The dynamics of a breaking wave
sponge
probably write a book on. However, so little is actually
captured on paper. Here are some topics for discussion:
1. Duckdiving a breaking wave. Ever notice that if the lip (of
a medium-sized wave) falls right in front of you, it is still
easy to duckdive unscathed? It's only after a little while that
the turbulence works its way really deep. I believe it's
because the initial impact does not penetrate too deeply. Why?
Surface tension?
2. Turbulence depth. While bodysurfing, I noticed that the
turbulence almost never goes all the way to the bottom. There's
always a little cushion where you can duck under without
problem. Lots of pressure though. Is this always the case?
3. The null spot. Once a wave breaks, there seems to be a null
spot where the energy coming down is neutralized by the energy
bouncing back up. On *rare* occasions, I've been able to punch
through a broken wave with *very* little effort. I can't figure
out when and how to find it, but it is about a full second after
impact. Any theories?
3. Shockwave. The breaking lip many times creates a smaller
wave in the tube. Mike Stewart called it a shockwave, and he is
known for using that mini-wave's energy to help push him out.
I've only got bounced off my board in the tube because of it.
Anybody know how to harness that energy?
4. Foamball. The very inside of a tube is usually this rolling
mass of whitewater, that tries to eat you up. Does anyone know
how to ride it?
5. Spit. Why do waves spit? My guess is that as a tube
collapses, the compressed energy just shoots out the only
available opening.
6. Coming down. When I do an aerial over a closeout section
(which is rare), there are certain spots of the breaking wave
that makes landing so soft and easy. Of course, launching too
far out, makes you go in the flats for a bone-jarring
experience. But launching short could possibly land you right
where the lip is pitching down, giving you a one-way ride to the
bottom. Anybody know exactly where the ideal landing spot is?
This theory would apply to surfers executing a floater with
speed.
7. Punching through. We talk about duckdiving a wave lots, so
I won't go there. However, another useful skill is
the "Hawaiian Pull-Out" while riding the wave. Any points on
when to do it so that you come through clean?
Still got lots more questions in my head. These are things that
I've picked up through the years and I've pretty much never
compared notes with anyone on these things. I welcome the
responses.
sponge
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Foon
questions, most of which I have no knowledge of (I have yet to
finish my Book of Waves) I have some opinions and some
insignificant experience of which he talks:
>1. Duckdiving a breaking wave. Ever notice that if the lip (of
>a medium-sized wave) falls right in front of you, it is still
>easy to duckdive unscathed?
I'm not sure this is true, since if even a medium wave falls
right in front of me, I have either 1) Bailed like a pussy 2)
started diving for the bottom long before it gets to me. So yes,
in a certain respect it is easier because I start sooner.
>because the initial impact does not penetrate too deeply. Why?
>Surface tension?
I have had the unfortunate experience of having an already broken
wave reach down to the bottom where I thought I was safely
hiding, pick me up and rag me. All the tension was me wondering
when it would let up.
>2. Turbulence depth. While bodysurfing, I noticed that the
>turbulence almost never goes all the way to the bottom. There's
>always a little cushion where you can duck under without
>problem. Lots of pressure though. Is this always the case?
No, see previous. Delmarva beach breaks are very good at breaking
deep on shallow sandbars.
>3. The null spot
I have witnessed miracles too, where certain death waves prove
to be tepid tumblers until they get a head of steam and dump more
of their water into the trough.
>
>4. Foamball. The very inside of a tube is usually this rolling
>mass of whitewater, that tries to eat you up. Does anyone know
>how to ride it?
I've seen this phenom from the inside and know for certain if
the foamball catches me, the turbulence or even air in the water
serves to slow me down resulting in a foondunk.
>
>5. Spit. Why do waves spit? My guess is that as a tube
>collapses, the compressed energy just shoots out the only
>available opening.
You sir, are a master of the obvious :)
>
>6. Coming down.
I marvel at people who can pull off floaters in 10 foot faces. I
can't understand what supports their board in the descent. It's
mostly air, right?
>7. Punching through. We talk about duckdiving a wave lots, so
>I won't go there. However, another useful skill is
>the "Hawaiian Pull-Out" while riding the wave. Any points on
>when to do it so that you come through clean?
I owe my survival to this maneuver and it has saved me many
thrashings. It has less to do with the right spot as much as it
has to do with redirecting speed into power to punch through. For
BBers it is much easier to execute. I aim for the middle of the
wall. Too high puts you at risk for getting sucked, too low puts
you at risk for being washed in. The other thing is getting the
right angle into the wave face. Perfectly perpendicular is my
goal even if I have to turn on a dime 180 degrees to do it. Even
as I enter the wave face I begin paddling and kicking to keep my
momentum.
>Still got lots more questions in my head.
Like the corellation of the biggest set coming when you are the
most tired and unable to defend yourself on the paddle out?
Like the mystery of accidentally inhaling a lung full of water
just as you are taking off on your wave of the day?
Like wondering why you feel compelled to take off on the smallest
wave of the day just before the best set of the day comes in?
I'm curious about these too, but my head hurts thinking about
duckdiving one of those bombers you and Bud think are ripples.
-Foon
Doc
"sponge" <spongeN...@iav.com.invalid> wrote in message
news:2d4c10dc...@usw-ex0104-032.remarq.com...
> There are so many dynamics to a breaking wave that you could
> probably write a book on.
In point of fact, I know of a guy who has a website under construction on
precisely that, plus a lot more. Currently, the first section deals with the
terminology and concepts...and I'd have to say that it's at least the
equivalent of a Survey of Physics course at a good college. Though better
done and much clearer.
You cringe, hearing that. Uh huh. Thing is, all the handwaving and such in
the world won't really get the understanding across without the terminology
and concepts inherent in physics and hydrodynamics, any more than I can
adequately describe Impressionism and, let's say, Monet , without pictures
and some history.
>However, so little is actually
> captured on paper. Here are some topics for discussion:
>
> 1. Duckdiving a breaking wave. Ever notice that if the lip (of
> a medium-sized wave) falls right in front of you, it is still
> easy to duckdive unscathed? It's only after a little while that
> the turbulence works its way really deep. I believe it's
> because the initial impact does not penetrate too deeply. Why?
> Surface tension?
In an attempt to prove that I can't adequately describe this without physics
concepts...... and I ask the forgiveness of the real hydrodynamics types who
read this for sloppy terminology and what will appear to be some
hashed-together concepts. Ric, Jose, sdbchguy...HEEEEELP!!!!
Consider that mass of water coming down...the lip. How big an area it
covers. Now, if you were falling off a wave that big (you have pretty close
to the density of water ) and you landed flat or along your whole side, how
far down would you go? There is an energy transfer (the turbulence: it takes
some energy to get all that water swirling around ) and a bit of a shock
wave/surge transmitted, but you're out in front of it. If you can go under
it and use the surge/shockwave to push you a little deeper, there you go.
Surface tension is another thing entirely, I'm afraid. That's more along the
lines of what allows insects (very lightweight insects) to move across the
surface of still water. It's a pretty small scale thing.
>
> 2. Turbulence depth. While bodysurfing, I noticed that the
> turbulence almost never goes all the way to the bottom. There's
> always a little cushion where you can duck under without
> problem. Lots of pressure though. Is this always the case?
Couple of things happening here. The ratio of water depth to wave size has
an effect, I would think. For instance, try jumping off a stepladder into
the deep end of a pool. You don't go all the way to the bottom, instead you
reach a point and start coming back up again. Follow this reasoning with the
thought experiment (don't _do_ it, just follow through the thinking. ) of
jumping off a tall ladder into the shallow end of the pool. You have more
energy and less distance in which to disperse it......okay, less depth to
use it up in..and you whack into the bottom pretty hard. So much in the same
way, except for big waves breaking in comparatively very shallow water, the
turbulence-making energy gets used up before it gets all the way down.
Second....water doesn't compress much...not enough so you'd notice, anyhow.
It transmits pressure and shock waves very well indeed. When a two meter
wave is breaking onto the water's surface, and let us say you are a meter
under the surface, well, for all intents you have a water column three
meters high (three times as tall ) on top of you all of a sudden. Quick
pressure change. Plus, there may be some rebound effects off the bottom...
in any event, you feel a pressure increase.
>
> 3. The null spot. Once a wave breaks, there seems to be a null
> spot where the energy coming down is neutralized by the energy
> bouncing back up. On *rare* occasions, I've been able to punch
> through a broken wave with *very* little effort. I can't figure
> out when and how to find it, but it is about a full second after
> impact. Any theories?
This is coming back up, right? Maybe the wave has (mostly) broken and isn't
throwing much more over: your momentum coming up isn't meeting much coming
down.
>
> 3. Shockwave. The breaking lip many times creates a smaller
> wave in the tube. Mike Stewart called it a shockwave, and he is
> known for using that mini-wave's energy to help push him out.
> I've only got bounced off my board in the tube because of it.
> Anybody know how to harness that energy?
Timing and positioning, similar to landing after air. I'll get to that-
>
> 4. Foamball. The very inside of a tube is usually this rolling
> mass of whitewater, that tries to eat you up. Does anyone know
> how to ride it?
Well, in order to ride a wave, you have to plane on it. If it's not solid
enough to do that, you are gonna sink into it until you reach a point where
the planing surface of your board is enough to support you...if such a
point exists. Sounds kinda like jumping into the washing machine, though,
too much turbulence.
>
> 5. Spit. Why do waves spit? My guess is that as a tube
> collapses, the compressed energy just shoots out the only
> available opening.
Close. For 'energy' substitute 'air' .
>
> 6. Coming down. When I do an aerial over a closeout section
> (which is rare), there are certain spots of the breaking wave
> that makes landing so soft and easy. Of course, launching too
> far out, makes you go in the flats for a bone-jarring
> experience. But launching short could possibly land you right
> where the lip is pitching down, giving you a one-way ride to the
> bottom. Anybody know exactly where the ideal landing spot is?
> This theory would apply to surfers executing a floater with
> speed.
Okay, a digression-
Remember Eddie the Eagle? British ski jumper, go for it kind of guy with
eyesight akin to that of a mole. Which didn't help a whole hell of a lot in
his ski jumping. He'd take off from the ski jump, soar out and then land in
what i'd have to call a hairball. Kerashkaboomwhubbawhubbawhap...and he'd
slide to the bottom of the landing hill.
What was that? 'The landing hill'?? Right.
Here's how a ski jump works. You start out waaay up there, go down fast and
then the ski jump turns and shoots you horizontal...not up, horizontal.
You immediately start to fall (yes, you...no way in hell are you gonna catch
me on one of those things. ) And you continue to fall. But you are also
headed out, away from the hill. Eventually, gravity being kinda constant,
you are falling as fast as you are going outwards and your actual path
through the air is half outwards and half down: you're going about 45
degrees to the horizontal.
But not to the landing hill...that's at about 45 degrees to the horizontal
too. You lightly ease down onto that very angled surface and zoom along
nicely, no sudden stops. If you had landed on a purely horizontal
surface...whap. Crunch.....it gets ugly.
Okay, you have to understand that energy, momenum, force, they not only have
an amount, they have a direction. What happens when you contact a surface
that is not lined up with the direction you're headed in, well, you lose a
lot of energy fast. If you are headed down, your edges want to be headed
down and you want to slide along it. If you land straight down onto the
flat, you get an effect like Wile E. Coyote...with sound effects. If you are
aimed in the direction of the surface you land on, then it's an easy glide,
a smooth transition like a good ski jumper. You slowly change the direction
of motion, not abruptly.
A terminology note...if I had been able to use vectors and some diagrams, I
could have said that whole mess far better and more completely in a medium
length sentence with maybe two diagrams. That was, in my non-humble opinion,
a miserable explanation. And why the forthcoming real explanation of all
this starts with terminology and concepts in considerable depth. Not by me,
thank Huey.....
>
> 7. Punching through. We talk about duckdiving a wave lots, so
> I won't go there. However, another useful skill is
> the "Hawaiian Pull-Out" while riding the wave. Any points on
> when to do it so that you come through clean?
Speed and direction again. If you are going fast enough, pointed in the
right direction, your momentum translates to penetration.
Toss a flat rock just about straight up over a pond. Kersploosh. Straight
in.
Take another identical rock...heh heh...by the time you find two identical
flat rocks I can come up with a good explanation.......
Throw one straight up and the other one paralell with the water's surface.
Kersploosh and ...skip.....skip...skip..skip...skipskip..splish.
The direction was important. The one coming down from way up went straight
in and penetrated with some speed and some depth. the other one just bled
off a little energy on each skip until it just dribbled into the water. No
penetration to speak of.
Now, and it's kinda weird for a New England Yankee to be explaining Hawaiian
Pullouts to a Hawaiian, if your direction is straight into the wave with
some speed...and of course if you are set up to present as little water
resistance as possible...in you go, past the point where you'll be sucked
over backwards. If you are mostly directed parallel to the wave..and that
includes up and down... you don't penetrate, no matter how fast you are
going. And you are very likely to have a chance to investigate that
'foamball' phenomenon at close hand, albeit briefly.
>
> Still got lots more questions in my head. These are things that
> I've picked up through the years and I've pretty much never
> compared notes with anyone on these things. I welcome the
> responses.
>
> sponge
Wayull....now that I have taken a very crude shot at it, I hope somebody
takes this further and better.....
Doc...."Blue water's my daughter, gonna skip like a stone" -Tom Waits.......
Michael Sullivan
>
> There are so many dynamics to a breaking wave that you could
> captured on paper. Here are some topics for discussion:
I've had a couple things on my mind and learned
something new this past winter that helped me.
>
> 1. Duckdiving a breaking wave. Ever notice that if the lip (of
> a medium-sized wave) falls right in front of you, it is still
> easy to duckdive unscathed? It's only after a little while that
> the turbulence works its way really deep. I believe it's
> because the initial impact does not penetrate too deeply. Why?
> Surface tension?
We tend to think of the lip pounding down onto one
single spot, that's what it looks like. But as
the wave is pitching forward, it strikes new water,
(tough to describe). I've noticed this bodysurfing,
and unfortunately a couple times I took this for granted.
Just a couple months back, a good sized set came in,
I had to work hard thru the first one, got to the
impact zone for the second beast, then got lazy. I
did an easy dive and tried to simply streamline thru,
the wave sucked me over the backside. Someone
on the shore would have gotten a great show! Did
I get worked!
>
> 2. Turbulence depth. While bodysurfing, I noticed that the
> turbulence almost never goes all the way to the bottom. There's
> always a little cushion where you can duck under without
> problem. Lots of pressure though. Is this always the case?
no, not always, but yes mostly. I used to have
this habit when stuck inside huge stuff to go right
to the bottom and play flounder, I've been picked off
the bottom and sucked all the way over, again, should
have been a great show! . I figured out just this
winter to keep a long streamline and dolphin thru.
I used to simply scissor kick all the time, but that
seems to create a lot more drag when I'm fighting the
turbulence.
OB in San Fran can be just an impossible swim out at times,
just close big walls of foam rolling in for 50 yards with
no apparent channels. I found I could get out quickly by
dolphining deep under water for 20 yards at a time. The
surface water seems to be constantly moving toward the
beach, even between the broken waves, I reasoned that
the water near the bottom MUST be still or even moving
the other way - again, no channels. The
awful flaw of this strategy is coming up for air right into
a breaking wave - haven't figured this part out yet :^)
that cost me dearly, I coughed for two weeks.
I practiced this in the pool until I got comfortable,
pissed off the lap swimmers, I'd pass them underwater.
(talk about aggro locals). I was never on a swim
team of any kind, so this stuff was tough for me
to learn. I get my kids to coach me.
I know this doesn't apply to board riders, oops.
What's funny was I was all proud of myself as I thought
I made some grand discovery, then at the contest I was
in last month, the bsurfers were dolphining all over
the place like... well, dolphins.
>
> 3. The null spot. Once a wave breaks, there seems to be a null
> spot where the energy coming down is neutralized by the energy
> bouncing back up. On *rare* occasions, I've been able to punch
> through a broken wave with *very* little effort. I can't figure
> out when and how to find it, but it is about a full second after
> impact. Any theories?
I know what you mean. No clue here. I call it
a 'wormhole'. Just dumb luck for me.
Jose B ought to be able to help us, didn't he just get his
PhD in this kind of stuff?
Mike
Mountain Man
>There are so many dynamics to a breaking wave that you could
>probably write a book on.
an ocean of books ---
there are so many waves.
