cheers,
roy
Is there another kinder assessment for that quote besides “hallucinogenic nonsense?”
I begin to think there must be a product the gentleman is trying to sell somewhere, besides the anti-matter on offer here…
A helpful tip: the word is “CANT” not “KANT”
As in “Gilligan, you cant surf without gravity, and you cant surf without wave motion, and you cant seriously be on your 3rd thread about this utter claptrap. And as you say, you cant give evidence for any influence. Cant you stop?”
Please excuse me for correcting you Sir but it isn’t necessarily the case that the correct word is ‘Cant’. . . . . if the board just happens to be powered by dried and ground up Philosphers then ‘Kant’ could be the correct term. . . e.g " More powdered Kant!. . this low gravitational field isn’t providing enough speed "
Ah yes, perhaps what Kevin has discovered is the “transcendental unity of apperception”!
Apologies.
I stand corrected the spelling is cant not kant.
Thanks to those who have pointed this out.
Kevin
(Edit: 08/27/06. Corrections have been made in this thread. KC)
cheers janklow thanks for the compliment
6 pounds with fins grip and wax (apparently too light for some punters)
and strong as an ox
I understand what yor saying btw
with out forgeting that riders effort is a fair percentage of the whole equation
ie. build a board, paddle it out,paddle for the wave. set the rail. compress legs in and unweight out of turns
wave positioning, eysight etc etc
roy
i can draw the pretty pictures and let someone else figure out the maths
im an artist/craftsman
i know some really smart people that cant rebuild a motor or build a house(or change there oil for that matter)
they are simply not good with their hands
im not good with maths
so your reasoning isnt really fair
so in answer to your question
the artist to design it (and hopes it will work)
the smart guy to know the pyhsics ( and have a fair idea if it will work or not)
and the carpenter to build it (usually knows by instinct if it will work or not)
but seriously
i get where your coming from.
that is an interesting picture btw kevin
gives me all sorts of ideas
thanks
this is where i sign out
its been titilating
catchyas
Regarding spelling correction, here is corrected picture.
I also took the opportunity to rephase the comment.
Thanks again,
Kevin
(Edit. 08/27/06. Pointer adjustment to picture label. KC)
Correcting the spelling is a bit superfluous, it’s the theory that needs correcting.
.
I’m curious, when you made this comment did you have the kind of model that Knistle had in mind in his ‘Surfboard Design and Construction’ http://jfmillbiz.home.comcast.net/…onstruction_1977.pdf ? (See oneula post in Dynamics - Water Particle Motion, And The Forces Developed By Moving Liquids)
I’ve read Knistle a few times now and its kind of nice. I wouldn’t claim to know what Knistle was thinking, but perhaps Knistle saw the same propulsive force (that I have been attributing to the impact of water particles on the bottom of the surfboard) but simply decided to resolve it differently, and this lead to his interpretation. (In Knistle’s treatment, the propulsive force appeards to be resultant of both his inertial and buoyant forces.) Where you thinking along similar lines?
Kevin
I haven’t read that book but was simply reflecting upon the fact that your “upward forces” neglected to consider buoyancy, which certainly can be a powerful upward force on a surfboard - whether hydrostatic or hydrodynamic, it’s there and is a component of “lift” if you want to think of it that way.