Its a Good Day

General Discussion
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Its a good day to take a minute (and 54 seconds) to watch this clip (accompanied by Miss Peggy “Is That All There Is?” Lee)Next-Flex.html

The flextails have some interesting characteristics, and maybe a more, well, smarter, person might be able to add their 2¢ as to what’s going on…

The main idea was to have a shorter, thicker and wider board that could be an easy wave catcher and maneuverable and bend a bit to conform to hollower sections.

Originally I thought the tail flex would allow for a straighter exit rocker- for speed- with tail rocker “on demand”: that it would bend in rocker as you loaded up the rail. It does do that, but at the expense of a certain crispness and instant response that you get from a “regular” board. That’s the case mostly off the top, (maybe because you don’t get the same sort of “G” forces, there?), but mid-face or off the bottom you actually have to be pretty easy with your weighting, because it really wants to jump out of the turn.

All in all, they seem to work best with a relaxed, easy approach, where you just let them find their way.

Here’s what I notice riding them: The pluses: In hollow and/or lined up waves they’re gearless, meaning that they go fast, without any staging or shifts, and, for short, wide boards, they don’t cavitate or get skittery (one of these days I’ll get back to Indo and see how much I can wind them out). They go fast (did I already say that?). Landing onto the flats is much smoother than with a rigid board (like having a suspension). Because the plane of the tail area is flexing independently from the entry plane, its not feeding back (think how boogie boarders, body surfers and mat riders conform to the wave face). That tail plane also gets a bit of suction to the wave face (laminar flow) and can ride very high and tight.

Which brings me to the negatives: Because of the above effects, the tails tend to stay glued to the water, and so the boards don’t like to “snap”, there’s a bit of turbo-lag, so its more of a drivey-carvey kind of turn.

But the thing that I can’t quite get my head around is something that I think might be some variation of the “Coandå Effect”: when the board’s in trim, in a laminar-flow state, the water pressure across the bottom actually will suck down a negative, reverse-camber, tail rocker. Its something that I’ve felt, while riding, and I’ve witnessed it with other riders: its like the board’s riding a cylindrical section of water, rather than a flat or concave one. The tail lifts and the nose drops and the board’s feels like its being drawn forward, rather than sliding downhill. It feels really cool when it kicks in- its like you’re draped over a ball of energy. The downside relates to the negative, above, in that it limits its run-out speed, somewhat. Once it hugs that ball, it doesn’t want to let go.

Anyway, maybe its just another way to waste time!

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Hi Allan,

Its a good day indeed…I sussed the video.

How much effort are you applying there when tweaking those tails? The positives sound just like what I’d expect, but if the tails are really easy and rubbery to tweak, theres your answer to the non-snappy feeling you describe.

I tend to think of a progressive flex from nose to tail, increasing in the tail according to whats desirable considering wave power. I.e- not bone stiff through the middle then a floppy bit off the end.

Josh

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Quote:

But the thing that I can’t quite get my head around is something that I think might be some variation of the “Coandå Effect”: when the board’s in trim, in a laminar-flow state, the water pressure across the bottom actually will suck down a negative, reverse-camber, tail rocker. Its something that I’ve felt, while riding, and I’ve witnessed it with other riders: its like the board’s riding a cylindrical section of water, rather than a flat or concave one. The tail lifts and the nose drops and the board’s feels like its being drawn forward, rather than sliding downhill. It feels really cool when it kicks in- its like you’re draped over a ball of energy. The downside relates to the negative, above, in that it limits its run-out speed, somewhat. Once it hugs that ball, it doesn’t want to let go.

Sounds curiously similar to the riding characteristics of another type of flexible surfcraft…

High performance surfmats.

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Thanks for checking out the clip, Josh.

The tails in the clip are the softest that I’ve done, and they’re still fairly stiff, and they’ll “twang” if I snap them.

I’ve done some very stiff ones that were almost too explosive feeling for me, so I dialled them down a bit.

The front half of the boards are pretty stiff to minimize deflection of the entry rocker, and then they get progressively flexier.