>However, so little is actually
>captured on paper. Here are some topics for discussion:
Good onya sponge.
>1. Duckdiving a breaking wave. Ever notice that if the lip (of
>a medium-sized wave) falls right in front of you, it is still
>easy to duckdive unscathed? It's only after a little while that
>the turbulence works its way really deep. I believe it's
>because the initial impact does not penetrate too deeply. Why?
>Surface tension?
Inertia of the existing water trying to be moved
by the water in the lip is insufficient unless the
lip is big. The further water stacked up behind
the lip adds its weight later.
>2. Turbulence depth. While bodysurfing, I noticed that the
>turbulence almost never goes all the way to the bottom. There's
>always a little cushion where you can duck under without
>problem. Lots of pressure though. Is this always the case?
I have found it to be, unless there is no water
left over the bottom (ie: shallow at low tide). Where
there is sufficient water left (and I'd guess this
would again depend on the size of the incoming breaker)
there has always seemed to be what I called an underflow
running out to sea close to the bottom.
Water cannot be compressed. It can only be moved around.
If water is surging shorewards, other than a rip, it must
also flow out. It flows out next to the bottom - or some
of it does.
>3. The null spot. Once a wave breaks, there seems to be a null
>spot where the energy coming down is neutralized by the energy
>bouncing back up. On *rare* occasions, I've been able to punch
>through a broken wave with *very* little effort. I can't figure
>out when and how to find it, but it is about a full second after
>impact. Any theories?
MTM_Theory (1): The duration of the initial impact is finite,
and the water will try and find its equilibrium. So there must
happen a time when the downward turbulence from the pitching
wave is exhausted, and is compensated by the existent water.
MTM_Theory (2): No matter how solid the wave is, after a finite
period of time it is non-existent. The water has moved back
(like an eternal fountain) into its original position - from
turbulence to the 'calm awaiting the next break'. The change
from turbulence to calm is not like an on/off switch, and it
seems to me that there are complex modes of change, but that
they always involve 'threads of calm'/'pockets of less dynamics'
slowly pervading the breaking wave environment, until they
prevail over the diminsihing pockets of turbulence.
MTM-Theory (3): The physics of turbulence is not known. You
often read about theories of the beginning of the universe,
and of this or that cosmic phenomena, but in the end, the
current academic physics theories do not come to terms with
the turbulence of a breaking wave --- it represents a big hole
in (formalised) human understanding, due to its complexities
and its chaotic nature.
>3. Shockwave. The breaking lip many times creates a smaller
>wave in the tube. Mike Stewart called it a shockwave, and he is
>known for using that mini-wave's energy to help push him out.
>I've only got bounced off my board in the tube because of it.
>Anybody know how to harness that energy?
See the Emerald Planet (Part II). <G>
>4. Foamball. The very inside of a tube is usually this rolling
>mass of whitewater, that tries to eat you up. Does anyone know
>how to ride it?
Instinct?
>5. Spit. Why do waves spit? My guess is that as a tube
>collapses, the compressed energy just shoots out the only
>available opening.
I agree. The water cannot be compressed and has to move.
Ait however can be compressed and when it finally escapes
down its pathway, does so under pressure.
>6. Coming down. When I do an aerial over a closeout section
>(which is rare), there are certain spots of the breaking wave
>that makes landing so soft and easy. Of course, launching too
>far out, makes you go in the flats for a bone-jarring
>experience. But launching short could possibly land you right
>where the lip is pitching down, giving you a one-way ride to the
>bottom. Anybody know exactly where the ideal landing spot is?
>This theory would apply to surfers executing a floater with
>speed.
I guess its like that Rambo movie where he jumps from the
cliff into the trees. What your looking for is anything to
contribute to the breaking and steerage of the 'big fall'.
>7. Punching through. We talk about duckdiving a wave lots, so
>I won't go there. However, another useful skill is
>the "Hawaiian Pull-Out" while riding the wave. Any points on
>when to do it so that you come through clean?
I have not been to Hawaii, but know that your waves are a
different animal to ones that roll through down here. In
the act of pulling out there is a point of no return, after
which you are forced to commit to escaping out in front
of the close out. The only point I can think of would be
to be aware of the varying thicknesses in the wall and/or lip
through which you are trying to 'pull-out', and aim for the
place where things are more in your favor. Also, I guess
there is an art in "grabbing the wave and swinging though it",
that involves converting the down-the-line momentum into a
direction 'for the punch'.
>Still got lots more questions in my head. These are things that
>I've picked up through the years and I've pretty much never
>compared notes with anyone on these things. I welcome the
>responses.
If you were to discover the complete dynamics of a breaking
wave, sponge, then you would receive the Nobel Prize in physics.
Buzzwords change with the generations and Age, but there is
one around today - again in the discipline of physics - called
the collapse of the quantum wave function - where the quantum
world and the real world finally interface (according to the
authors in this field).
The dynamics of a breaking or collapsing wave is at the heart
of one of the oldest unsolved puzzles of the physical sciences,
and has eluded the best scientific minds for hundreds of years.
Apparently the physicist Heisenburg gave up the study of
turbulence (because it was far too difficult) and instead
studied atomic physics, where he became well known.
How can I conlude my contribution?
By saying this:
This problem - the scientific specifications of turbulence -
is long-standing and should be emminently respected. On the
other hand surfers deal with this physical phenomenom every
day, and revel in its play. Perhaps then, the new understanding
of old problems will emerge through the heart and soul of surfing
and through the experience of STOKE.
Keep the stoke brother sponge.
(Who said fire and water dont mix?)
And thanks for the initiation of this thread.
Yours tuly,
Pete Brown
Mountain Man Graphics,
NEWPORT BEACH, OZ.
http://www.magna.com.au/~prfbrown/tubelink.html
Mama Sus
<skipped some of the awesome questions>
>3. The null spot. Once a wave breaks, there seems to be a null
>spot where the energy coming down is neutralized by the energy
>bouncing back up.
Is this spot in the white (foam)? It sounds like this happens
just
'above' the surface and not in a duck dive. Sounds tricky.
>3. Shockwave. The breaking lip many times creates a smaller
>wave in the tube.
Geeee ... I haven't been in a tube yet ... and you have the time
(and presense of mind?) to analyze the interior!
>7. Punching through. We talk about duckdiving a wave lots, so
>I won't go there. However, another useful skill is
>the "Hawaiian Pull-Out" while riding the wave. Any points on
>when to do it so that you come through clean?
I think I've seen this - but only on waves that looked a bit
'spent' -- in other words not in the peak strength. It looked
sort
of like a short cut to going up over the shoulder to get out. The
surfers angled into and through the wall of the wave. Is that the
same move?
>Still got lots more questions in my head.
Fascinating stuff, Neal ... and fascinating answers from people
so
far!
Mama Sus
Timothy B. Maddux
Michael Sullivan <gc....@forsythe.stanford.edu> wrote:
>The surface water seems to be constantly moving toward
Well, not constantly, but certainly more shoreward
than seaward. It's hard to get good data on that
when you're getting worked :)
>I reasoned that the water near the bottom MUST be still
>or even moving the other way - again, no channels.
You reasoned correctly -- that return flow is the "undertow."
--
.-``'. Tim Maddux, Ocean Engineering Lab, UCSB
.` .`~ Santa Barbara Surfing - http://www.me.ucsb.edu/~tbmaddux/
_.-' '._ "The waves, as always, hold the more insidious addiction."
Timothy B. Maddux
Doc <jfm...@capecod.skipthe.canned.meat.net> wrote:
>Thing is, all the handwaving and such in the world won't
>really get the understanding across without the terminology
Mathematics is just another language that can
elegantly and concisely express the way the
world works.
>Surface tension is ... a pretty small scale thing.
Important for the little ripples ~1 cm long.
Good if you want to study the warbles on the
lip up close as it throws at your head.
[ big discussion of landing floaters trimmed ]
Ok, Doc, but where do I land again? :)
My floaters usually err on the side of hanging
up there too long or too far out the back, and
I wind up sinking into the whitewater. I
guesss it's better than breaking my ankles
while trying to draw some of Doc's vectors
on the salt dried on the back of my hand.
Timothy B. Maddux
mention is the differences from break to break or
from breaker to breaker, depending on shape and
current. Provided we're not talking about nightmare
waves like Pipe or Teahupoo (sp?), I've noted that
hollow reef waves often hit hard but release quickly,
while mushier points will grind and grind and grind
and not let go.
In article <2d4c10dc...@usw-ex0104-032.remarq.com>,
sponge <spongeN...@iav.com.invalid> wrote:
>1. Duckdiving a breaking wave. Ever notice that if the lip (of
>a medium-sized wave) falls right in front of you, it is still
>easy to duckdive unscathed? It's only after a little while that
>the turbulence works its way really deep. I believe it's
>because the initial impact does not penetrate too deeply. Why?
>Surface tension?
You're on the right track with the initial impact, a lot
of which rebounds. Also, the lip is usually thickening
as it continues to heave over, so if you can get under
that first bit you'll be fine. I have also come away
surprisingly unscathed from waves that break right in
front of me.
>2. Turbulence depth. While bodysurfing, I noticed that the
>turbulence almost never goes all the way to the bottom. Is
>this always the case?
I don't think so. Sand transport under waves is usually
a maximum right around where the waves first break, and
again onshore in the swash/backwash. Certainly any time
you see one of those big boils of sediment after a wave
passes, the turbulence has reached the bottom.
It's all relative -- I don't mean the whole lip has plunged down
intact to impact the bottom -- so perhaps it's not something
we can perceive easily when we're trying to paddle and
duckdive. It's certainly been measured with instrumentation
and modellers are just starting to get a grip on it. In
fact, I've got some Tecplot animations from our lab of
breakers that show some of my coworkers efforts to model
this stuff. I'll see about posting some of them as movies.
>3. The null spot. Once a wave breaks, there seems to be a null
>spot where the energy coming down is neutralized by the energy
>bouncing back up... Any theories?
Entrained air coming back up? Anyone else notice how
big waves, with all the air they put into the water,
make it much harder to surface or even stay afloat even
after the wave has gone by?
>3. Shockwave. The breaking lip many times creates a smaller
>wave in the tube.
I'm usually too freaked when I'm in the barrel
to notice something like that :)
>4. Foamball... Does anyone know how to ride it?
I don't. Tom Curren kinda bunny-hops the foamball on a
little fish-type board in Indo, it's in the "Searching for
Tommy Curren" video and was originally shown in "Beyond the
Boundaries" (Rip Curl).
>5. Spit. Why do waves spit?
That's the lighter air escaping and carrying spray as
it goes. If it doesn't escape that way, like in a
closeout, it'll blow out the back of the wave.
>6. Coming down... Anybody know exactly where the ideal
>landing spot is? This theory would apply to surfers executing
>a floater with speed.
I usually try to come down after the lip has first hit
but before the shape of the wave breaks up into whitewater.
>7. Punching through... another useful skill is
>the "Hawaiian Pull-Out" while riding the wave.
>Any points on when to do it so that you come through
>clean?
Would love to get more pointers on this as well.
I often make it through but not with my board.
good thread,
--
.-``'. Tim Maddux, Ocean Engineering Lab, UCSB
.` .`~ http://www.me.ucsb.edu/~tbmaddux/
_.-' '._ "From the essence of pure stoke springs all creation."
Btw72
>There are so many dynamics to a breaking wave that you could
>probably write a book on. However, so little is actually
>captured on paper. Here are some topics for discussion:
There is a grad school class on ocean waves at UF. I won't be taking it.
>4. Foamball. The very inside of a tube is usually this rolling
>mass of whitewater, that tries to eat you up. Does anyone know
>how to ride it?
The mixture of air and water must slow a rider down compared to water, so I'd
say unless the tube is opening up, it's going to drag the rider back into it.
Mike Stewart would know how if anyone would.
>7. Punching through. We talk about duckdiving a wave lots, so
>I won't go there. However, another useful skill is
>the "Hawaiian Pull-Out" while riding the wave. Any points on
>when to do it so that you come through clean?
My bodyboard skills are rusty, but the process is like a duckdive with speed,
but approached from an oblique angle. Streamline to the board to penetrate and
start kicking back out as soon as you can.
BTWeaver
bt...@aol.com
Jason S
<spongeN...@iav.com.invalid> wrote:
I bodysurf with goggles on, so i've had 1000s of hours looking at what
goes on underwater with waves
>2. Turbulence depth. While bodysurfing, I noticed that the
>turbulence almost never goes all the way to the bottom. There's
>always a little cushion where you can duck under without
>problem. Lots of pressure though. Is this always the case?
>
No...
If you have a big wave breaking on a shallow area (relative to the
size of the wave) there is literally nowhere to go.
This is especially true of waves breaking on shallow reefs
Kinda feels like a giant grabs the back of your wetsuit and chucks you
in front of the wave when you get caught out in these situations
Waves break when the ratio of wave size to floor depth is 3:4
If you have a reef or very shallow sand area that dramatically breaks
this ratio, you get this problem.
Eg: a 8 foot wave approaching a reef that goes from 12 foot deep to 3
foot deep in a length of only about 15 feet.
>5. Spit. Why do waves spit? My guess is that as a tube
>collapses, the compressed energy just shoots out the only
>available opening.
>
I'm pretty sure most of this is the air that is trapped in the tube..
You will notice that waves that dont tube dont spit, even if they are
big with plenty of energy
Haavard N. Jakobsen
"Foon" <wfoverN...@nist.gov.invalid> wrote in message
news:0e127eca...@usw-ex0105-034.remarq.com...
> Neal takes a big bite of topicality and chews on a few
> >Still got lots more questions in my head.
>
> Like the corellation of the biggest set coming when you are the
> most tired and unable to defend yourself on the paddle out?
>
Why a set always last as long as you paddle out
and you have to wait a loooooong time for the next one?
> Like wondering why you feel compelled to take off on the smallest
> wave of the day just before the best set of the day comes in?
>
yeah!
-H
Haavard N. Jakobsen
the Neal(and me...)
-H
Gleshna
>1. Duckdiving a breaking wave. Ever notice that if the lip (of
>a medium-sized wave) falls right in front of you, it is still
>easy to duckdive unscathed?
Yes, even for turtling a longboard I can feel a very big difference. I know
that if I can get close to the breaking wave, I am much better of than letting
the energy bounce off the bottom. That is the worse. When the wave breaks
about ten yards in front of me.
I was also told that winter waves in southern California are different than
summer waves. I found this to be quite true. Winter waves tend to break
harder and much deeper.
>2. Turbulence depth. While bodysurfing, I noticed that the
>turbulence almost never goes all the way to the bottom. There's
>always a little cushion where you can duck under without
>problem. Lots of pressure though. Is this always the case?
See summer, winter wave note above. I think that in part summer waves in
southern California are carthwheeling in from the south. They are very long,
stretched out, so I think this dissipates the energy per square inch.
>
>7. Punching through. We talk about duckdiving a wave lots, so
>I won't go there. However, another useful skill is
>the "Hawaiian Pull-Out" while riding the wave. Any points on
>when to do it so that you come through clean?
>
We did these around 1960 at Ocean Beach, San Diego. I consider them a hang
five lead up skill of sorts. Even on small waves you can walk to the nose,
push down and pop the tail. I find them very convenient in tiny surf. I have
never done them on waves over say three feet, except when grabbing a rail going
backside. For me the big thing is speed, getting the board perpendicular to
the wave and timing for the moment of the wave just curling over.
RichyBob
Peter Krivcov
> Like the corellation of the biggest set coming when you are the
> most tired and unable to defend yourself on the paddle out?
>
Oh, definately me personal fave. All this staring at the ocean and trying to
time your paddle out just right. Then the biggest set comes at the worst time.
I don't think it should be possible to be too tired to paddle and stroke for
your life in the face of a big set wave. But I've been there where my useless
noodle arms were not up to the task, and all that's left to do is to try and
take the deepest breadth possible! I guess I should spend some more time at the
gym........unless doughnuts really do seem to help??
Later.
Pete.
Peter Krivcov
Mama Sus wrote:
>
> >3. Shockwave. The breaking lip many times creates a smaller
> >wave in the tube.
>
> Geeee ... I haven't been in a tube yet ... and you have the time
> (and presense of mind?) to analyze the interior!
>
I'm with you! When I finally get to check it out first hand I don't think I'll
notice to many details................. Maybe I'll bring a camera!
Pete.
Grey Wolf
posted the following satanic message in <391061B5...@princeton.edu>
The other really bad time for a big set is when you're peeing. No amount
of time in the gym can help you simultaneously pee and paddle.
