Anyone? My most recent build, has a matte finish main fin, with a ‘‘SharkSkin’’ texture on a slender pre-fin. A technique for increasing hydrodynamic efficiency of the fins. With a resulting increase in the performance of the surfboard. Just curious if any of you had also gone down this path. Counter intuitive, though it may be.
Bill
i dunno bill…anymore i’m spoiled/addicted to the secret fin…regular fins pale in performance.
herb
Bill are you saying your “pre fin” is in-line with the main fin? I think Wildy did a bunch of those…as for playing with texture, not sure. Its an unusual combination of things to do. are you trying to trip a boundary layer, or? I don’t think it’s counterintuitive, necessarily.
Keith, yes, they are in line. The pre-fin is the approximate size and shape of a Saber Tooth Tiger’s fang. Both fins are mounted in the same box. The function is very much like a small canard, or slotted leading edge on an aircraft wing. The purpose is preventing the MAIN FIN from stalling at a high AoA, when making an abrupt turn.
Bill
…hello, I do not know how exactly is that Shark skin, but I made boards with in line config all in HPSB. I rode myself one for 3 years or so in mid ´90s.
All speed finished.
Here s one used in Indonesia by a customer that have 12 Hawaii seasons and around 10 Indo ones.
Bill, personally I am not old enough to have seen a saber toothed tiger in person. Could you tell me more about it?
I’m guessing the texture is to increase laminar flow and reduce turbulence, thus reducing cavitation?
This makes me curious about laminating a fin (or the bottom of a board!) with ACTUAL shark skin!
I surf my keeled fish that you treated on Sunday, Bill. I can’t say I noticed a difference compared to the non treated fins. I wonder if we’re reducing friction why not do the whole bottom? Is it cost prohibitive? Mike
You actually go faster by increasing friction. (Are you messin’ with me, Rooster?)
Bill
Is that anything like Herb’s MVG fins? I have a mini vortex generator fin in front of the center fin on a thruster but have not been able to determine if it’s faster. If it gives me 5% more speed, it’s worth it.
No, totally different.
No Bill, I’m not messing with you. I kind of get the theory or idea that increasing friction creates a boundary layer,or water flowing over water. I think of that as reducing friction. The contrary idea of increasing friction to reduce friction. Perhaps I’m visualizing it incorrectly. But, what I’m wondering is why stop with the fins and just do the whole bottom. Rails, too. Is it cost prohibitive? Pain in the ass to do? Just a sincere, not bullshit’n yah,just wondering question. At my age I’m looking for a little edge staying on a smaller platform. Sunday’s surf I was feeling my age and I have definately had better surfs on that board with the treated fins. Maybe too much beer that weekend after going on a little pig hunt. Mike
Aloha Rooster,
No, it’s not cost prohibitive. Just wrong for the bottom of a surfboard. A surfboard operates at the air/water boundry layer, moving OVER the water. While a fin is moving THROUGH the water. The textured surface is appropriate for the fin, and a highly polished/waxed surface is what you want on the bottom of a surfboard. I know, I know, someone will bring up sanded boat hulls, but remember, a boats’ hull is moving THROUGH the water. The texture on a fin increases the surface area of the fin allowing the fin to tap into (extract) more of the kinetic energy of the wave. Thus, making it possible for you go faster on the wave.
Bill
Thanks Bill.
Bumping up because: Mr. Stoneburner made referance to this older thread, in a current one. Thank you, Mr, Stoneburner.
You know me I usually have everything and anything contrarian
I still have those sets you caoted for me and several sets of the 3-D fins
I also did that whole bottom texture experiment back in the early 70’s
back then there a was theory that if you used the bottom design of a balleen(?) whale you could direct the flow using hundred of micro channels going front to back so a guy made a super thin 1/16"-1/8" rubber mat that stuck to the bottom of your board to make it go faster. Of course you know me, I boughtit and had to try it out. No difference than when I tried Morey’s ideas of waxing the bottom with a couple bars of irishspring soap or a light coat of resin with bottles of crushed alkaseltzer on the bottom then paddling it out and sanding it to expose the alkaseltzer to get a poppop fizzfizz reaction before you caught a wave.
Needless to say the guys in the line up hated me back then
they thought I was crazy,
I think they used to call me the mad professor
But it was fun experimenting with all kind of craziness back then
tried the inline putting a finger trailer in the box before a main fin
didn’t notice too much
tried those periscope fins with wings, rainbow s-drives, and other fins with a wing at the tip as well the c-drive design
just ordered these new fins with a lip above the base
(Six of one, half-dozen of the other.)
Actually, I referenced your thread of this title from 4 years ago,
“The Counterintuitive Concept of…”
in your recent thread of this title,
“Increase Drag, for a NET GAIN in SPEED.”
Almost referenced another from 6 years ago too — redundant.
Yes, redundant. Also accurate, and true.
Pb + magic dust = Au
