Speed Surfing challenge

General Discussion
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Quote:

Mike Paler has expressed concern about the ‘tiffs’ which are happening in discussions involving myself. Anyone who wishes to contact me should do so on my e mail as I will not be entering into discussions on this public forum.

…I’m Sorry…did I break your concentration?

…No…then let me retart…should I stay? or should I go?

DANGER+OPPORTUNITY=CRISIS tm.

Herb

202

GO!

oh yeah,

my wife watched me surfing a couple of days ago and said i was going 5 times faster than everyone else…good enough for me…i’m guessing 40 to 45 mph…

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The fastest surfer I have ever seen is a Gannet. The Gannet rides the air above the wave, so is not surfing in the traditional sense. Nevertheless the gannet uses the energy of the wave to gain speed via aerodynamic lift. I imagine that the greatest opportunities for high speed surfing runs will occur in conditions where there is a strong offshore breeze blowing, using boards which are designed to gain aerodynamic lift. Some part of the board would have to be in contact with the wave for the ride to count as surfing rather than flying.

The best posture that the surfer can adopt at high speed is prone, as this position minimises drag. Windsurfers are discovering that drag from the air passing over the body of the rider is limiting the top speeds which can be achieved. Surfers do not have to stand up to hold a rig, and are thus able to avoid this source of drag.

Regards, Roy

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as i recall, there were a few gannets out that day…some kestrels and kites, also…i smoked 'em all…

just ask my wife, she saw the whole thing…

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Surfing as fast as a gannet must surely be a blast. Just as in skiing or ice skating there are those who like to do tricks, and those who like to go fast there are those in surfing who like to do tricks, and those who like to go fast. We don’t even have a clue what speeds are really possible in the future, but I am keen to find out.

206

Should he stay or should he go?

Will he take it or will he blow?

So far the results are mixed but encouraging.

Happy BDay Cheyne!

207

Hey, Roy, pleased to see that your period of penance in the penalty box is up. Heresy must have its sanction. Accuracy is irrelevant. You seem to have made a near-subtle shift in parameter.

Chuckles.

208

hey Roy Stewart

I only read 4 or 5 pages so you might have answered this but I was wondering- where do you surf?

and what does your surfboard look like?

Last winter I was driving by the coast durring a 20@20 day and noticed a surfboard would have to be able to go over 35 mph to make the wave

no one was out

209

Hello Daily,

These days I usually just surf beachbreaks in the Bay of Plenty, New Zealand. You are welcome to check out various boards of mine at http://www.woodensurfboardbuilder.com Unfortunately the site is plagued by pop up advertising windows from ‘cool page’ but they click away ok. What is a 20 @ 20 day? Does that mean 20 feet with 20 knots offshore?

Roy

210

hi Roy

I tried to check your boards

you are right about the ads

I ment 20 feet plumline at 20 seconds with 20 knot offshores

I live in northern california

your posts and pictures make me smile

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“The best posture that the surfer can adopt at high speed is prone, as this position minimises drag”

Hiya Roy,

Then will your boards go even faster if you were to ride them prone? Do you sometimes surf laying down? Do you think prone is the future for high speed surfing?

Thank you in advance.

212

Hello Hootingtubes,

The prone position would be the fastest when the rider faces a stiff offshore or sideshore headwind and is trying to reduce friction and make the shape of the vehicle more aerodynamically efficient. In cases where there is a tail wind or no wind the rider might be better to stand up and pump the board.

I find it interesting to imagine extreme cases. I don’t presently surf laying down, I am more of a ‘campfire squat’ type but will give lying down a go when I get my Paipo built. There’s a guy in Raglan known as ‘Daffy’ who regularly rides tubes on the ledge using the coffin position on his longboard (lying on his back).

It takes all types to make a world!

Roy

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Roy,

Will your paipo be finless, have a tunnel fin… or?

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Hi Dale, It will have a tunnel (no front fin, sideslip city at low speeds)

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Today I tried to see a video clip of Laird Hamilton towing in at Maui (via surfermag.com) but my dial up only got me a black screen with a soundtrack. The soundtrack was interesting as it said that Laird was doing 50mph, I wonder how they record that?

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"I wonder how they record that? "

The ski’s have speedometers and their maximum hull speed is about 50 mph. Laird is goin 50+ as he “whips” into the wave. The ski keeps up with him through most of the drop, hence the estimate of 50 mph.

There was a guy at Scripps Institue of Oceanography named Kendricks or Hendricks back in the 70’s who built instrumented kneeboards to evaluate board speed vs absolute speed (based on movies taken from a pier). One of his conclusions was that the fastest a surfboard (board speed) could go was on a drop. As soon as you turned or angled away from the steepest part of the face, you slowed down. (there is a slight delay in slowing as puting the board on edge reduces the wetted surface) I think this has also been proven using radar guns…

He was pretty sure that the “feeling” of speed on a trim or “boogieing” (as pumping was called in those days) is just that; a feeling or optical illusion. If gravity is the main force propelling you on a wave, any variation from the steepest line is going to slow you down. Also the longer you “fall” (the bigger the wave you are dropping into) the faster you will go until you reach the terminal velocity of the hull or plane you are riding. The reason Laird can go 50 mph while everyone else is going 15-20 is that he starts out at 50 mph, drops down a huge face, and rides a small vehicle with less wetted surface (less drag).