--
Grey "can chew gum and fart at the same time" Wolf
Keep the Earth clean.... it isn't Uranus
sponge
Should've broken it up. Anyway, will respond to some of them.
Foon wrote lots of funny stuff: <snip>
>>7. Punching through. We talk about duckdiving a wave lots, so
>>I won't go there. However, another useful skill is
>>the "Hawaiian Pull-Out" while riding the wave. Any points on
>>when to do it so that you come through clean?
>
> I owe my survival to this maneuver and it has saved me many
>thrashings. It has less to do with the right spot as much as it
>has to do with redirecting speed into power to punch through.
For
>BBers it is much easier to execute. I aim for the middle of the
>wall. Too high puts you at risk for getting sucked, too low puts
>you at risk for being washed in. The other thing is getting the
>right angle into the wave face. Perfectly perpendicular is my
>goal even if I have to turn on a dime 180 degrees to do it. Even
>as I enter the wave face I begin paddling and kicking to keep my
>momentum.
180 degrees? That means you were going straight towards shore.
<grin> Just kidding!
>>Still got lots more questions in my head.
>
>Like the corellation of the biggest set coming when you are the
>most tired and unable to defend yourself on the paddle out?
>
>Like the mystery of accidentally inhaling a lung full of water
>just as you are taking off on your wave of the day?
>
>Like wondering why you feel compelled to take off on the
smallest
>wave of the day just before the best set of the day comes in?
Just corollaries of Murphy's Law. I hear ya, Foonboy. Been
there, done that!
sponge
sponge
.. 1. Duckdiving a falling lip
>>>Consider that mass of water coming down...the lip. How big an
area it covers. Now, if you were falling off a wave that big
(you have pretty close to the density of water ) and you landed
flat or along your whole side, how far down would you go? There
is an energy transfer (the turbulence: it takes some energy to
get all that water swirling around ) and a bit of a shock
wave/surge transmitted, but you're out in front of it. If you
can go under it and use the surge/shockwave to push you a little
deeper, there you go.
When I wrote this question, I was thinking about how a pulsating
laser is more effective at penetrating an object than a constant
beam. I believe that initial impact creates a plasma of sorts
and that, along with reflected photons would cause destructive
interference and slow the penetration.
Similarly, when a lip impacts the water, lots of water is
bounced back. This impedes the rest of the falling lip,
allowing more time to skirt under before the turbulence gets
deeper.
>>>Surface tension is another thing entirely, I'm afraid. That's
more along the lines of what allows insects (very lightweight
insects) to move across the surface of still water. It's a
pretty small scale thing.
I just threw that in for fodder. Wasn't really thinking. Makes
sense, though, what you said.
<snipped turbulence depth>
..3. The null spot.
>>>This is coming back up, right? Maybe the wave has (mostly)
broken and isn't throwing much more over: your momentum coming
up isn't meeting much coming down.
Mike Stewart once said that he sat on his bodyboard as an
oncoming wave beared down (closeout many feet in front of him),
and he punched through unscathed. There seems to be a moment
where the downward force is nullified by the upward force,
allowing someone to pop through.
I've gotten lucky a few times, but could not even imagine
exactly when I could do it.
<snipped Shockwave>
..4. Foamball.
>>>Well, in order to ride a wave, you have to plane on it. If
it's not solid enough to do that, you are gonna sink into it
until you reach a point where the planing surface of your board
is enough to support you...if such a point exists. Sounds kinda
like jumping into the washing machine, though, too much
turbulence.
Hah! That's where bodyboarders may have an advantage. Since we
don't have to hold any fins to maintain an edge (the whole rail
and your body becomes an edge), riding the foamball becomes a
possibility. Stability is managed by just holding on for dear
life!
<snipped Spit>
<snipped Coming down.>
Understand your ski analogy. I was looking more for answers
like where to land.
<snipped Punching through>
Again, fully understand the rock throwing concept. However, was
looking more for the intricacies--when to do it, where on the
wave, variables involved, etc.
Thanks Doc! Good stuff. Would like to continue these kinds of
technical dialog. Tired of reading about druggies, etc.
sponge
Thanks Peter! So much good info and analysis. However, the
item that really got me going was your response to the null spot:
Cosmic! So awesome how our physical act of waveriding cannot be
defined by science, taking on a philosophical and/or even
supernatural and divine nature.
The below words were so eloquent, I had to leave it in case
anyone else missed reading them.
Aloha Pete!
sponge
<The Mountain Man's words on the dynamics of a breaking wave>
* Sent from RemarQ http://www.remarq.com The Internet's Discussion Network *
sponge
> sponge <spongeN...@iav.com.invalid> wrote:
<snip>
>>3. Shockwave. The breaking lip many times creates a smaller
>>wave in the tube.
>
>Geeee ... I haven't been in a tube yet ... and you have the time
>(and presense of mind?) to analyze the interior!
Oh nonono! I read about this shockwave thing before I ever saw
it. At that time, I was unwittingly affected by it. During a
closeout tube, there's this moment where you hit a speed bump.
Many times, that is the mini-wave that is created from the lip
impact.
I still haven't seen it really--too busy trying to get out of
the tube that I tried so hard to get into in the first place.
<gasp!>
But my friends know of it. One buddy, Joel Leo, said that on
one of his big Waimea Shorebreak barrels, the shockwave was over
two feet high. It just pitched him in the air, mid-tube.
Here's Joel on one of them beasts:
http://www.hits.net/~jleo/images/calendar.jpg
sponge (still learning--that's why I'm asking)
sponge
well... I've taken my share of studies in static, dynamic and
quantum physics courses. These inquiries were more to stimulate
discussion rather than try and explain my theories.
sponge (but I slept a lot in my Chemistry courses!)
Doc
"sponge" <spongeN...@iav.com.invalid> wrote in message
> "Haavard N. Jakobsen" <jako...@protective.no> wrote:
> >I kind of get the feeling Doc paid way more attention in
> physics class
> >the Neal(and me...)
>
> well... I've taken my share of studies in static, dynamic and
> quantum physics courses. These inquiries were more to stimulate
> discussion rather than try and explain my theories.
>
> sponge (but I slept a lot in my Chemistry courses!)
Doc taught undergraduate physics and chemistry as a lab TA. I think of it as
penance for a very few of my other sins.......
Doc
"sponge" <spongeN...@iav.com.invalid> wrote in message
> Doc wrote about:
> .. 1. Duckdiving a falling lip
> area it covers. Now, if you were falling off a wave that big
> (you have pretty close to the density of water ) and you landed
> flat or along your whole side, how far down would you go? There
> is an energy transfer (the turbulence: it takes some energy to
> get all that water swirling around ) and a bit of a shock
> wave/surge transmitted, but you're out in front of it. If you
> can go under it and use the surge/shockwave to push you a little
> deeper, there you go.
>
> laser is more effective at penetrating an object than a constant
> beam. I believe that initial impact creates a plasma of sorts
> and that, along with reflected photons would cause destructive
> interference and slow the penetration.
>
> Similarly, when a lip impacts the water, lots of water is
> bounced back. This impedes the rest of the falling lip,
> allowing more time to skirt under before the turbulence gets
> deeper.
I see where you're going with this, but I fear the analogy doesn't hold that
well. The thing is, a laser is a focussed light beam, and while photons are
indeed particles (sort of ), they are not particles that really map onto the
behavior of particles like water molecules falling.
Let's use an analogy to a laser beam: a straight tip on a fire hose,
shooting out what looks like a straight sided column of water out at high
speed. The plasma created by the initial laser hit acts like, oh, a whole
series of fine meshes that chop up the stream so that it is no longer
focussed (by the way, did you know that one form of industrial cutting tool
is a very hig pressure water stream with small grit particles in it?
Interesting stuff...if you're me ) and it doesn't hit with all the energy in
one small spot . Destructive interference indeed.
Pete Brown mentioned something that I didn't think of at all..and it also
applies to that 'shock wave' inside the tube. The water coming down is
definitely not hitting one spot all the time: the spot it's hitting is a
moving point, moving as fast towards shore as the wave is. That in turn
would create a pressure surge headed back out, towards the wave itself. Both
the shock wave and the surge that pushes you downwards and out towards the
back of the wave. Thanks, Pete.
>
> >>>Surface tension is another thing entirely, I'm afraid. That's
> more along the lines of what allows insects (very lightweight
> insects) to move across the surface of still water. It's a
> pretty small scale thing.
>
> I just threw that in for fodder. Wasn't really thinking. Makes
> sense, though, what you said.
Jeez... I must have been having a good day.
>
> <snipped turbulence depth>
>
> ..3. The null spot.
>
> >>>This is coming back up, right? Maybe the wave has (mostly)
> broken and isn't throwing much more over: your momentum coming
> up isn't meeting much coming down.
>
> Mike Stewart once said that he sat on his bodyboard as an
> oncoming wave beared down (closeout many feet in front of him),
> and he punched through unscathed. There seems to be a moment
> where the downward force is nullified by the upward force,
> allowing someone to pop through.
Uhm, yeah. I think, though it would take some modelling and a better mental
picture than I have of the situation right now, but the outward surge I
mentioned above has a relationship to the speed of the wave towards shore
and the speed across the wave that it is breaking. Probably has a geometric
relationship to the shape of the bottom...hmmmm..... dammit, I was gonna
take a nap before supper, but no way in hell I am gonna do that now, this
has got me interested.
Now, as that surge and such is headed out and up the wave, there must
necessarily be another one headed inwards, toward shore. Hmmmm.... this is
very interesting, and the idea that something resists that wave, a sort of
rebound effect, or possibly an effect kinda like you see with backwash.
Maybe even....... (dammit, again, I am gonna be sketching this all evening )
>
> I've gotten lucky a few times, but could not even imagine
> exactly when I could do it.
>
> <snipped Shockwave>
>
> ..4. Foamball.
>
> >>>Well, in order to ride a wave, you have to plane on it. If
> it's not solid enough to do that, you are gonna sink into it
> until you reach a point where the planing surface of your board
> is enough to support you...if such a point exists. Sounds kinda
> like jumping into the washing machine, though, too much
> turbulence.
>
> Hah! That's where bodyboarders may have an advantage. Since we
> don't have to hold any fins to maintain an edge (the whole rail
> and your body becomes an edge), riding the foamball becomes a
> possibility. Stability is managed by just holding on for dear
> life!
Well, it's not so much stability as it is something analogous to buoyancy
or, if you like, skiing in deep powder. You have to sink in until you reach
a depth where the stuff you are planing on is solid enough _to_ plane on.
The problem I see is that that point might be where it is so turbulent that
an edge would be taken every which way and then, well, you and the foamball
are momentarily as one, shall we say.
If Pete doesn't mind.....
"MTM-Theory (3): The physics of turbulence is not known. You
often read about theories of the beginning of the universe,
and of this or that cosmic phenomena, but in the end, the
current academic physics theories do not come to terms with
the turbulence of a breaking wave --- it represents a big hole
in (formalised) human understanding, due to its complexities
and its chaotic nature."
And:
"If you were to discover the complete dynamics of a breaking
wave, sponge, then you would receive the Nobel Prize in physics.
Buzzwords change with the generations and Age, but there is
one around today - again in the discipline of physics - called
the collapse of the quantum wave function - where the quantum
world and the real world finally interface (according to the
authors in this field).
The dynamics of a breaking or collapsing wave is at the heart
of one of the oldest unsolved puzzles of the physical sciences,
and has eluded the best scientific minds for hundreds of years.
Apparently the physicist Heisenburg gave up the study of
turbulence (because it was far too difficult) and instead
studied atomic physics, where he became well known."
Pete puts it much better than I do.
Turbulence is horribly complex, a modelling and computing and theoretical
problem on the order of the problem of long-term weather prediction. As an
estimate of what it's gonna take to to really understand it, perhaps a mind
as capable and wide-ranging as Richard Feynman's or Stephen Hawking's
combined with a whole new toolbox of mathematical methods and approaches
_and_ computing power along the lines of , oh, maybe every supercomputer
existing today.
Then again, it is one of the big questions in physics so it's likely that
the next Feynman or Hawking might take a shot at it, the mathematics are a
hot topic _in_ mathematics today and computing power is getting cheap and
accessible. We might see it happen. The other applications of understanding
turbulence are...well, everywhere.
>
> <snipped Spit>
>
> <snipped Coming down.>
> Understand your ski analogy. I was looking more for answers
> like where to land.
Uhm...it's not so much a where as a how- for instance:
Back around '74, me and my old green kneeboard were playing with 'air'.
When a section was closing out, I'd try to hit it and the lip in such a
manner that I'd be tossed out in front of the wave, nose first, on a path
parallel to the direction my board was pointed in and pretty horizontal so
I'd hit going pretty close to parallel with the water. Like the skipping
stone analogy for punching through a wave, as I was going pretty much
parallel to the water I didn't go straight in....when it worked, that
is...... but stayed on the surface.
In a similar way, if you are going up (then down) and towards the shore, you
want to land on the face of the wave, not out on the flat, so that your
direction and your edges are pretty close to parallel with the surface. If
you land at some place that isn't at least close to parallel to the
direction you're heading, you go straight in like a rock coming straight
down onto flat water.
>
> <snipped Punching through>
> Again, fully understand the rock throwing concept. However, was
> looking more for the intricacies--when to do it, where on the
> wave, variables involved, etc.
Okay, lets go back to '74 again. The old green G&S kneeboard. Having hit out
in front of the wave (and assuming I didn't eat it ) , I'd crank a turn and
head straight into that pullout, straight into the face of the wave.
Whoomph, lots of speed into a perpendicular surface. Penetrating like a lawn
dart.
Now, when do I go straight through instead of another way? When it's steep
and starting to come over and I can't get over the top or out the shoulder
and I have a lot of speed going for me. Then, I go to a hard turn and a
weight forward trim so that the nose goes straight in and the direction I'm
headed is as close to straight back out as I can make it. It doesn't work on
moosh waves and it works better the less floaty the board is. With an old
style minimum floatation paipo (without a whole lot of rocker) it's easy.
Crank it up on edge and go through while banking a turn. I suspect that's
what's happening with a larger board too- the front of the board is acting
as a diving plane in a way, digging into the wave and redirecting, taking
the tail and the fin out of the equation as it were.
>
> Thanks Doc! Good stuff. Would like to continue these kinds of
> technical dialog. Tired of reading about druggies, etc.
Well, everybody needs a hobby......
Doc..... now, as to the _other_ stuff I was doing during the '70s........
Bud
sponge wrote:
> But launching short could possibly land you right
> where the lip is pitching down, giving you a one-way ride to the
> bottom. Anybody know exactly where the ideal landing spot is?
> This theory would apply to surfers executing a floater with
> speed.
My .02-
Can't say much about launching, but . . .a loooong, "section-overcoming" floater
on an overhead wave is something I wish I could accomplish more often. For that,
I would say down the line speed is the key. Afa the ideal spot to land a
floater, I think the biggest factor is how big and/or hollow the wave is. Like
you said, coming down with the lip can be a board breaking situation. I'm sure
we've all seen pics or vid of guys who ride past sections on the back of good
sized waves for incredible distance and then drop back in within a thick
barreling lip! Pretty intense.
Bud
-----------
While writing this reply, I got carried away writing about my limited experience
with floaters and it may not be in line with the thread. Stop here if you're not
interested
-----------
I used to think - why do a floater when you could hit the lip? Eventually I
realized (i.e. seeing others with great talent) that it could be good way to
quickly & effectively get past a breaking section without losing much speed. I
think most would agree - on a fast breaking wave, it can be very difficult to
make it back onto the face once you're stuck in the whitewater.
Of course floaters aren't always done on the back of a breaking lip, but is
often done to fly over a section of whitewater too. However, when I think of a
floater I always envision a surfer on a high line at top speed across the wall
of a fast breaking wave. A portion wall ahead has already started to break;
Instead of trying for a long bottom turn around it, you lift the nose over the
lip, using forward momentum to ride onto the back of, and across the falling
section. Your entry speed is the biggest factor to how far you can go, since
you're now traveling "against the grain" of the falling lip. You have to make a
conscious effort to stay over your board and on the back of the wave, somewhere
between kicking out and continuing toward your point of re-entry. Often, as you
lose speed, the tail starts to get pulled down. It feels strange to be riding on
the back of the breaking wave and not kicking out. Initially, I tended to just
go with it, eventually losing forward momentum and then trying to compensate as
I was going down hard. Not a good situation- the board tends to flip over as you
fall with the lip! That was one of the hurdles for me to overcome - giving up
some distance & learning that you have turn back into the wave *before* losing
too much speed (looks smoother too).
