No it isn’t. . . gliders do it all the time. . . just because the surfboard isn’t moving relative to the vertical frame of reference does not mean that the surfboard isn’t falling due to gravity. . . … … . … .quite clearly gliders and surfboards can fall under the influence of gravity without losing altitude. . . .
As far as your drag comment goes, although all surfboards experience drag it isn’t the case that this drag necessarily limits terminal velocity on a given glide path to a speed less than that obtained in a 2 metre free fall. . . . . a glider free falling 2 metres from a standing start will attain less speed than the terminal velocity of a glider at it’s shallowest possible glide path. . . . although clearly it will take a longer period to reach that terminal velocity. … . . the same applies to surfboards in trim. . … .
I am surprised that you object to this obvious truth, particularly since it supports the idea (which you subscribe to) that gravitational potential energy accounts for most of the force driving the board and rider.
the idea (which you subscribe to) that gravitational potential energy accounts for most of the force
Oh, all right, I’m sorry–it’s just that this crank thread gets me right cranky!
Gravity, not gravitational whatsis you say.
Grade (renewing), waveform push, and gravity–not potential, not opposite or horeezontal flows, just the plane old push of the wave and the grade and the gravitational pull of the bl…I mean, of the honking blue Earth–not something no one ever experienced or perceived because they were all so dull and stupid, but the very thing of the thing, something quite obvious and yet profound, not something faint and wee and slow, but the big mounty swift movie bastard behind yer tail, you great friendly lot of not-insane-or-asinine-at-all-or-cranky-by-any-means good fellows you. All right?
: )
PS: All right about your gliders and their multi-thousand-foot glide traj then–when you talk about gravity and terminal velocity, you ought to define your terms and conditions down to surfing wave scale, otherwise someone might think you’re talking about 100-200mph … of course, you’re surfing at those speeds on those Royboards these days, aint ya–GPS ever come right then Roy?
How’s that tunnel fin work again? Generates vortices does it? Like concentrated spinning spirals of low relative pressure with the control surfaces as their propagation source/suction focus, eh? And they make ye go faster, do thee? So did ye ever get your GPS to read you right, then?
Nnow, what were you boys saying was causing surfing, again? Autofellatular circulars? Oppositionalational flowers?
You’re not getting it. The rotating water particles are not important to surfing the wave. If they didn’t rotate we would still be able to surf. The only reason the water particles rotate is because they are fluid.
Janklow has come up with an excellent analogy with the steel wave to demonstrate how simple it is.
The upward flow of water particles produces negligible propulsion if any. The water particles do not move faster than the lift of something floating in them. This would be similar to standing on the steel wave and letting it pass below you.
Ask yourself, if the water particles did not move in the circular pattern, would you get to the top of the wave any slower?
You’re not getting it. The rotating water particles are not important to surfing the wave. If they didn’t rotate we would still be able to surf.
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If the particles didn't rotate there would be no surf, and the vital lifting power of the wave would not exist without vertical water movement. . . . that vertical water movement just happens to be part of a rotational movement. . . . obviously the horizontal component is not vital for surfboard propulsion. . . . the vertical movement is sufficient to lift the board and impart gravitational potential energy to the board . . . . this being the main source of propulsion, however the horizontal water movement exists and can move the board. </blockquote></div>
The water particles do not move faster than the lift of something floating in them.
Yes, exactly. . . . I have never implied otherwise. . . . .
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The upward flow of water particles produces negligible propulsion if any. The upward flow of water particles produces negligible propulsion if any.
The upwards flow of water particles propels the board vertically, but more importantly, it imparts gravitational potential energy to the board . . … . . I suspect that you think I am subscribing to some mysterious ‘Kevin Casey’ propulsion theory, when in fact I am not. . . . .
The vertical component is the wave pulse–to speak of the particle (that is part of the waveform given entirely by the energy pulse) as the actor is to approach the animal from the wrong end, you see.
There are a lot of sheep in New Zealand, aren’t there?
All right about your gliders and their multi-thousand-foot glide traj then–when you talk about gravity and terminal velocity, you ought to define your terms and conditions down to surfing wave scale, otherwise someone might think you’re talking about 100-200mph …
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I can’t imagine anyone silly enough to think that. . . . but the fact remains that a trimming surfboard is on a glide path and is propelled by gravity. . … . whether gaining or losing altitude . . . . the force propelling a trimming surfboard is mostly gravity. . . . . I was under the impression that you agreed with that idea BTW.
How’s that tunnel fin work again? Generates vortices does it? Like concentrated spinning spirals of low relative pressure with the control surfaces as their propagation source/suction focus, eh? And they make ye go faster, do thee?
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Don't be ridiculous please, of course a tunnel fin doesn't propel the surfboard, it is quite simply a means of reducing overall surfboard drag. . . . which can improve speed. .. . . </blockquote></div>
. … obviously the horizontal component is not vital for surfboard propulsion. . …
… .The upwards flow of water particles propels the board vertically…
Roy, did I ever tell you what we call an unsubstantiated assertion here in Texas? It’s not considered a curse word, either. Just a blank assessment of the facts. Hold that thought–I have to get this call…
to speak of the particle (that is part of the waveform given entirely by the energy pulse) as the actor is to approach the animal from the wrong end, you see.
Hear hear! Winner! Good one, old man! Who said that? Oh…
to speak of the particle (that is part of the waveform given entirely by the energy pulse) as the actor is to approach the animal from the wrong end, you see.
I didn’t imply that the water particles are the source of the energy. . . . which is what you appear to be accusing me of. All I have been saying (at least in relation to vertical flow) is that the wave energy lifts water, and that water lifts the board. . . … .
to speak of the particle (that is part of the waveform given entirely by the energy pulse) as the actor is to approach the animal from the wrong end, you see.
I didn’t imply that the water particles are the source of the energy. . . . which is what you appear to be accusing me of. All I have been saying (at least in relation to vertical flow) is that the wave energy lifts water, and that water lifts the board. . . … .
Ah. Well, then. Waves happen, things float up them, surfers go down them. I think we can wrap this up.
There are still a few matters to sort out. . . like the fact that the wave energy also moves water particles horizontally. . . . . and under what circumstances (if any) that horizontal particle movment can move the board with it.
And then there’s the business of the glide path in trim. . . . if I am interpreting the yelps and yodelling coming from a certain corner correctly there is still some impediment to understanding this basic concept. . . . so when I get back from the beach maybe we can sort it out.
This diagram is pretty much everywhere in the literature, and is in fact easily verfified by observation. Watch surfers waiting for waves, as a wave passes they bob up and down, in fact they make a little circle. Doesn’t meen that water moves with the wave. A circle makes perfect sense. They move inward as they lay in the shoreward downhill side and move outward on the seaward downhill side after the wave passes. Maybe something else is going on as well, but it’s not flow. A wave is not a flow.
Movement, flow, what’s the difference ?. . . . there’s no difference !
Surely you are not attempting to deny the fact that when a wave of energy passes through water it causes that water to rotate in a circle ?
Given that you accept the fact of circular water movement, then it is impossible to deny that there is a beachward horizontal component to that movement
What we have to figure out is what effect that horizontal movement has on a surfboard.
