Discussing Roy's surfboard designs.

[Roy Stuart]

No, actually you have no concept of physics. There are multiple forces from the wave, and the speed of the wave is important for surfing speed.

http://www.rodndtube.com/surf/info/i...10N3-69-07.pdf

But I am sure you know more than someone with a PhD in physics.

I know Terry quite well, and have read that paper before. There's nothing there regarding the forces which drive board and rider which contradicts what I've said, and in fact the issue is not directly addressed there at all.

When you refer to the 'speed of the wave' I assume that you are referring to the speed of the wave front towards the shore. Of course this speed affects the speed potential of board and rider, for the simple reason that increasing the speed also increases the rate at which the wave lifts ( all else being equal). This increases the rate at which the board and rider can acquire gravitationalpotential energy, and this allows board and rider to convert the potential energy into kinetic energy at a faster sustainable rate. This leads to greater speed ( again, all else being equal).

The interaction between the surfboard and the water ( hydrodynamic forces) create necessary lift and allows control of the direction and trim angle of the board (and thus also the fall line as well) all of which is required for the acquiring and conversion of gravitational potential energy into kinetic energy. Hydrodynamic forces are also created via muscular input from the rider, these can be used to propel the board also.

Please address your comments to the subject matter, without making spurious and illogical ad hominem and 'from authority' arguments. The argument from authority is particularly hopeless when it misinterprets what the information from the source actually implies.. as you have done.

[Roy Stuart]

I disagree with this last statement completely. Typical modern surfboards move fastest on the face of the wave where the water is moving the fastest...

That is true of all surfboards, and it is not only compatible with what i have said so far but is a necessary condition for it.

The reason why surfboards can move fastest in the part of the wave where the water is moving the fastest is due to the fact that the water lifts board and rider there, in addition the steeper slope allows reduction of wetted surface area.

and they do so because they are able to tap into that kinetic energy

That is correct.. and that kinetic energy is primarily a lifting force, which is transferred into gravitational potential energy and back into kinetic energy, this time of board and rider.





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[Roy Stuart]

In the videos you have posted of you surfing, I can see that you do gain a decent amount of speed and the added weight of the board actually looks like it helps to keep that momentum. Have you ever considered linking up with a surf shop on the east coast and maybe having a board there that people could demo, maybe pay like the cost of a board rental for a day, so that some of us could try it out...'cause i highly doubt any of us can afford one.

Here is the website for one of the local shops around here, they would probably be more than happy to store and demo your board...http://www.chaunceyssurfshop.com/Tweets.htm

There's a 13 foot 'Ghost' model in San Francisco at present which is bound to make its way to the East Coast, it's a good all round board which isn't as fast as the 12-9 tunnel finned board in the latest video but still has a good turn of speed.

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[LBCrew]

Here is my own gross oversimplification...

Wind pushes laterally across the beam of a sailboat. The sails catch the wind, which applies a lateral force upon the boat. The mast transfers that force to the keel and hull, which pushes laterally against the water. The water pushes back on the keel with an unbalanced but opposite force. The result is forward motion.

Water is the medium under a surfboard. The water moving up the face and toward the beach applies a lateral force against the fins and hull. Gravity pulls the rider down, applying an opposite but unbalanced force back against the fins and hull. The result is forward motion. And that's where your theory stops.

I would continue, suggesting that modern surfboards surfed rail-to-rail can gain speed by turning, because turning requires rider input of energy into the system, which is used to change the angles of attack of the fins and bottom, tapping into the energy of the moving water within the wave. This applies in small waves moreso than large waves, when the wave supplies plenty of energy for speed. It also applies only to certain kinds of turns... not all turns... dependent upon a number of factors including fin foil, radius of turn, and bottom contours. Just as a sailboat can sail against the wind, surfboards can increase speed by adding wave energy to gravitational potential energy. This can only happen at certain angles of attack, not reached on your boards, and is more effective when the board/rider mass is reduced. This means modern shortboards may not have the momentum of your boards, and can't drive through sections like yours, but they can accelerate briefly.... attaining shortlived bursts of speed... through turning.

It might attribute to what shortboarders refer to as "squirt?"

[brewengineer]

Done arguing with the person that can't admit when he is wrong.

[bubonicphoniks]

Roy, that's too much money to ask for for a surf board. It is insulting that you even post those ridiculous prices and I am appalled. Forgive me for not reading through the entire thread but what exactly would one get for that sum of money, what makes the boards so expensive, and how many have you sold?

[MFitz73]

Roy, that's too much money to ask for for a surf board. It is insulting that you even post those ridiculous prices and I am appalled. Forgive me for not reading through the entire thread but what exactly would one get for that sum of money, what makes the boards so expensive, and how many have you sold?

He's not going to tell you. I also would like to know what material or design element or fabrication methods require the price to be so High.

[Manisses]

Halftime. Here is your sponsored ad. When we return, huundreds of more posts about this mystical man and his half surf half art..... things (that are worth 3.5 billion each, or some other such ridiculous figure).

[yankee]

He's a loon.

This thread may never die.

[Willis55]

I mean with a few hand tools and a garage i could replicate what your doing. You cant charge hundreds of thousands of dollars for something i can make myself. Lets take cars for example. I cannot build a Ferrari in my garage. A Mclaren F1 is a million dollar car. Space age technology at your fingertips, 0-60 faster than you can blink, and the ***** you would get in the car is unreal. Thats what a millionaire wants for a million bucks, not a peice of wood that does nothing. This guy cant grasp the concept. Hes going to use fancy words to make it seem like his boards are groundbreaking. His boards are super fast though? The next time i get challenged to a surf race ill think of gool ol' roy