How/where you land becomes less of an issue the smaller the wave (shorter drop).
Landing from a section on a bigger and/or hollower wave will require much more
practice, finesse, and likely some hard falls. Down the line speed becomes much
more critical the bigger the wave, especially if your intent is to bypass a
section, versus hitting the lip and floating back down whitewater back down.
I don't get super long ones very often, but it's a great rush to pull one off.
When you're riding high & fast. . . perhaps there's no time to bottom turn and
hit the lip. . . even a quick floater over a short section can be an effective
and satisfying maneuver.
Good surfing to you,
Bud
MICHAEL HUGHES
Maybe thinking too hard
flek
>From: "Doc" jfm...@capecod.skipthe.canned.meat.net
>Date: 5/3/00 6:11 PM Central Daylight Time
>Message-id: <Mq2Q4.3297$Q7.21...@news-east.usenetserver.com>
ugh, i like cheese.
C.O.D.F.I.S.H. GP2K, a write-in for most lapdances while mixing champagne,
grain alcohol and like, other stuff.
Southoz
"Mountain Man" <prfbrown...@magna.com.au.invalid>
>
> >4. Foamball. The very inside of a tube is usually this rolling
> >mass of whitewater, that tries to eat you up. Does anyone know
> >how to ride it?
>
> Instinct?
...or, lower your center of gravity and hold on tight, grow long talon-like
toenails that bite into your deck and howl like a werewolf during a
full-moon.
> >7. Punching through. We talk about duckdiving a wave lots, so
> >I won't go there. However, another useful skill is
> >the "Hawaiian Pull-Out" while riding the wave. Any points on
> >when to do it so that you come through clean?
>
> I have not been to Hawaii, but know that your waves are a
> different animal to ones that roll through down here.......
I reckon anytime when you see dry reef ahead of you while locked in the
barrel would be a good time to try one.
> This problem - the scientific specifications of turbulence -
> is long-standing and should be emminently respected. On the
> other hand surfers deal with this physical phenomenom every
> day, and revel in its play. Perhaps then, the new understanding
> of old problems will emerge through the heart and soul of surfing
> and through the experience of STOKE.
Left the above, cuz it sounded too good to snip.
Southoz, (still intending to write up a Bell's trip report...)
sdbchguy
>
> ...<much snipped--some of which I agree with, some of
which I don't>...
>
> ...Buzzwords change with the generations and Age, but there is
> one around today - again in the discipline of physics - called
> the collapse of the quantum wave function - where the quantum
> world and the real world finally interface (according to the
> authors in this field).
>
> The dynamics of a breaking or collapsing wave is at the heart
> of one of the oldest unsolved puzzles of the physical
> sciences, and has eluded the best scientific minds for
> hundreds of years.
Let's not confuse the "collapse" of the quantum mechanical wave
field (or the wave equations describing that field) with the
actual collapse of a wave within that field.
SDbchguy
Haavard N. Jakobsen
"sponge" <spongeN...@iav.com.invalid> wrote:
> well... I've taken my share of studies in static, dynamic and
> quantum physics courses. These inquiries were more to stimulate
> discussion rather than try and explain my theories.
>
> sponge (but I slept a lot in my Chemistry courses!)
Chemistry suck, atleast the lecturer I had. That goes for the
one I had in physics too.
Standard phrase on my jobinterviews:
"I see you spent 4 years before you got that exam
in physics. Would you care to explain, mr. H?"
I've kind of played with the idea of visual simulation of a breaking
wave with a computer as a particle-spring-system, but I guess I would
need all the computers in the world to do that. Maybe on a smaller scale,
like in glass of water? or a drop of water....
-H
Doc
"Haavard N. Jakobsen" <jako...@protective.no> wrote in message
news:mZdQ4.3453$kF4....@news1.online.no...
While it can be done ( I believe they rented Cray time for modelling some of
the America's Cup designs and waterflow around them) , it is kinda fierce.
A whole lot of 'packets' of water were individually modelled as was their
motion. A lesser number of 'packets' and a shorter time span might be more
approachable.
Still, I suspect this might be a use for that older computer everybody seems
to have : set up the program, start it and then ignore it for a few days
while it laboriously grinds through the calculations.
Gleshna
>
>>>>Well, in order to ride a wave, you have to plane on it. If
>it's not solid enough to do that, you are gonna sink into it
>until you reach a point where the planing surface of your board
>is enough to support you...if such a point exists. Sounds kinda
>like jumping into the washing machine, though, too much
>turbulence.
At Tamarack, we often had a very fast left that would close out eventually into
a bigger right that had a little reform right if you cut back. I think we
learned what is now called a rollercoaster from a surf film. It worked very
well, and I still find it handy today. It is sorta like free falling but
slower. You do gain momentum that can be used for a bottom turn. The trick
for me is to merely keep the board level during the slow fall.
RichyBob
Haavard N. Jakobsen
"Doc" <jfm...@capecod.skipthe.canned.meat.net> wrote :
> >
> > I've kind of played with the idea of visual simulation of a breaking
> > wave with a computer as a particle-spring-system, but I guess I would
> > need all the computers in the world to do that. Maybe on a smaller
scale,
> > like in glass of water? or a drop of water....
> >
> > -H
>
> While it can be done ( I believe they rented Cray time for modelling some
of
> the America's Cup designs and waterflow around them) , it is kinda
fierce.
> A whole lot of 'packets' of water were individually modelled as was their
> motion. A lesser number of 'packets' and a shorter time span might be more
> approachable.
>
I think the simplified solutions might be enough to gain some extra
knowledge
when simulating waterflow around a hull. For the dynamics of breaking wave,
and to visualize it, I think the number of 'packets' would have to increase,
thus
making it impossible to make it on a personal computer(or 10.)
My first idea was to fill a box half full of balls of a certain
size(variable), then
make an impulse in the box. Make a bottom contour like a reef, make the
balls
infinitly small(thus increasing the number towards infinity) and see what
happens.
Would take forever, even on a small scale.
I can imagine a few other soulutions that would be interesting though,
by using few packets and using different rendering techniques you could
get a visual wave with a lip. Same goes for a "cloth-like" simulation with
a pulse moving through the cloth. Add the forces done on the pulse from
a bottom contour and see what happens.
If I only had nothing better to do....
-H
sdbchguy
>
> sponge <spongeN...@iav.com.invalid> wrote:
>>
>> 2. Turbulence depth. While bodysurfing, I noticed that the
>> this always the case?
>
> I don't think so...<snipped>...It's all relative -- I don't
> mean the whole lip has plunged down intact to impact the
> bottom -- so perhaps it's not something we can perceive easily
My rule of thumb when duck-diving a wave that's broken just
outside me (and which also relates to the depth of penetration
of the energy associated with the lip (now a plunging jet):
If the curtain of entrained air bubbles in the penetrating jet
of water ends at or above my depth, the forces on my board (and
me) are not going to be too severe; if they penetrate deeper
than my depth, there's probably going to be a brief period where
I have to hang onto my board pretty hard; if they go a lot
deeper, (and depending on the size of the wave) it might be
prudent to not put a lot of effort into hanging onto my board.
Michael Sullivan
>
> In article <390ED7...@forsythe.stanford.edu>,
> Michael Sullivan <gc....@forsythe.stanford.edu> wrote:
> >The surface water seems to be constantly moving toward
> >the beach, even between the broken waves...
>
> Well, not constantly, but certainly more shoreward
> than seaward. It's hard to get good data on that
> when you're getting worked :)
>
> >I reasoned that the water near the bottom MUST be still
> >or even moving the other way - again, no channels.
>
> You reasoned correctly -- that return flow is the "undertow."
Tim, is that the honest to goodness real-live
term for that flow? When beach rooks talk to
each other about watching out for the undertow,
they are talking about the beach washback that
can knock them off their feet, and/or a rip
taking them away. Once they are off their
feet and struggling on the surface, it is
only a rip that is going to take them anywhere.
This must be why there is such a wide bowl
at OB between the shore and the sandbar where
the waves are breaking - I'd always assumed
it was the terrific side currents that are
tidal from and to the Golden Gate, yet I don't
seem to move as much laterally until I get outside.
Mike
Mike
Timothy B. Maddux
Michael Sullivan <gc....@forsythe.stanford.edu> wrote:
>Timothy B. Maddux wrote:
>> In article <390ED7...@forsythe.stanford.edu>,
>> Michael Sullivan <gc....@forsythe.stanford.edu> wrote:
>> >I reasoned that the water near the bottom MUST be still
>> >or even moving the other way - again, no channels.
>>
>> You reasoned correctly -- that return flow is the "undertow."
>
>Tim, is that the honest to goodness real-live
>term for that flow?
Yes, "undertow" is an honest-to-goodness
real-live term used by coastal oceanographers
in papers, public meetings, etc. It's very
important for understanding the dynamics of
sandy bottoms, as you intuited:
>This must be why there is such a wide bowl
>at OB between the shore and the sandbar...
Yes, in very general terms a sandbar is built
up where a balance occurs between the shoreward
pushing of sand by waves and the offshore pushing
of sand by the undertow current.
>When beach rooks talk to each other about watching
>out for the undertow, they are talking about the beach
>washback that can knock them off their feet, and/or a rip
>taking them away.
I can't be held responsible for what rooks (kooks?)
have to say to each other. Unfortunately these
seem to be the same kooks that result in summertime
beach closures and tickets to surfers on the east
coast of the U.S. due to 'dangerous' hurricane surf.
--
.-``'. Tim Maddux, Ocean Engineering Lab, UCSB
.` .`~ Santa Barbara Surfing - http://www.cs.ucsb.edu/~tbmaddux/
_.-' '._ "Let's hang ten for JUSTICE!" -- The Tick
sdbchguy
>
>"Haavard N. Jakobsen" <jako...@protective.no> wrote:
>>
>> I've kind of played with the idea of visual simulation of a
>> breaking wave with a computer as a particle-spring-system,
>> but I guess I would need all the computers in the world to do
>> that. Maybe on a smaller scale, like in glass of water? or a
>> drop of water....
>>
>> -H
>
> While it can be done ( I believe they rented Cray time for
> modelling some of the America's Cup designs and waterflow
> around them) , it is kinda fierce.
> A whole lot of 'packets' of water were individually modelled
> as was their motion. A lesser number of 'packets' and a
> shorter time span might be more approachable.
>
> everybody seems to have : set up the program, start it and
> then ignore it for a few days while it laboriously grinds
> through the calculations.
Computer programs have been developed to simulate the breaking
of a 3-dimensional wave over arbitrary bottom geometry. The
ones that appear to be most successful or useful use an entirely
different approach (known as the Boundary Element Method, BEM,
combined with a mixed Eulerian-Lagrangian approach) from the
"packet approach" that Doc mentiond was used for America's Cup
simulations. The results seem to approximate the real world
quite well. For some references on this approach (and a
bibliography of his publications in applying this technique),
you might check the works of Prof. Stephan Grilli (Univ. of
Rhode Island):
http://www.oce.uri.edu/~grilli/
The code for his two-dimensional simulation model totals around
10,000 lines (I don't know how big the code is for his 3-D
version).
I'm interested in the flow field in the face of a breaking wave
(to supply the boundary conditions for simulatons of surfboard
hydrodynamics) and I hope to run the 2-D model on a modern PC.
In my case, I'll be using the opposite approach to what Doc
suggested--I'll be using one of my old computers for the more
mundane everyday tasks while my newest/fastest/most memory
computer chunks away on the simulation. I can only guess how
long a simulation might take, but based on the time required to
generate a simulation on the mainframe used in Grilli's
simulatios, I'm expecting that Doc has made a pretty good
guess and that it will take a couple of days.
This BEM-Mixed Mode approach works until the plunging jet (the
hydrodynamicist's term for the lip) impacts the sea surface.
Once that happens, the assumptions implicit in the model are no
longer valid and an entirely different approach is probably
required to describe the flow dynamics in the vicinity around
the impact.
Timothy Maddux referred to some work going on at UCSB about this
phase of the problem:
tbma...@wheel.ucsb.edu (Timothy B. Maddux) wrote:
> ...It's all relative -- I don't mean the whole lip has plunged
> down intact to impact the bottom -- so perhaps it's not
> something we can perceive easily when we're trying to paddle
> and duckdive. It's certainly been measured with
> instrumentation and modellers are just starting to get a grip
> on it. In fact, I've got some Tecplot animations from our lab
> of breakers that show some of my coworkers efforts to model
> this stuff. I'll see about posting some of them as movies.
I'd like to encourage Tim to post these numerical simulations
(although perhaps also as a sequence of cross-sections as well
as movies for those of us who are either slow of mind, or have
impared capabilities for viewing movies on the web).
I've had a chance to briefly see some preliminary work by
Fontaine, Landrini, and Tulin (of UCSB), and I think their
modeling effort (while still pretty approximate at the time I
saw it) would go a long to clarifing some of the post-impact
issues that have come up in this thread.
Specifically (IMHO):
What happens as the lip strikes the ocean surface depends
considerably on the relative angle between the plunging lip and
the sea surface at the point of impact.
It appears to me that there are two components to the "bounce"
or "rebound" that has been mentioned in previous posts. One is
that as the lip strikes the sea surface, the impact pressure
(from the momentum of the lip) generates a jet on the shore side
of the impact that looks in some ways like a reflection of part
of the lip off the sea surface and back into the air. The water
in this jet could be either water originally in the lip, or
near/at the sea surface, or a combination of both--that wasn't
clear to me.
Immediately seaward of that upward shooting jet is the downward
moving lip, which continues to plunge some distance below the
sea surface. Behind the lip, a transient hollow is formed in
the sea surface by the entrainment of adjacent ocean water into
the downward plunging jet. Shortly after the impact, one
might expect that this hollow will be filled in from flow from
it's sides and bottom as the transient effects of the lip
diminish over time.
Thus a surfer passing from the shore side of the plunging lip,
through the lip, and then out the back (wave) side of the
descending lip, could expect to experience first an upward
acceleration (the upward jet), then a much more severe downward
acceleration (the plunging jet/lip), then a weaker upward
acceleration (their downward motion from the action of the
plunging jet arrested by their movement into water with a much
weaker vertical motion) as they move out of the jet. This
oscillatory sequence could not only exacerbate the magnitude of
forces that the surfer feels, but also make it more difficult to
respond to them because of the changes in their direction
(e.g. a push-pull-push on the biceps, etc.).
I have a vague recollection of reading a comment (perhaps by
Mike Steward...maybe Neal can verify this) that sometimes there
is a location where the lip energy goes right over you when you
are just inshore from the impact zone. If my memory serves me
correctly, in the UCSB simulations, the greater the oblique
angle between the sea surface and the (shore-side) of the lip,
the more likely the plunging lip will throw up jet of water from
the sea surface, and the faster that jet will be moving toward
shore (to be expected from momentum conservation). I suppose
that given some range of wave sizes, and the right (range of)
angles for this impact, the "reflected" wave might go right over
a surfer--perhaps providing an explaination for the comment I
referred to above.
One more general comment:
Turbulence plays only a very small (i.e. essentially negligible)
role in the breaking of a wave until the final stages (i.e.
after the lip strikes the sea surface). In one or more of the
previous posts, I think I read a reference to the "turbulent
lip", or turbulence in the lip, or something similar. While
turbulence may be present in the lip, it really isn't affecting
the characteristics of the lip trajectory or energy very
much. A more correct analogy would be to think of the lip as a
jet from a garden hose (especially one with a nozzle that makes
a 'fanned out' stream) that is following a ballistic trajectory
that is largely determined by it's initial speed and direction
of motion (at the time it jets out from the crest of the wave in
the case of a breaking wave), and the force of gravity. The
energy in the lip is largely due to the kinetic energy of this
initial motion, plus the kinnetic energy gained as the result of
the conversion of potential energy as the lip "falls" to the sea
surface. The contribution to the energy of the lip by
turbulence (i.e. associated with motions internal to the lip)
would be insignificant. Of course turbulence can play an
important role in the dissipation of the kinetic energy of the
lip that occurs after the jet strikes the sea surface (and
penetrates to some depth).
G
>This must be why there is such a wide bowl
>at OB between the shore and the sandbar where
>the waves are breaking - I'd always assumed
>it was the terrific side currents that are
>tidal from and to the Golden Gate, yet I don't
>seem to move as much laterally until I get outside.