I personally think that the thruster fin setup or modern bottom contours may allow the rider to temporarily increase board speed but by in large you are stuck going (9m/sec/sec X the sine of the angle of the wave face X the time it takes you to drop in) - (hull friction+wind resistance)…

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Quote:

"I wonder how they record that? "

There was a guy at Scripps Institue of Oceanography named Kendricks or Hendricks back in the 70’s who built instrumented kneeboards to evaluate board speed vs absolute speed (based on movies taken from a pier). One of his conclusions was that the fastest a surfboard (board speed) could go was on a drop. As soon as you turned or angled away from the steepest part of the face, you slowed down. (there is a slight delay in slowing as puting the board on edge reduces the wetted surface) I think this has also been proven using radar guns…

Terry Hendricks is a contributor to this forum and has contributed to this thread. Although some of what you are recalling is not current (60’s) as more recent observations have indeed shown surfers in some fast wave situations going faster than the energy solely provided by gravity and face height. But by and by its generally true.

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Dear Lee,

Thankyou for your reply.

The formula 9.8m/sec/sec X the sine of the angle of the wave face X time neatly expresses the fact that an angle of descent which deviates from the vertical will result in a lower rate of acceleration than that which is experienced in a vertical descent. The formula can thus be used to calculate the rate of acceleration of an object at different angles of descent. Clearly a path which was at ninety degrees to the vertical would result in a zero rate of acceleration, while a vertical path will result in an acceleration of 9.8m/sec/sec. All other paths will result in a rate of acceleration which is greater than zero and less than 9.8m/sec/sec (excluding friction).

You state that a falling object (eg a surfer and surfboard) will slow down as soon as it enters a path which deviates from the vertical. This is not the case. In fact, what will happen when a surfer and board enter a path which deviates from the vertical, is that their rate of acceleration will decrease. Thus, given that a rate of acceleration still exists (which it will, provided that the path is not at 90 degrees to the vertical and excluding friction) then the speed of the surfer will continue to increase, but at a slower rate.

To express the situation using an extreme case, imagine a surfing situation without friction. In such a case, any rate of descent (or glide path angle below the horizontal) will result in a positive rate of acceleration. No matter how small this rate of acceleration is, given sufficient time (and a frictionless path) the speed of light will be approached. This is the case no matter how small the wave, or how slowly it progresses towards the beach , provided that the wave moves toward the beach ( because beachward movement of the wave is needed to replace the gravitational energy lost during descent).

Thus it can be seen that the only impediments to surfing speeds which approach 186,000 miles per second are

  1. Friction, and

  2. The length of the wave (which represents time in the formula)

In real surfing situations, for any given wave, the maximum speed will be achieved by the board which has the least friction, and unless the wave is unusually tall and unusually short, that maximum speed will be achieved by angling across the wave face in a path which deviates from the vertical.

Furthermore it has not yet been proven what fin setup (if any), length of board, width of board, weight of board, or shape of board constitute the fastest setup in any given surfing situation, although opinions and personal preferences abound in this respect.

I should also add that the statement that ‘everyone else’ (except for Laird Hamilton) goes 15 to 20mph is not accurate. James Sowell was clocked via gps at 23 mph on one of Dale’s mats

Yours Faithfully, Roy Stewart

PS There are two other means of accelerating the board which can only be used in a path which deviates from the vertical, namely 1) a pumping action from the rider, and 2) lift from offshore air flow.

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“I should also add that the statement that ‘everyone else’ (except for Laird Hamilton) goes 15 to 20mph is not accurate. James Sowell was clocked via gps at 23 mph on one of Dale’s mats”

When I receive word from mat surfing friends in NSW that the tops of 6’ to 8’waves are being torn off for nearly 100 feet on a single high arc… I have to wonder just how fast…

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I still think this is all far too relative and subjective for much of a definitive analysis. Surfers get such short burst of speed while dropping, and slowing while climbing, that it’s relative to the surf, the surfer, and the boards. If everyone used the same boards it would come down to the surfer; if different boards were used than it comes down to the waves more.

I don’t see how anyone could go faster than the big tow surfers on those little boards. Seeing “Riding Giants” the other day, there was some video shot from the water on faces over 40’. Oh my god, they were going light speed, multitudes faster than Roy on his Timber. I’d say, in the shot of Dave Kalama, he was going over 40mph, no pan, normal speed. There was no need to exaggerate anything.

Fast is Fast is fun…leave it at that.