The Counterintuitive Concept of...................

Increasing  the drag on you fin, to make the board go faster.      Think about it, before you say nay.     It happens at the molecular level of water, in a wave, as it impinges on your fin or fins.

Interesting to think about. No fin equals no drag and no speed. Big fin equals lots of drag and no speed. Balance is somewhere in between.

    If true, that makes it very difficult to explain the Hot Curl boards.

Most of board design is simply opinion. It’s very hard to quantify design principles in a scientific manner. I guess you could test his theory in some kind of flowing water tank, but it would be exceptionally difficult to accurately model the actual dynamics involved in surfing. 

That said those that have ridden finless boards are often of the opinion that they are rather fast. 

I was waiting for someone to mention a finless board or an aliea. In my thinking, something along those lines, because of the thinness of the board, the entire board is a fin. What I mean is a thin aliea is closer to riding a fin without a board attached. If that makes sense.

But yes I agree that certain craft are very fast without a fin. Just not a standard bouyant surfboard.

Increasing the drag on you fin, to make the board go faster

 

Its not the drag that makes it go faster >< . You wont increase the speed of the board by hacking the fin with a knife.

 

Most of board design is simply opinion

 True dat. Explains the widespread idea/misinformation of the surfboard acting like a spring. When you deform the surfboard by pushing your hardest, you`re not compressing a spring, you are crumbling a sheet of paper.

When I put a 10" dolphin in my longboard it reaches warp speed. A 7" greenough is a little slower, but because it turns so much better, I can generate lots of speed through turns. 

Increasing the drag or friction on the fin increases the energy or force transfered from the rising water in the wave face to the fin. The same increase comes from making the fin larger. So a small textured fin could have similar properties as a large smooth fin.

Am I close Bill?

   More than warm, but a little shy of hot.   Still worthy of BINGO !

If you windsurf, you know the answer. The wave is replacing the sail.

Most everything current in surfing and suping was stolen from 20 year old windsurfing tech and understanding to include nylon,cork,cf,wood,stringerless,flex tails, quads, doubles, skinny,wide,flat, complex, chines, <1lb eps, high density foam, no nose, full nose, light, strong, automotive paint finish.

 

No malice Bill and fellows

But does

“Increasing  the drag on you fin, to make the board go faster.      Think about it, before you say nay.     It happens at the molecular level of water, in a wave, as it impinges on your fin or fins.”

Mean 4 fins are faster? (HA)

A few suggest that the absence of a fin is why the aliea, hot curl and also the olo go so quick.

Speed is relative here!

These (ancient) rockers IMO are the key to speed.

Since balsa’s, we have increased what the ancients spent, well a hell of a lot longer refining

compared to our tom foolery!

 

Big fin more drive faster board.

Don’t bet on it.

The problem with physics and surfing is that 90% of the time, the physics are interpreted incorrectly.

Drag is by definition the force that is opposed to the direction of travelling. So drag will always slow down your board, unless if Newtonian physics do not apply on surfers or if you change it’s definition.

And drive is not a term used anywhere in hydrodynamics, it’s something invented by surfers. (https://www.google.be/?gws_rd=ssl#q=drive+hydrodynamics)

Edit: I found one definition for hydrodynamic drive, but it’s nothing like what surfers use it for: http://www.answers.com/Q/What_is_Hydrodynamic_Drive

It is a relief to know that the laws of physics have not changed.

I believe what is referred to as “drive” is the perception of the centripetal/centrfugal acceleration experienced from cutbacks and turns.  More physics.

It is a relief to know that the laws of physics have not changed.

I believe what is referred to as “drive” is the perception of the centripetal/centrfugal acceleration experienced from cutbacks and turns.  More physics.

     Psssssttt, (in a whisper) the wave is replacing the wind.

For general reference:

Force = Mass x Acceleration

&

Centripetal/Centrifugal Acceleration is

a = \frac{v^2}{r} \, ,  where a = acceleration, v = velocity and r = radius

the more the water sticks to the fin at a molecular level

the more the fin “dissappears” in relationship to the waterflow

allowing the fin to achieve laminar flow versus creating cavitation

cavitation or the disruption of the interaction between the surface and waterfow

creates flow disruption, inserts air and creates turbulence… hence drag

cavitation is the enemy of all watercraft because it creates loss of direction and loss of power

you can over power it and push the cavitation away from the surface area with gas turbine engines or water jet propulsion or just be a porpoise/shark (99% muscle power)

in an ideal situation you don’t want to see any bubbles coming off a surface as water flows by

if the micro bubbles stay on the surface that’s fine but if they break off and create a trail of disrupted waterflow then you have drag

sometimes drag is good for control

but if you stick your hands in aerated water you’ll notice there’s no “stickiness” just chaos

that’s why 6-channels go bonkers when a mass of white water gets caught underneath them

there’s nothing to grab to establish direction

sorry if this doesn’t make sense

at least that’s my layman’s understanding of that white sh*t that comes off fins

that’s why I like Griffin’s and most old tiimer shaper’s vision of building in “release”

the sooner/faster you can get the water off the surface that less chance you have of creating bubbles on or from the surface

they do it through design

others are trying chemicals like nano coatings or surface texturing