In talking to and surfing with Jeff Kaplan, he said that before
the most recent El Nino years, there was no inner and outer sand
bar at OB, just one bar on the outside.
G
Natural Born Cynic
Michael Sullivan
>
> In article <391139...@forsythe.stanford.edu>,
> Michael Sullivan <gc....@forsythe.stanford.edu> wrote:
> >> In article <390ED7...@forsythe.stanford.edu>,
> >> Michael Sullivan <gc....@forsythe.stanford.edu> wrote:
> >> >I reasoned that the water near the bottom MUST be still
> >> >or even moving the other way - again, no channels.
> >>
> >> You reasoned correctly -- that return flow is the "undertow."
> >
> >Tim, is that the honest to goodness real-live
> >term for that flow?
>
> Yes, "undertow" is an honest-to-goodness
> real-live term used by coastal oceanographers
> in papers, public meetings, etc. It's very
> important for understanding the dynamics of
> sandy bottoms, as you intuited:
This has brought up more questions, and things
that don't make sense to me. Rather than bug
you on AS, can you recommend a good text?
>
> >This must be why there is such a wide bowl
> >at OB between the shore and the sandbar...
>
> Yes, in very general terms a sandbar is built
> up where a balance occurs between the shoreward
> pushing of sand by waves and the offshore pushing
> of sand by the undertow current.
>
> >When beach rooks talk to each other about watching
> >out for the undertow, they are talking about the beach
> >washback that can knock them off their feet, and/or a rip
> >taking them away.
>
> I can't be held responsible for what rooks (kooks?)
> have to say to each other. Unfortunately these
No I make a distinction. Big mama and kids come
to the beach for the first time from St Louis, has
some vague idea that there is great danger for
kids and gives out the general 'watch for the
undertow' warning, keeps an eye out, yells
at them to come in if they get out over their
knees. She's a rook, not a kook.
The kook is the one who gets pulled out once a week.
Both are responsible for hurricane swell beach
closures, just for different reasons. The rooks
are physically posting the signs and passing the
ordinances, the kooks are the reason they're having
to do that.
Mike
Crag T. Bagger
Sullivan <gc....@forsythe.stanford.edu> wrote:
>>
>> I can't be held responsible for what rooks (kooks?)
>> have to say to each other. Unfortunately these
>
>No I make a distinction. Big mama and kids come
>to the beach for the first time from St Louis, has
>some vague idea that there is great danger for
>kids and gives out the general 'watch for the
>undertow' warning, keeps an eye out, yells
>at them to come in if they get out over their
>knees. She's a rook, not a kook.
>
>The kook is the one who gets pulled out once a week.
Then it that case I wish I were a kook! That'd be a lot easier
than paddling. My spots are I guess mostly like yours: lack of
defined channels makes every paddle a battle. Better rips would
be a nice feature.
Crag
sponge
>I have a vague recollection of reading a comment (perhaps by
>Mike Steward...maybe Neal can verify this) that sometimes there
>is a location where the lip energy goes right over you when you
>are just inshore from the impact zone.
That was the "null spot" mentioned in one of the other bullet
items in my query list.
sponge
Paul Richardson
Doc wrote:
> "sponge" <spongeN...@iav.com.invalid> wrote in message
> news:2d4c10dc...@usw-ex0104-032.remarq.com...
> > There are so many dynamics to a breaking wave that you could
> > probably write a book on.
>
> In point of fact, I know of a guy who has a website under construction on
> precisely that, plus a lot more. Currently, the first section deals with the
> terminology and concepts...and I'd have to say that it's at least the
> equivalent of a Survey of Physics course at a good college. Though better
> done and much clearer.
Let us know the URL and when the site will be up
>
>
Haavard N. Jakobsen
"sdbchguy" <sdbchguy...@hotmail.com.invalid> wrote:
> Computer programs have been developed to simulate the breaking
> of a 3-dimensional wave over arbitrary bottom geometry. The
> ones that appear to be most successful or useful use an entirely
> different approach (known as the Boundary Element Method, BEM,
> combined with a mixed Eulerian-Lagrangian approach) from the
> "packet approach" that Doc mentiond was used for America's Cup
> simulations. The results seem to approximate the real world
> quite well. For some references on this approach (and a
> bibliography of his publications in applying this technique),
> you might check the works of Prof. Stephan Grilli (Univ. of
> Rhode Island):
>
> http://www.oce.uri.edu/~grilli/
>
The 3D image was just what I'd expect to get.
Nice! Would propably be good to use for creating
the perfect artifical reef.
-H
Denny Waller
Lots to talk about......
> 1. Duckdiving a breaking wave. Ever notice that if the lip (of
> a medium-sized wave) falls right in front of you, it is still
> easy to duckdive unscathed? It's only after a little while that
> the turbulence works its way really deep. I believe it's
> because the initial impact does not penetrate too deeply. Why?
> Surface tension?
Sorry, very old fashioned. Only know the Turtle.............or the White
Knuckle Watuzi. You no hold on tight, you gonna swim.
<snipped the stuff I should have been learning about while I was just trying
to make the damn wave>
> 5. Spit. Why do waves spit? My guess is that as a tube
> collapses, the compressed energy just shoots out the only
> available opening.
If the wave cannot eat you, like a camel, it spits at you. If nobody is on
the wave, it's just practicing spitting on you.
<snipped due to lack of theory>
> 7. Punching through. We talk about duckdiving a wave lots, so
> I won't go there. However, another useful skill is
> the "Hawaiian Pull-Out" while riding the wave. Any points on
> when to do it so that you come through clean?
In my world (old kine hotdogging) a Hawaiian or Island pullout is a maneuver
performed on the nose when trying to get out of a wave. Is that what you are
referring to Your Spongeship? If I am on the tip and feel that I am not
going to make a section, and do not have enough time to backpeddle for a
kickout (a very important, and apparent lost art used by the leashless), I
find that I can squat and grab a rail while turning the board into the wave.
I usually try to get as high up on the wave as possible, but if it is steep
and tubing, you just do what you can do from the bottom of the wave. But the
idea seems to be to tuck and let the wave pass over you and the end of the
board with you ending up facing outside after the pullthrough.
I too have noticed a phenomenon. As a core B.C.er I surf with the idea of
making every wave or using a maneuver to prevent the momentary separation of
me from my board, such as kicking out or in a worst case scenario,
staightening out and proning. Everything done in the spirit of
preventing.........the Big Swim!
However, sometimes the wave supercedes your plans and throws you into a
section that you know you are not going to get out of. Or sometimes
frivolity takes over and I decide to go down in flames with a Ratsimodo or
crouching head dip. This is when you can't reach the rail or don't want to.
And often times these old tricks surprise the wave and we come out the other
side with a carefree splash of water off the head and shoulders. A true head
dip should involve wet hair, but I digress. Anyway, I have found that if I
have at least one foot with toes over when the wave eats me, no matter how
hard the crunch or big the wave, when I come up, 80% of the time the board
is right there within a stroke or two. No swim. But only when I'm right on
the tip. It doesn't matter if I'm riding Kareem's 10'10" or my 9',12lb Billy
Hamilton. If I'm in the middle of the board or back farther and wipe out,
the wave borrows the board for a while and I do aerobics until we can
rebond. Any explanations?
Thousands of waves ridden...........so few answers.
From the Real Righteous School of Surf Well or Swim Well.
River Rat
Gleshna
>Yes, "undertow" is an honest-to-goodness
>real-live term used by coastal oceanographers
>in papers, public meetings, etc. It's very
>important for understanding the dynamics of
>sandy bottoms, as you intuited:
At the same time, I sincerely doubt that this is the same "undertow" that
visitors from Kansas worry about when entering the ocean.
RichyBob
flek
>At the same time, I sincerely doubt that this is the same "undertow" that
>visitors from Kansas worry about when entering the ocean.
oooh, no no nono....you're talking about the *under-toad*.
Mountain Man
...[trim the digression]...
>I digress. Anyway, I have found that if I have at least
>one foot with toes over when the wave eats me, no matter how
>hard the crunch or big the wave, when I come up, 80% of the
>time the board is right there within a stroke or two. No swim.
>But only when I'm right on the tip. It doesn't matter if I'm
>riding Kareem's 10'10" or my 9',12lb Billy Hamilton. If I'm
>in the middle of the board or back farther and wipe out,
>the wave borrows the board for a while and I do aerobics until
>we can rebond. Any explanations?
>
>Thousands of waves ridden...........so few answers.
G'day Denny, I'll have a go at this for the sake of it, but
please keep in mind I am only looking through the glass darkly,
and could be out of the park altogther ... IMO:
On the nose (you and the board) are more or less committed to
the line, and the further you go back the less commitment
(you and your board) have to it.
On the nose, to manoever fast, you have to step back, and
then physically move (you and/or the board) to another curve.
If you are in the middle of the board I am nowhere about to
say you cannot be locked in and committed to a wave.
What I think can be said is that the system of (you and your
board) are far from committed, and you could, if you wish,
change the direction and course of the 'slide'.
So when you buy a prime slab of Pacific Real Estate, or
go diving for lobsters (as one of the local surfers here calls
it) then you have an entirely different relationship to your
moving board and the wave.
From the nose, if you are pushing
it, then both you are your board are both likely to stay
the seaward side of the remains of the lip, and follow the
remains of the lip to check the lobsters. Because the join
between you and the board is at the nose, and both of you are
travelling like quickly quickly, perhaps its like a spear
and a spear thrower who stick together.
If you have the toes on the nose in a barrel, on the assumption
that the nose is generally lower than the tail, then you too
must be lower and thus (slightly) less prone to collect it by
way of the proverbial overhead smack in the head courtesy of
the lip. Of course were just talking stats here. No matter
whether you are on the nose or over the fin, if your in the
wrong spot your gunna buy it.
In the other instance, in the middle of the board, you are
joined to it from the middle. This is now a good 4 to 5 feet
(with your particular quiver) from the action on the nose,
and uphill from it to boot.
That might represent a significant factor in your review of it.
So if the nose gets nailed first, its gunna give you the big
flick from the middle, and if your up the back further, then
its like the circus see-saw and the clowns. Both of these see
you separated bigtime, unless by chance the board is sent in the
same direction.
So that should be enough for the moment to at least provide
further discussion towards a possible answer in the absence
of anything else. I am after all only guessing.
I think, RR, I have responded more to the bait:
"Thousands of waves ridden ... so few answers".
Some of these (few) answers are gems though ...
"Mackerel skies and mare's tails
make tall ships wear small sails".
>From the Real Righteous School of Surf Well or Swim Well.
>River Rat
Mountain Man
It is very difficult not to be confused regarding these
two terms if pushed to the limit, unless your a "quantum
mechanic".
I am no quantum mechanic. ;-) Perhaps you'd like to clarify the
distinction you draw between the two ... in a cupla paras.
sdbchguy <sdbchguy...@hotmail.com.invalid> wrote:
>Mountain Man <prfbrown...@magna.com.au.invalid> wrote:
>>
>> ...<much snipped--some of which I agree with, some of
>which I don't>...
Mainly because I see this medium of usenet as another method
of leaning things, and if you dont agree with something I have
written I'd appreciate it if you pick me up on it. I do have
an open mind on most things, and dont mind research.
Even in the field of literature ...
>> ...Buzzwords change with the generations and Age, but there is
>> one around today - again in the discipline of physics - called
>> the collapse of the quantum wave function - where the quantum
>> world and the real world finally interface (according to the
>> authors in this field).
>>
>> The dynamics of a breaking or collapsing wave is at the heart
>> of one of the oldest unsolved puzzles of the physical
>> sciences, and has eluded the best scientific minds for
>> hundreds of years.
>
>Let's not confuse the "collapse" of the quantum mechanical wave
>field (or the wave equations describing that field) with the
>actual collapse of a wave within that field.
>
>SDbchguy
Mountain Man
we get into the dynamics of setting them up ....
Bud <bu...@pixi.com> wrote:
>sponge wrote:
>
>> But launching short could possibly land you right
>> where the lip is pitching down, giving you a one-way ride to
the
>> bottom. Anybody know exactly where the ideal landing spot is?
>> This theory would apply to surfers executing a floater with
>> speed.
>
>My .02-
>
>Can't say much about launching, but . . .a loooong,
"section-overcoming" floater
>on an overhead wave is something I wish I could accomplish more
often. For that,
>I would say down the line speed is the key.
Absolutely - and the faster the better ...
(Is there an aquatic terminal velocity???)
Check this ...
>-----------
>While writing this reply, I got carried away writing about my
limited experience
>with floaters and it may not be in line with the thread. Stop
here if you're not
>interested
>-----------
I didn't actually read any further.
I am typing blind. I stopped here and
sent that ascii below on its own ;-)
>When you're riding high & fast. . . perhaps there's no time to
bottom turn and
>hit the lip. . . even a quick floater over a short section can
be an effective
>and satisfying maneuver.
>
>Good surfing to you,
>
>Bud
>
And to you.
This thread has given me plenty to think about.
Thanks to the HI connection.
sdbchguy
>
> Neal (Sponge) wrote:
>> 7. Punching through. We talk about duckdiving a wave lots,
>> so I won't go there. However, another useful skill is the
>> "Hawaiian Pull-Out" while riding the wave. Any points on
>> when to do it so that you come through clean?
>
>
> In my world (old kine hotdogging) a Hawaiian or Island pullout
> is a maneuver performed on the nose when trying to get out of
> a wave. Is that what you are referring to Your Spongeship? If
> I am on the tip and feel that I am not going to make a
> section, and do not have enough time to backpeddle for a
> kickout (a very important, and apparent lost art used by the
> leashless), I find that I can squat and grab a rail while
> turning the board into the wave.
> I usually try to get as high up on the wave as possible, but
> if it is steep and tubing, you just do what you can do from
> the bottom of the wave. But the idea seems to be to tuck and
> let the wave pass over you and the end of the board with you
> ending up facing outside after the pullthrough.
Yup...you described it perfectly! The key elements seem to be to
get the fin free and the nose buried while simultaneously
initiating a turn into the face of the wave. That buried
nose sets up a torque that continues the rotation so that the
board (and rider) align into the flow of the wave as it goes
past and over them.
The first time I saw this maneuver in action was back in the
middle-late 60's when Ricky Grigg brought Phil Edwards to
Black's (also out were Rick Phleger and James Jones (although a
different one from JJ in HI)).
It was a double-overhead SW swell day, throwing WAAAAAAYYYYY
out--and the only place you could get out was at the mushroom
house. As it was obvious that the walls were unmakable,
everybody was riding the semi-shoulders near the mushroom house
(Scripps Canyon). Everyone but Rick, that is.
Rick would take off on those long left walls, trim about 3/8's
of the way back from the nose, and drive for all he was worth
across the face. But of course the waves were breaking too fast
for him to make...so at the last possible moment, he'd do more
or less exactly what you've described and Rick would penentrate
into the face while the wave looped overhead and past.
The only problem was that the board always got sucked back over
and Rick would have to swim in. I think it was just too big and
hollow that day as I later watched him do the maneuver
successfully nearly 100% of the time on less gnarly waves.
Anyhow, when he'd get into the beach, he'd run up north to get
his board, then run full tilt back down to the mushroom
house...shouting: "This is SOOOOOO GOOD!!!" as he'd go by me.
After the first wave, he needn't have ridden any others if
anyone had been filming as every ride was an exact carbon copy
of the first: Take off, trim and drive, Hawaiian pull-out as he
was getting covered, swim to shore, run up the beach, get board,
run down the beach, paddle out. I was worn out just watching
him.
After watching this impressive demonstration of Rick's, I built
a kneeboard that facilitates this type of pull-out. There's a
pic of it at:
http://home.pacbell.net/surfwiz/pantagrl.htm
I've had a lot of fun with it in those super hollow, tubing,
close-out waves that sometimes break in knee-deep water over the
sandbar at Black's on a low tide (I'm too old, and my bones too
brittle now, to do that anymore however -- plus hopefully I'm
a little wiser :-) However, as there was no way I was going to
try that maneuver out on the kind of waves that I watched Rick
ride, I don't know how well it might have worked on them (and
whether one might be able to avoid losing the board each time).
SDbchguy
Timothy B. Maddux
>While writing this reply, I got carried away writing about my
>limited experience with floaters and it may not be in line with
No way. Great details on floaters, Bud, thanks!
--
.-``'. Tim Maddux, Ocean Engineering Lab, UCSB
.` .`~ tbma...@engineering.ucsb.edu
_.-' '._ Santa Barbara Surfing - http://www.me.ucsb.edu/~tbmaddux/
Michael Sullivan
>
> In article <391250...@forsythe.stanford.edu>, Michael
> Sullivan <gc....@forsythe.stanford.edu> wrote:
> >>
> >> I can't be held responsible for what rooks (kooks?)
> >> have to say to each other. Unfortunately these
> >
> >No I make a distinction. Big mama and kids come
> >to the beach for the first time from St Louis, has
> >some vague idea that there is great danger for
> >kids and gives out the general 'watch for the
> >undertow' warning, keeps an eye out, yells
> >at them to come in if they get out over their
> >knees. She's a rook, not a kook.
> >
> >The kook is the one who gets pulled out once a week.
>
> Then it that case I wish I were a kook! That'd be a lot easier
I don't think you mean that. We all go start as rooks,
become groms, reccers, dilletantes, amateurs, maybe
even experts in things we do. Kook isn't part of the
progression of learning, kook is someone who isn't interested
in learning, it's a side trip - though I admit to being
a kook and more than once.
Kooks I have known:
1. 2 Jarines from El Toro swim out with inner tubes into 20 foot
surf (30 ft face) at Newport Pier - wave peaks washing over the
top of the pier. They flip off the guards who are yelling
at them to come in. Both did ICU time at Hoag after rip takes
them into the pier pilings and followup set runs them into the spin
cycle inside there.
2. Couple guys try to top Shasta on warm spring day. Hiked up with
shorts
and Tshirts and day pack. Storm stuck bodies up there for two
days.
3. Group of guys take yakking lessons together and go down a
couple of the fun runs on the American over a year. They launch
on normally safe South Fork during heavy floods a couple
years ago. had to pull rescue units from flooded homes in
Valley to find them.
4. Snowboarders go down trails by their lonesome clearly marked
Do Not Enter - bodies recovered in spring.
> than paddling. My spots are I guess mostly like yours: lack of
> defined channels makes every paddle a battle. Better rips would
> be a nice feature.
Where is that Crag? OB is not a regular spot for me, the
spots I frequent are cake swimouts relatively - Pacifica,
Montara, Half Moon Bay.
Mike
Crag T. Bagger
Sullivan <gc....@forsythe.stanford.edu> wrote:
>Crag T. Bagger wrote:
>>
>> In article <391250...@forsythe.stanford.edu>, Michael
>> Sullivan <gc....@forsythe.stanford.edu> wrote:
>> >>
>> >> I can't be held responsible for what rooks (kooks?)
>> >> have to say to each other. Unfortunately these
>> >
>> >No I make a distinction. Big mama and kids come
>> >to the beach for the first time from St Louis, has
>> >some vague idea that there is great danger for
>> >kids and gives out the general 'watch for the
>> >undertow' warning, keeps an eye out, yells
>> >at them to come in if they get out over their
>> >knees. She's a rook, not a kook.
>> >
>> >The kook is the one who gets pulled out once a week.
>>
>> Then it that case I wish I were a kook! That'd be a lot
easier
>
>I don't think you mean that.
I was sorta joking. Sorry I'll make sure I ;) next time I say
that.
> We all go start as rooks,
>become groms, reccers, dilletantes, amateurs, maybe
>even experts in things we do. Kook isn't part of the
>progression of learning, kook is someone who isn't interested
>in learning, it's a side trip - though I admit to being
>a kook and more than once.
Me too.
>Kooks I have known:
>1. 2 Jarines from El Toro swim out with inner tubes into 20 foot
>surf (30 ft face) at Newport Pier - wave peaks washing over the
>top of the pier. They flip off the guards who are yelling
>at them to come in. Both did ICU time at Hoag after rip takes
>them into the pier pilings and followup set runs them into the
spin
>cycle inside there.
Blatant hardcore kookery and plenty painful, I guess. Reminds me
of a family of 3 noticeably overweight tourons (mom, dad, and a
10 or 12 year old boy) who parked their zoniemobile at OB (SD)
during a big storm swell that had closed the pier. They
climbed over the berm and approached the water with some walmart
boogie boards with no leashes or fins. Nobody was out in the
water (hardcore VAS) and they started walking out right in front
of the surf traffic control tower, apparently
*completely* oblivious to both the surf itself and the lifeguard
on the PA repeatedly "recommending" that nobody enter the water
unless they were expert ocean swimmers with fins. After a few
minutes they seemed to come out of their daze and retreated up
the beach, and the lifeguards stowed their churchills and
battened down the cover on the zodiac.
>2. Couple guys try to top Shasta on warm spring day. Hiked up
with
>shorts
>and Tshirts and day pack. Storm stuck bodies up there for two
>days.
Now you're getting close to my territory. I love doing
ultralight solo one-day ascents of 14ers and high 13ers.
[snipped other fine examples of spectacularly bad judgement]
>> than paddling. My spots are I guess mostly like yours: lack
of
>> defined channels makes every paddle a battle. Better rips
would
>> be a nice feature.
>
>Where is that Crag?
Oh, here and there around SD County, and points south. I favor
hollow beachbreaks, which can be challenging paddles in sizeable
but short-period conditions - when the currents invariably run
hard alongshore rather than in the more useful direction.
BTW thanks to Neal and all participants on this thread, it is
very interesting.
Crag
G
Waller" <Pnep...@aloha.net> wrote:
>
>In my world (old kine hotdogging) a Hawaiian or Island pullout
is a maneuver
>performed on the nose when trying to get out of a wave.
Snipped Denny's description of a Hawaiian pullout...I've never
heard of or seen this done from the nose of a surfboard, but
sounds like fun to witness one. I'd imagine it could only be
done from the nose on smaller waves though.
>Anyway, I have found that if I
>have at least one foot with toes over when the wave eats me, no
matter how
>hard the crunch or big the wave, when I come up, 80% of the
time the board
>is right there within a stroke or two. Any explanations?
Despite, Mountain Man's poetic explanations, I will offer my
brief words as well.
In my limited experience, when eating it while on the nose of
the board, your weight is so far forward that the board
effectively pearls.
So with the nose down/tail up, the boards buoyancy stops its
foward advance and propels it backwards enough to overcome the
forward motion of the wave's energy, thus leaving your board
close by when you surface.
Gioni
sdbchguy
>
> It is very difficult not to be confused regarding these
> two terms if pushed to the limit, unless your a "quantum
> mechanic".
>
> I am no quantum mechanic. ;-) Perhaps you'd like to clarify
> the distinction you draw between the two ... in a cupla paras.
I think that once I get started on any topic, it's
impossible for me to stop "...in a cupla paras... :-)
As far as a quantum mechanical "collapse", there's a number of
different ways that the word might be used in regard to the
quantum mechanical wave field. I'll try to describe what I think
(IMHO) might be the most likely usage of the term within the
context you indicated. Since I'm certainly not an expert in
elementary particle or gravitational quantum mechanics, I won't
guarantee that I'm either correct, or complete. Moreover, I'll
be attempting to illustrate my points through the use of
analogies, or quoting others who know far more about the subject
tha I do.
Let's start out with quantum mechanics. As Ian Steward notes in
his book "Does God Play Dice":
"Quantum mechanics is the modern physics of the universe at
atomic scales of measurement. In quantum mechanics, quantities
such as energy are not continuous: instead they come in discrete
lumps, or 'quanta'. The size of a single quantum is desperately
small, given by a tiny number known as Plank's constant. And
particles aren't particles at all, but a wave-particle duality
described by a quantum-mechanical wave function."
He continues:
"It isn't easy to interpret quantum mechanics at a human level.
Indeed, one school of thought argues that there's no point in
trying to do so, because the quantum world and that of our
senses have nothing in common. Other's disagree, and offer
interpretations anyway. In a popular one, the wave-function
represents not the state of a particle, but a superposition of
all possible states; and when an observation is made, the
wave-function 'collapses' to a single state. Before this
collapse, it represents the probability that the system will be
found in a given state."
So in this interpretation, the "collapse" of the wave-function
doesn't change the state of the particle, per se, it only
changes the probability that the particle is in a specific
state (of many possible states).
FWIW, Stewart doesn't like this interpretation very much. Nor,
he notes, did Albert Einstein. He does concede, however, that
the interpretation does yield results which agree with the
real-world (i.e. at our scales of awarness, rather than at the
atomic level).
There is at least another use of the word 'collapse' that is
both similar to, and yet profoundly different from, the use
above. Namely that the wave function does describe the state of
the particle, rather than a probability. The quantum mechanical
equations govern the dynamics of a system at the atomic (and
presumably sub-atomic) scales of energy (and the associated
scales of length and time). Presumably they are also applicable
at the energy, length, and time-scales that are within our range
of perceptions as well. However, at these macroscopic scales,
the wave function takes on properties such that the dynamics of
the particle can be described by Newtonian mechanics (or
relativistic mechanics, if appropriate) to a very high degree of
accuracy. So as the energy, length, and time-scales are
increased from the atomic level to the 'real-world' level, there
comes a point where the quantum mechanical equation(s)
effectively 'collapse' into the equations of Newtonian
mechanics. So in this terminology there is no real change in the
dynamics of the particle, only how those dynamics can be
described (e.g. their representation in equations).
By way of illustration (by analogy) of the latter, consider the
equation for the speed of translation of a surface gravity
wave (e.g. an ocean wave). This equation is rather complicated
in appearance and involves transcendal functions that depend
on both the wave-length of the wave and the depth of the water.
However, if the water is very deep in comparison with the
wavelength of the wave, this complicated equation can be
approximated to a high degree of accuracy by a much simpler
equation...the so-called equation for a 'deep water' wave.
Conversely, if the water is very shallow compared with the (deep
water) wavelength of the wave, the exact equation can be
represented with good accuracy by a much simpler
equation...the 'shallow water' wave equation. So the equation
for the speed of the gravity wave can be said to 'collapse' into
the deep water equation as the wave moves into deep water, or,
conversely, to 'collapse' into the shallow water equation as the
wave moves into shallow water.
In the later case, the wave can ultimately be expected to break
as the water shoals, and one might be inclined to call it a
'collapse' of the wave when the water becomes shallow enough for
that to occur. However, this 'collapse' is separate from the
'collapse' of the wave equation into it's shallow water form,
and this breaking generally occurs much later in the wave's
travel than where the wave equation 'collapses' into it's
shallow water approximation.
Mountain Man <prfbrown...@magna.com.au.invalid> wrote:
>
>> sdbchguy <sdbchguy...@hotmail.com.invalid> wrote:
>>>
>>> ...<much snipped--some of which I agree with, some of
>>> which I don't>...
>
>
> Mainly because I see this medium of usenet as another method
> of leaning things, and if you dont agree with something I have
> written I'd appreciate it if you pick me up on it. I do have
> an open mind on most things, and dont mind research.
First of all, please note that I said "...some of which I
don't...", not "...all of which I don't..."
I guess my primary disagreement is with the emphasis that you
seemed to place on the importance of turbulence as regards
surfing. I don't disagree that it is fundamentally important to
the ultimate fate of the wave, or if you like to play around in
the consequences of the lip striking the ocean surface, and
certainly what you experience in 'pushing' through waves (or
white water).
However, I do disagree when you say that:
> This problem - the scientific specifications of turbulence -
> is long-standing and should be emminently respected. On the
> other hand surfers deal with this physical phenomenom every
> day, and revel in its play. Perhaps then, the new
> understanding of old problems will emerge through the heart
> and soul of surfing and through the experience of STOKE.
IMHO, this view gives too much importance to the final stages of
a wave breaking...the dissipation of it's energy through the
generation of turbulence.
Most surfers that I know don't revel in, nor are they stoked by,
playing with the turbulence generated by a breaking wave. As
partial evidence, note the number of posts requesting advice in
how to survive this turbulence (e.g. how to duck dive). What the
average surfer seems to revel in is playing on the face of,
and/or being tubed by, the portion of a breaking wave that is
not turbulent (although the more accomplished surfers may
delight in playing with the 'shockwave', or 'foamball', or
perhaps for those with masochistic leanings, even pushing
through waves, getting tumbled after going over the falls,
etc.).
> If you were to discover the complete dynamics of a breaking
> wave, sponge, then you would receive the Nobel Prize in
> physics.
That's certainly true as you have used the word
"complete"...which ultimately implies that one has formulated
and solved the "equations of the universe" (of which
relativistic gravitational quantum mechanics is a part).
In a less literal (and probably more common) interpretation, I
presume that you are referring to: (1) solving the Newtonian
equations of motion for the bulk motions of a surface gravity
wave and, (2) completely describing the evolution of turbulence
generated by the breaking wave.
I don't think anyone is going to win a Nobel prize for obtaining
solutions for the bulk motions of the wave. On the other hand,
achieving a complete description of turbulence may very well
earn someone it. But I suspect that the chance that someone will
achieve that comprehensive description while studying breaking
waves is pretty remote since there is so much more to turbulence
than would probably be found in just a breaking wave.
So, again, I take issue with the statement that:
> The dynamics of a breaking or collapsing wave is at the heart
> of one of the oldest unsolved puzzles of the physical
> sciences,...
..but don't disagreement with your statement that turbulence:
> "...has eluded the best scientific minds for hundreds of
> years. Apparently the physicist Heisenburg gave up the study
> of turbulence (because it was far too difficult) and
> instead studied atomic physics, where he became well known.
SDbchguy
Ron Taylor
Denny Waller <Pnep...@aloha.net> wrote in message
news:BdyQ4.2609$5i7.2...@news.aloha.net...
> Aloha Kauai Boy,
>
> Lots to talk about......
> In my world (old kine hotdogging) a Hawaiian or Island pullout is a
maneuver
> performed on the nose when trying to get out of a wave. Is that what you
are
> referring to Your Spongeship? If I am on the tip and feel that I am not
> going to make a section, and do not have enough time to backpeddle for a
> kickout (a very important, and apparent lost art used by the leashless), I
> find that I can squat and grab a rail while turning the board into the
wave.
> I usually try to get as high up on the wave as possible, but if it is
steep
> and tubing, you just do what you can do from the bottom of the wave. But
the
> idea seems to be to tuck and let the wave pass over you and the end of the
> board with you ending up facing outside after the pullthrough.
This manoeuvre is still being done here in Oz, occasionally by an elderly
gent that I know very well, much to the bewilderment of some of the younger
generation (50 years of age and younger).
Ron Taylor
dontsaymuch
Timothy B. Maddux
Haavard N. Jakobsen <jako...@protective.no> wrote:
>I've kind of played with the idea of visual simulation of a breaking
>wave with a computer as a particle-spring-system, but I guess I would
>need all the computers in the world to do that.
Nah, you just need to approximate. Bigger 'particles'
of water, about the size of baseballs, and oh yeah,
tweak its physical properties so that you don't have to
simulate as rapidly, and you can get some interesting
graphics after a week on a P-III or a day on a
multiprocessor workstation.
--
.-``'. Tim Maddux, Ocean Engineering Lab, UCSB
.` .`~ http://www.me.ucsb.edu/~tbmaddux/
_.-' '._ "From the essence of pure stoke springs all creation."
Timothy B. Maddux
sponge <spongeN...@iav.com.invalid> wrote:
>Similarly, when a lip impacts the water, lots of water is
>bounced back. This impedes the rest of the falling lip,
>allowing more time to skirt under before the turbulence gets
>deeper.
The lip is moving forward and down, the bounce is
forward and up, they don't interact in that kind
of a direct fashion. It's more a matter of it
taking some time for the lip to penetrate fully,
due to that bounce up, the inertia of the relatively
still water into which the lip is plunging, the initial
thinness of most lips, and the forward motion of the
wave pushing the lip's 'launch point' and 'landing point'
forward.
There hasn't been much talk yet about air. As the lip
falls it's getting sheared off and mixed with air, so
what hits you in the trough is a mixture of water and air.
So, when it's offshore and the lip is getting heavily
aerated, does it not hit as hard when the winds are calm?
Doc
"Timothy B. Maddux" <tbma...@alumni.caltech.edu> wrote in message
news:8f5ct5$k...@gap.cco.caltech.edu...
> In article <04056000...@usw-ex0103-086.remarq.com>,
>
> There hasn't been much talk yet about air. As the lip
> falls it's getting sheared off and mixed with air, so
> what hits you in the trough is a mixture of water and air.
Uhm...the leading edge, certainly, but what follows tends to be pretty pure
water.
> So, when it's offshore and the lip is getting heavily
> aerated, does it not hit as hard when the winds are calm?
Hmmm.... I'm thinking I've noticed a similar effect, but somehow I don't
think aeration is it.
Now, a sufficiently strong offshore might hold a wave up until the work of
holding that face up against gravity has used up a lot of the energy in the
wave. Then it doesn't send over the volume of water that it might, were the
wind calm, and it sometimes just falls straight down the face. As an
illustration: http://www.capecod.net/~fbates/NEWCOMB3.JPG
Another couple of examples: http://www.capecod.net/~fbates/smokr.jpg : a
pretty strong offshore.
http://www.capecod.net/~fbates/WINTER.JPG : the same place, but less of an
offshore. Note how the impact of the lip is producing a much higher splash
.
It also would throw out further, which has two effects. Not only does the
lip have more distance to pick up downward velocity, it probably has some
velocity component in the direction of shore which might add something to
how hard it hits. For example, consider
http://www.capecod.net/~fbates/biteme.jpg . Definitely that lip isn't
hitting the trough perpendicular, it's hitting at an angle with a
substantial horizontal velocity component.
flek
<snipped loads of info>
i just want ya'll to know that while i'm not contributing (as i am humbled by
the display of hydrodynamics and physics), I'm reading this stuff as if there'l
be a test....
carry on, flek's taking notes....
Southoz
"Mountain Man" <prfbrown...@magna.com.au.invalid> wrote in message >
> "Mackerel skies and mare's tails
> make tall ships wear small sails".
>
How about
Red sky at night,
Surf Warning in the morning!
.
.
.
.
.
.
.
.
.
.
Yeah I know, call it poetic license ;-)
Southoz.
Southoz
> > falls it's getting sheared off and mixed with air, so
> > what hits you in the trough is a mixture of water and air.
>
> Uhm...the leading edge, certainly, but what follows tends to be pretty
pure
> water.
>
> > So, when it's offshore and the lip is getting heavily
> > aerated, does it not hit as hard when the winds are calm?
Wouldn't it also be possible that the wind is thickening the lip by holding
more water back as the wave tries pushing more forward, although some is
also pouring up and over in the 'hairdo'. Then because the wave has moved
further into shallower water before the moment of impact the wave is going
to break even harder and thicker than a calm day. Whether you can get into
the wave or not is the next problem.
> Now, a sufficiently strong offshore might hold a wave up until the work of
> holding that face up against gravity has used up a lot of the energy in
the
> wave.
It is the energy of the wind that is holding the face up, unless the wind is
so strong it rips half the thing off and so decreases the wave height,
otherwise the wind is 'lifting' the wave crest and increasing the potential
energy, also leading to a more powerful impact.
>Then it doesn't send over the volume of water that it might, were the
> wind calm, and it sometimes just falls straight down the face. As an
> illustration: http://www.capecod.net/~fbates/NEWCOMB3.JPG
>
> Another couple of examples: http://www.capecod.net/~fbates/smokr.jpg : a
> pretty strong offshore.
> http://www.capecod.net/~fbates/WINTER.JPG : the same place, but less of an
> offshore. Note how the impact of the lip is producing a much higher
splash
Nice photos, but so difficult to compare the concepts here with a few
photos. Too many variables.
> It also would throw out further, which has two effects. Not only does the
> lip have more distance to pick up downward velocity, it probably has some
> velocity component in the direction of shore which might add something to
> how hard it hits. For example, consider
> http://www.capecod.net/~fbates/biteme.jpg . Definitely that lip isn't
> hitting the trough perpendicular, it's hitting at an angle with a
> substantial horizontal velocity component.
Once again I think the action of the wave breaking in shallower water on the
strong offshore day compared to a glass day is the major factor in the power
of the lip impact.
Southoz.
Wavslav
>i just want ya'll to know that while i'm not contributing
I just want you to know that there is a difference between posting and
contributing. That distinction has thusfar eluded you.
>flek's taking notes...
As it should be
Doc
"Southoz" <sou...@yahoo.com> wrote in message
news:8f5pde$ba...@gamgee.cc.flinders.edu.au...
>
> > "Timothy B. Maddux" <tbma...@alumni.caltech.edu> wrote in message
> > >
> > > There hasn't been much talk yet about air. As the lip
> > > falls it's getting sheared off and mixed with air, so
> > > what hits you in the trough is a mixture of water and air.
> >
Doc
> > Uhm...the leading edge, certainly, but what follows tends to be pretty
> pure
> > water.
> >
Tim
> > > So, when it's offshore and the lip is getting heavily
> > > aerated, does it not hit as hard when the winds are calm?
>
Southoz
> Wouldn't it also be possible that the wind is thickening the lip by
holding
> more water back as the wave tries pushing more forward, although some is
> also pouring up and over in the 'hairdo'. Then because the wave has moved
> further into shallower water before the moment of impact the wave is going
> to break even harder and thicker than a calm day. Whether you can get into
> the wave or not is the next problem.
Just to clarify; I wouldn't want Tim to take the blame for my half baked
theories.
>
>
> > Now, a sufficiently strong offshore might hold a wave up until the work
of
> > holding that face up against gravity has used up a lot of the energy in
> the
> > wave.
>
> It is the energy of the wind that is holding the face up, unless the wind
is
> so strong it rips half the thing off and so decreases the wave height,
> otherwise the wind is 'lifting' the wave crest and increasing the
potential
> energy, also leading to a more powerful impact.
Ah, but it's not! It's both the wind and the wave in action at once. Energy
is being used up (work) by both wind and and wave, similar to a powerboat
towing a sailboat backwards, or a brake left engaged in a vehicle. The wave
has greater power, in most cases (rate of energy use per unit of time) so it
proceeds forward.
But the energy of each wave is finite: there's only so much in each wave.
The wind has less power, but it's constant, not coming per wave (yes, this
is a gross oversimplification, but for this situation it will do) in
...well, I'd love to use the term 'packets' but it'd be confusing as we've
used it in a very different situation. In any event.... those tonnes of
water are being lifted up by the wave's power and if instead of immediately
coming over those tonnes of water stay up there just a little longer a
substantial portion of the wave's energy is being used in holding that water
up aginst both the wind and gravity. As the energy is used it then has less
to put into throwing out a thick lip and throwing it far down the face. It
has less punch, though likely a steeper and taller face, which means more
speed is available to a surfer on that wave.
But the speed available comes from the ability to use more height, not from
any power the wave has or hasn't got.
>
> >Then it doesn't send over the volume of water that it might, were the
> > wind calm, and it sometimes just falls straight down the face. As an
> > illustration: http://www.capecod.net/~fbates/NEWCOMB3.JPG
> >
> > Another couple of examples: http://www.capecod.net/~fbates/smokr.jpg : a
> > pretty strong offshore.
> > http://www.capecod.net/~fbates/WINTER.JPG : the same place, but less of
an
> > offshore. Note how the impact of the lip is producing a much higher
> splash
>
> Nice photos, but so difficult to compare the concepts here with a few
> photos. Too many variables.
I agree- I was using those for illustrations only. I was of two minds about
using photos: on the one hand they can illustrate a point very well, on the
other the photos and the waves in those photos are a tiny subset of all
conditions.
>
>
> > It also would throw out further, which has two effects. Not only does
the
> > lip have more distance to pick up downward velocity, it probably has
some
> > velocity component in the direction of shore which might add something
to
> > how hard it hits. For example, consider
> > http://www.capecod.net/~fbates/biteme.jpg . Definitely that lip isn't
> > hitting the trough perpendicular, it's hitting at an angle with a
> > substantial horizontal velocity component.
>
>
> Once again I think the action of the wave breaking in shallower water on
the
> strong offshore day compared to a glass day is the major factor in the
power
> of the lip impact.
Again, you're right on that. That last was to illustrate a lip hitting with
a certain horizontal component to its velocity, not as a comparison.
My own thinking is that the bottom contour and depth has the greatest effect
on how a wave breaks.
And it occurs to me that while we have discussed wave size ad infinitum
here, the power of a wave is something important. And harder to quantify. It
seems that what's going on is the strict definition of power: work done per
unit of time while the wave is breaking. That in turn involves how much
energy is there to be used and how fast it's used.
Jeez, Neal, look what ya went and started......
Doc
Mountain Man
>> > > There hasn't been much talk yet about air.
...[trim]...
Air, water, earth and sunshine (fire) -
the ancient elements of (terrestrial) nature.
AEON. (not Neon).
couldn't resist.
But as far as first approximations to a (unified) description of
nature, it is surprising what such elements, and their
interaction in nature, would instruct.
>It seems that what's going on is the strict definition of
>power: work done per unit of time while the wave is breaking.
>That in turn involves how much energy is there to be used
>and how fast it's used.
Never ceases to amaze me when I start thinking about waves
as energy transfer mechanisms. They say the earth rings like
a bell with the Schumann resonance but if it does, surely
there is a contribution to this by the constant pounding upon
the shores? How much energy is being so delivered world-wide
per minute?
This energy, first delivered to the oceanic water by the energy
in the wind (and before than from the energy of the sunshine), is
transported to the end of its road by the groundswell (or rather
*as* the groundswell), where is changes form again.
At the boundary of the water and the earth - at the coast - it is
released from its form by the breaking of this water on the
earth. The sound of a raging surf has a distictive ring to it,
and the ground a distinctive rumble.
>Jeez, Neal, look what ya went and started......
>
>Doc
OnYa sponge!
And that's AEON, not NEON, NeoN.
Timothy B. Maddux
Doc <jfm...@capecod.skipthe.canned.meat.net> wrote:
>It's both the wind and the wave in action at once... the
Yes, I've watched strong offshores come on and blow small
waves (2' faces) away to nothing. Also, the offshore wind
doesn't boost the energy of the wave, but it does steepen
and shorten the wave, holding it back and forcing it to
release that energy more quickly.
My question was spurred more by a reference sdbchguy posted
and other models, all of which have pure blue lips, whereas
if you look at any picture they're white and foamy as they
throw out, more so in an offshore.
>> > It also would throw out further, which has two effects.
>> > Not only does the lip have more distance to pick up downward
>> > velocity...
Negligible. It would have to throw out either from a greater
height or into a shallower trough. The fall velocity will
only increase over vertical distance.
>> > it probably has some velocity component in the direction of
>> > shore which might add something to how hard it hits.
Probably true. That in turn will affect the splash-up
on impact that Neal alluded to.
>And it occurs to me that while we have discussed wave size ad infinitum
>here, the power of a wave is something important. And harder to quantify. It
>seems that what's going on is the strict definition of power: work done per
>unit of time while the wave is breaking. That in turn involves how much
>energy is there to be used and how fast it's used.
Yes. Real world application for surfers: ever notice how a burgery
wave will build up slowly as it breaks, while a pitching wave will
explode into whitewater and subside rapidly? How the energy is expended
and at what rate makes a big difference in where you want to be if you're
duckdiving.
>Jeez, Neal, look what ya went and started......
Beats the trolling, though.
Tom Keener
<prfbrown...@magna.com.au.invalid> wrote:
>Never ceases to amaze me when I start thinking about waves
>as energy transfer mechanisms. They say the earth rings like
>a bell with the Schumann resonance but if it does, surely
>there is a contribution to this by the constant pounding upon
>the shores? How much energy is being so delivered world-wide
>per minute?
White noise. And sometime in the 21st Century, Earth will be creating
so much noise that all the intelligent civilizations in the Universe
are going to gang up and tell us to "Shut the Fuck Up!"
With an OrbBlaster, of course.
Tom Keener
keensurf_at_cts_dot_com
flek
>
>>Never ceases to amaze me when I start thinking about waves
>>as energy transfer mechanisms.
do any of you folks know a formula to get close the finding the weight of the
water displaced by a wave of a certain size?...say the difference of weight due
to surface area above average sea height...
how much does that thar wave weigh?...and how much energy is it taking to roll
that amount of water that high up? what would it look like to put that in
terms i could understand?...like how much electricity would that generate in
perfect machine?
sponge
>Jeez, Neal, look what ya went and started......
Ain't it grand? <grin>
sponge (also overwhelmed by the voluminous, detailed, technical
responses)
sponge
>Aloha Kauai Boy,
Howzit Denny! Sorry I didn't respond in a timely manner.
>> 7. Punching through. We talk about duckdiving a wave lots,
so
>> I won't go there. However, another useful skill is
>> the "Hawaiian Pull-Out" while riding the wave. Any points on
>> when to do it so that you come through clean?
>
>In my world (old kine hotdogging) a Hawaiian or Island pullout
is a maneuver
>performed on the nose when trying to get out of a wave. Is that
what you are
>referring to Your Spongeship?
Yup yup!
<snipped some neat personal experiences by the Hanalei River Rat>
Tangentiating a little bit, in ES2, Wingnut does a lot of
different things to keep his board close, including kicking the
board out and over the whitewater after a ride. Pretty gnarly
stuff in crowds.
Any other good ways of punching through without having to do the
big swim? (besides also the tail stall and proning out)
>Anyway, I have found that if I
>have at least one foot with toes over when the wave eats me, no
matter how
>hard the crunch or big the wave, when I come up, 80% of the
time the board
>is right there within a stroke or two. No swim...
Gotta make sure you have lots of wax and strong, monkey grip
toes. However, doing this can lead to serious leg cramps.
sponge
cor...@mediaone.net
> "Doc" <jfm...@capecod.skipthe.canned.meat.net> wrote: <snip>
> >Jeez, Neal, look what ya went and started......
>
> Ain't it grand? <grin>
Yes, it really is! Loving trying to follow and comprehend the small
amount of it that I can....and for sure am gonna go back to Deja
sometime after I've read more of the Book of Waves and try to understand
these threads more indepth! (Also loving Mountain Man's Solunar Theory
thread and Surfergirl's thread relating to signs that tell of good surf
to come and related threads).
Thank you Neal and all!....welp back to lurkin' these threads and
stretchin' my brain to try to follow them.....and mighty glad for all of
'em!
Dee Dee
Doc
"flek" <flek...@aol.compound> wrote in message
news:20000508145610...@ng-ff1.aol.com...
> ><prfbrown...@magna.com.au.invalid> wrote:
> >
> >>Never ceases to amaze me when I start thinking about waves
> >>as energy transfer mechanisms.
>
> do any of you folks know a formula to get close the finding the weight of
the
> water displaced by a wave of a certain size?...say the difference of
weight due
> to surface area above average sea height...
You ask a very good question. It's interesting to take this one on.
Okay,to start with, a fairly easy conversion is this: one yard across, one
yard high, one yard deep is close to a ton of water. In meters this works
out even closer.
Now, lets say this chunk of water is lifted up a meter, in one second. .
Against gravity , which is 9.8 meters per second squared . Yes, I'm making
this easy. It's a sample problem.
Warning, we are gonna do some math here. Those who dislike math, this might
be a wonderful time to check the 'troll' threads..... We're also gonna do
metric. I know Flek was in the Corps, so he understands metric. Anyhow......
Breaking out my old physics 101 textbook to be sure I don't screw this up;
Work is defined as Force exerted over a Distance:
W=F * deltaX
So, what's the force. (ObiWan, help me....naah, too easy )
Well, in this case it's the mass of the water times gravity. 1000 kilograms
x 9.8 meters/second (squared)
(9.80665 meters/second (squared) is the book definition, but lets get fuzzy
with this. A cubic meter of seawater has more than 1000 kilograms mass
too....fake it, it sorta evens out if you round one off high and the next
one off low by about the same amount)
Call it 9800 Newtons, because in the metric system has that handy unit for
kg*meters/second (squared) called the Newton.
Now, that force is what's opposing the wave moving the water upwards. And
that move is one meter in length: the delta X, which means the change
(delta ) in position (X)
So, we multiply it through and get 9800 Newton-meters (that's a hyphen, not
a minus sign). There's a unit in metric for those Newton-meters too, namely
the Joule.
9800 Joules, per cubic meter going up one meter . In one second. 9800
Joules/second
"Okay", you're saying, "Doc, you baldheaded old ______, all you have given
me is a number and a word. Fat lot of good that is."
So far, yeah. But now that we have 9800 Joules (in one second) we can sneak
into a set of conversion tables. Joule/seconds to whatever you like.
For instance.
1 Joule/second =
0.00134 horsepower
1 Watt
So that our 9800 Joules that happen in one second translate to (where IS
that damned calculator )
9800 <enter> 0.00134 <*> 13.13 horsepower ( I use a Hewlett Packard
calculator )
or 9.8 kilowatts
And that's just for one lousy little meter-long section of a wave that's not
especially big, something like a meter and a half high (uh huh, the shape of
that piece of wave is kinda like the roof of a house, so we go with 'about a
meter and a half' to get a volume of a cubic meter...in other words, we
faked it again).
Consider a three meter wave, fifty meters long (okay, 1.5 meters and 25
long, Hawaiian. Picky, picky, picky ) Something on the order of 200 times
that work being done to lift that lip up along that distance. I say on the
order of, not 'exactly'. as you have to consider the shape of the wave and
all, but you get the idea. You're looking at enough power there to run a
half dozen semi trucks flat out, or run a thousand tablesaws or about 20,000
100 watt lightbulbs ....... or the amplification system of the Electric
Bagpipes.
You get into the power happening at Mavericks or something like Neal's
Waimea Shorebreak photo and it kinda boggles the mind. And gives you an idea
of how come big waves bash big ships around.
And there are other things going on, work being done by the wave, on all
sorts of other things. This is a simplified example...good thing, 'cause
otherwise I couldn't do it.
>
> how much does that thar wave weigh?...and how much energy is it taking to
roll
> that amount of water that high up? what would it look like to put that in
> terms i could understand?...like how much electricity would that generate
in
> perfect machine?
Okay, that may get you started...... and it's not the worst thing you could
be doing, while sitting on the beach, doing a little math in the sand.
Doc..... lost without a RPN calculator.....
>
>
sponge
explanation of the energy of a wave:
You must've been a great TA--good explanation.
One nitpicky thing: Where did you pull the one second out from
to get the energy (work per unit time)?
Tangentiation: There could be a case to quantify the horizontal
component of kinetic energy from the wave, although it probably
would be a fraction of the vertical energy. Not sure how much
energy is actually being created relative to a static location
(say, spot x over the reef or sand).
Example: http://www.iav.com/~sponge/images/snaked.jpg
Southoz
While you had the calculator out and we were all lazing around asking the
questions, you mentioned that seawaters' mass is so much etc as compared to
fresh water (at some temperature, no doubt) soooo.... do you feel like
quantifying the effect of water temperature on wave power ? (Inquiring
minds and all...)
>Jeez, Neal, look what ya went and started......(Doc)
Southoz.
"Doc" <jfm...@capecod.skipthe.canned.meat.net> wrote in message
news:RfIR4.3497$
Doc
> Doc,
>
> While you had the calculator out and we were all lazing around asking the
> questions, you mentioned that seawaters' mass is so much etc as compared
to
> fresh water (at some temperature, no doubt) soooo.... do you feel like
> quantifying the effect of water temperature on wave power ? (Inquiring
> minds and all...)
>
> >Jeez, Neal, look what ya went and started......(Doc)
>
> Southoz.
Oh gawd..... lets see.
Density of seawater as a function of temperature. That's really the only
temperature dependant factor, I'd think. If it's denser, it has more
momentum and kinetic energy per volume, given identical accelerations and
such.
Of course, that density depends on where the seawater is. The Red Sea is
denser than, for instance, the Atlantic. More salt in it, so a liter of Red
Sea water has a skosh more weight than a liter of, for instance, Arctic
Ocean water where there's a fair amount of melted glacier in it and so less
salt. If you measure their densities at a standard temperature, the Red Sea
is denser than the Arctic Ocean.
(stalling for time...... where IS that damned reference book...)
Okay...the CRC Handbook of Chemistry and Physics. Leave one open on your
coffee table and blow your visitor's minds.
And, in here is Properties of Water in the range 0-100 C. Including
densities as a table. Fresh water densities, but we can use it for this.
10 C- density is 0.99970 Kg/liter
20C - 0.99821 Kg/liter
30C - 0.99565 Kg/liter
40C - 0.99222 Kg/liter.
So, the water gets a touch less dense as it gets hotter. Reasonable enough,
though as I get hotter I get pretty dense indeed.
But, that's fresh water. Sea water has salts in it. And as it gets hotter,
it evaporates more. Which leaves a higher concentration of salts behind, and
so warm oceans (like the Red Sea ) tend to be saltier than cooler oceans.
And so I'd have to say that the effect of temperature on the density of
seawater is......
(groan)
Pretty much a wash.
Doc.... best taken with a pinch of salt........
Southoz
with one before the good Doctor puts his calc away, switches off the neurons
and goes for a well-earned surf.
Southoz.
"Doc" <jfm...@capecod.skipthe.canned.meat.net> wrote in message
news:pXMR4.4625$Up6.9...@news-east.usenetserver.com...
sdbchguy
>
> Tangentiation: There could be a case to quantify the
> horizontal component of kinetic energy from the wave, although
> it probably would be a fraction of the vertical energy.
>
For a deep water wave, the total energy is split equally between
the potential energy (displacements from sea level) and kinetic
energy (motion of water particles).
SDbchguy
Doc
> Thanks Doc, I admire yer enthusiasm for puzzles. Now someone else come up
> with one before the good Doctor puts his calc away, switches off the
neurons
> and goes for a well-earned surf.
> Southoz.
Nah, this one's fun, the dynamics of a breaking wave.... and I tend to
travel with a calculator and a small reference book (the Pocket Ref, by
Thomas J. Glover, Sequoia Publishing, Littleton Colorado, USA. ISBN
1-885071-00-0 ) so that I can play with these things.
And....have you ever seen US TV? Makes these problems even more fun to do.
Doc.....<enter>......
Mountain Man
>Thanks Doc, I admire yer enthusiasm for puzzles.
Doc's a classic.
Key word - enthusiasm .....
Here is a quote about it ....
"There lies, I say, in every human creature what is beautifully
expressed by the word enthusiasm - which is from the Greek en
theos and it means 'a god within', 'possessed by the gods'. It is
this Spirit which we all possess but which few ever awaken. Once
awakened it grows with unbounded fever and it can drive a boy or
a girl or a man or a woman to wondrous things. I have seen it. A
tiny spark can set the world aflame and the light of a single
candle can pierce the darkness."
- Professor Julius Sumner Miller
- http://www.magna.com.au/~prfbrown/wyisitso.html
"Southoz" <sou...@yahoo.com> wrote:
>Thanks Doc, I admire yer enthusiasm for puzzles. Now someone
else come up
>with one before the good Doctor puts his calc away, switches off
the neurons
>and goes for a well-earned surf.
>Southoz.
>
>"Doc" <jfm...@capecod.skipthe.canned.meat.net> wrote in message
>news:pXMR4.4625$Up6.9...@news-east.usenetserver.com...
>>
>> "Southoz" <sou...@yahoo.com> wrote in message
Timothy B. Maddux
flek <flek...@aol.compound> wrote:
[ asked about mass of waves and energy to displace the water ]
What Flek in effect asked about was the gravitational
potential energy of the waveform; if I lift something
up, doing a certain amount of work, it has the 'potential'
to do an equal amount of work in falling back down.
Waves are also moving, so they have kinetic energy.
The total energy of one wave cycle (one wavelength) per
unit width is the sum of the two:
E = rho*g*L*(H^2)/8
In deep water, L=g(T^2)/2pi, so E = rho*(gTH)^2 / 16pi.
The power of the waves per unit with is just P=E/2T
in deep water, or P= rho*T*(gH)^2 / 32pi.
So, for a deep water swell running at 3 ft, 14 s,
the amount of power in a 100-m width is about
1.5 MW.
Doc
"Mountain Man" <prfbrown...@magna.com.au.invalid> wrote in message
> "Southoz" <sou...@yahoo.com> wrote:
> >Thanks Doc, I admire yer enthusiasm for puzzles.
>
>
> Doc's a classic.
The word you are looking for is 'psychotic'...but thanks
> Key word - enthusiasm .....
> Here is a quote about it ....
>
> "There lies, I say, in every human creature what is beautifully
> expressed by the word enthusiasm - which is from the Greek en
> theos and it means 'a god within', 'possessed by the gods'. It is
> this Spirit which we all possess but which few ever awaken. Once
> awakened it grows with unbounded fever and it can drive a boy or
> a girl or a man or a woman to wondrous things. I have seen it. A
> tiny spark can set the world aflame and the light of a single
> candle can pierce the darkness."
>
> - Professor Julius Sumner Miller
> - http://www.magna.com.au/~prfbrown/wyisitso.html
Pete, you're something of an etymologist and a clasical linguist; does the
word 'ethos' come from the same Greek roots?
Doc..... been a long time since my Plato seminar and learning a little Attic
Greek.........................
flek
>Pete, you're something of an etymologist and a clasical linguist;
his wife says he's a 'cunning linguist'....hmmm
Down here, nitrogen narcosis, often called the "rapture of the deep," begins to
affect judgment and movement.
Southoz
Doc trivialised the effect of water temperature on wave power per cubic
metre (we'll be using metric for this ok, adds another step for y'all)
soooo....while I was thinking about hollow powerful waves (which I do all
the time), methinks what else could increase the potential energy of a wave
thus delivering more.. (just more ok).
The inspiration for this one comes from those brown rivermouth barrels I see
on all the US-AS'ers sites, yes thats right 'suspended sediments', there
must be a couple of tonnes of fine silt mixed with the salt and pathogens
out there. I'm not talking about sand, because we all know good surf beaches
have no sand, or very coarse stuff that doesn't suspend well I mean that
good old fine stuff that is usually from rivers. Weigh me up a cold cubic
deci-metre of that gear slapping down on one of Bud's new toothpicks and
lets see what happens.
Coming soon: Barometric Pressure....
Southoz.
"Doc" <jfm...@capecod.skipthe.canned.meat.net> wrote in message
news:QbUR4.1147$vN5....@news-east.usenetserver.com...
>
> "Southoz" <sou...@yahoo.com> wrote in message
> news:8f8bp3$ba...@gamgee.cc.flinders.edu.au...
> > Thanks Doc, I admire yer enthusiasm for puzzles. Now someone else come
up
> > with one before the good Doctor puts his calc away, switches off the
> neurons
> > and goes for a well-earned surf.
> > Southoz.
>
SURFGEO
>on all the US-AS'ers sites, yes thats right 'suspended sediments', there
>must be a couple of tonnes of fine silt mixed with the salt and pathogens
>out there. I'm not talking about sand, because we all know good surf beaches
>have no sand, or very coarse stuff that doesn't suspend well I mean that
>good old fine stuff that is usually from rivers. Weigh me up a cold cubic
>deci-metre of that gear slapping down on one of Bud's new toothpicks and
>lets see what happens.
>
exactly! see this series for absolute proof:
http://www.surfgeo.com/tex16.html
everyone knows that silt is immensley more dense than water, and therefore
texas waves like these are the absolute most powerful waves around. why, these
babies were easily twice as powerful as jersey or hawaii waves even twice the
size.
man, you were right on! finally someone realizes what macho men jb and i are to
surf here!
surfgeo
http://www.surfgeo.com
Doc
> Ok, if you're still keen, I've got another angle on this wave power thing.
> Doc trivialised the effect of water temperature on wave power per cubic
> metre (we'll be using metric for this ok, adds another step for y'all)
> soooo....while I was thinking about hollow powerful waves (which I do all
> the time), methinks what else could increase the potential energy of a
wave
> thus delivering more.. (just more ok).
see
> on all the US-AS'ers sites, yes thats right 'suspended sediments', there
> must be a couple of tonnes of fine silt mixed with the salt and pathogens
> out there. I'm not talking about sand, because we all know good surf
beaches
> have no sand, or very coarse stuff that doesn't suspend well I mean that
> good old fine stuff that is usually from rivers. Weigh me up a cold cubic
> deci-metre of that gear slapping down on one of Bud's new toothpicks and
> lets see what happens.
>
Hmm... I hate to say this, but.....
Given that these swells are generated out in 'clear water' and that they
arrive at the sediment-rich break with a finite and fixed amount of
available energy, it kinda leads me to think that while a wave in much
denser 'water' would have more punch per cubic meter, it'd be scaled down,
though maybe speeded up...a quick think about it doesn't give me any rapid
conclusions about speed. _Sound _ waves tend to travel faster through denser
mediums, but I dunno if this carries over.
Such a wave would likely be cleaner (a crosswind would probably make much
smaller chop), buoyancy and planing area would be much enhanced (4'6"
thruster, anyone?) and you'd need very thin rails....... fins could be a lot
smaller...lots of considerations.
To play with this a little further, has anyone ever surfed the Great Salt
lake (US) or the Dead Sea, where the much higher salt concentration makes
for much denser water?
Doc.....
Mountain Man
...[trim]...
>Pete, you're something of an etymologist and a classical
>linguist; does the word 'ethos' come from the same Greek roots?
Actually I gave up my involvement with insects when my flea
circus escaped over the sand dunes last time I went north
with the last of my surfwax. ;-)
ethos n : character ...
the distinctive spirit of a people or an era; "the Greek ethos"
>Doc..... been a long time since my Plato seminar and learning a
little Attic
>Greek.....................
To tangentiate according to the ethos of the "New Age" (and
I am not really any NewAgeDude), it would appear that there
is emergent evidence to indicate that there exists the
possibility that western civilisation came from a cradle in the
Indus/Sarasvati Valley, in the east.
My notes/references in this area are at:
http://www.magna.com.au/~prfbrown/Indus_Sarasvati.htm
It is rather interesting to mention here Doc that one of the
more higher profile organisations which (of course) support this
"history-flip" is one with the acronym WAVES - World Association
for Vedic Studies.
The review of the old books and philosophers of the planet
would not be complete without stepping outside the traditional
western "roots of civilisation", if only for the exercise of
trying to understand the history, and "ethos", of other cultures.
When it gets flat, or the light is out, and you have the *time*
to spare, boil the kettle and make a cuppa, and settle into
the story part of the following story ....
http://www.magna.com.au/~prfbrown/tasoc_01.html
But if there's surf, get out into it !!
And keep the stoke, no matter what.
Mountain Man
>flek...@aol.compound (flek) wrote:
>his wife says he's a 'cunning linguist'....hmmm
Just watch your ascii around my "surfing widow".
Timothy B. Maddux
Doc <jfm...@capecod.skipthe.canned.meat.net> wrote:
>Density of seawater as a function of temperature. That's
>really the only temperature dependant factor, I'd think.
Not really. The density of fresh water increases by a
mere 4% as it is cooled from boiling to freezing. And,
as Doc noted, salinity effects can often oppose this.
However, the viscosity of the water increases by a factor
of 6. Viscosity is a measure of the resistance a fluid
has to shear; the higher the viscosity of the fluid, the
more shear (i.e., force) it will exert on anything
passing through.
So, cold water is NOT heavier. It is thicker.
--
.-``'. Tim Maddux, Ocean Engineering Lab, UCSB
.` .`~ tbma...@engineering.ucsb.edu
_.-' '._ Santa Barbara Surfing - http://www.me.ucsb.edu/~tbmaddux/
Southoz
I put it forward to the NG for some entertaining discussion, it doesn't mean
I actually support this wild notion. My first opposing argument would be
that if the wave has to lift up that silty brown muck in the first place
before it gets dumped on you, then some there would be some work done
already and the wave would be SMALLER as a result.
bwaahahaha....
oh yeah I think that's what Doc said in this
'...a wave in much denser 'water' would have more punch per cubic meter,
it'd be scaled down,...'
and another thing, those pics of M@rk's are every bit as brown and silty as
yours are.
> man, you were right on! finally someone realizes what macho men jb and i
are to
> surf here!
Yyyyaaaawwwwnnnn!
Southoz.
"SURFGEO" <sur...@aol.comndatube > squealed with joy and wrote
Southoz
explain that oily glassiness that you see in really cold water. Would that
thicker water be more bouyant too ?
Southoz.
"Timothy B. Maddux" <tbma...@wheel.ucsb.edu> wrote in message
> ...
Gleshna
>To play with this a little further, has anyone ever surfed the Great Salt
>lake (US) or the Dead Sea, where the much higher salt concentration makes
>for much denser water?
>
No, but some have surf the Great unsalt Lakes where the water is less dense.
I noticed the lack of floatation so much that I have not given much thought to
the fin. I just use windsurfing large fins, but I had plenty of luck turning
with a small fin on my 12'6" Mistral Superlight.
RichyBob
Timothy B. Maddux
No, as the buoyancy is simply due to the mass of
fluid you displace, and the colder water isn't
any denser (as already discussed). A viscous
syrupy fluid of the same density as water won't
hold you up any more than the water; it may resist
you sinking into it initially, but you will
eventually sink.
--
.-``'. Tim Maddux, Ocean Engineering Lab, UCSB