I’m not sure if its exactly an “all-around board” solution, but its an interesting diversion.

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Quote:
Quote:

Sounds curiously similar to the riding characteristics of another type of flexible surfcraft…

High performance surfmats.

Right you are. When I started playing with this, a friend loaned me a limp air matress and a pair of flippers so as to get a feel for a what a fully-conformable surfcraft is like. And I’ve watched a few Greenough mat riding clips on youtube (in fact, I remember watching the man himself streaking across some big chunky, stormy Rincon Rivermouth walls, back in the day).

I’ve always been fascinated by other kinds of surfcraft.

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What would happen if you made your flextails like a bicycle shoe, where it flexes in one direction, but is stiff in the other?

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Thats it Etmo,

I’ve done some, mine are parabolic Balsa rails, with the tail rocker after the fins getting flatter, and that means they won’t go too far into reverse rocker. I don’t feel what Allan describes as a sucking down onto the face, but I get the carvy thing…the tail conforms to the pocket in turns and just won’t drift as easily.

Allan, its a diversion I love to get on!

Josh

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Quote:
What would happen if you made your flextails like a bicycle shoe, where it flexes in one direction, but is stiff in the other?

A flex-limiter? The only thing is its the full range that makes the boards fun to ride- the rocker flexing in and thereverse “porpoising” effect. But its definitely something to think about. Maybe some kind of stay, (like a collar stay or in a sail), that inserts, different stiffnesses.

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I’ve ridden flextails and flexspoons off and on since the late 60’s and have experienced the exact same performance characteristics you have. Mine were all single fins. Three standups and a number of flexspoon kneeboards.

As you noted, the flex really comes into play when you put the board into an accelerating turn (bottom or mid-face turn). While I’m sure there is some level of rebound I think what you are feeling mostly is improved water flow over the bottom rather than return of the loaded flex panel (the “baawang phenomenon”). In other words, if you eliminate the drag of a static bottom during a turn it will feel like you are getting a push or rebound.

In a decelerating turn (pivot or “snap”), you need the tail to release so that it can pivot quickly around the rail fin. A flex tail will be all twisted, up gripping the water (like you surmised) and delaying the turn. If you try a bank off the top rather than a snap, you’ll get that same feeling of acceleration you get on a bottom turn.

I had always thought that mixing a multi-fin set ups with a flex tail would allow you to snap a bit better because the fins are so close to the rail…guess not.

I never felt the negative camber thing on my fiberglass boards. I can feel it on the mat and the old-style soft boogie boards. Kinda like a hydaulic jump. You’re just lying there (more on a flattish trim than on a rail) and suddenly…“there it is!” Like someone is picking you up and throwing you down the line. Glad to hear someone else felt it!

Great experiment! I know the hassle it is to make the buggahs! Those are the kinds of board you want to keep in the attic and bring out on those special, glassy, down-the-line days.

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Thanks for the feedback, Lee.

I’ve done some thrusters where the trailer fin actually flexes with the panel. That’s a lot going on back there, for sure!

If its a hook-y turn off the top- off the lip, they work great, because, like you said, its an accelerating turn, and the boards feel very fluid yet positive. The only drawback (literally?) is when coming out onto the flats with speed, and wanting to slice it around. In that case the tails seem to want to stay sucked down and track a bit. If you actually step over the flex panel you can counteract it with your foot and weight, and blast it around.

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really cool stuff man! i made a couple multi fin spoons a couple years ago and your ‘reverse rocker porpoising’ phrase really rang true in my head on the second one…it was this carbon 5-5 quad edgeboard piece of crap that warped from the pour foam and had like 3/4" of reverse rocker in the last foot out the tail…about 8-10 layers of 4 oz carbon tail thickness if i recall (as thin as 4-6 layers in entry lam in nose that you could lay your hand on and feel ripple as you went down the line)and VERY stiff rails. I think the reverse tail rocker worked as a preload that made critical take offs horrible (but man prone and kicking like a giant handboard you could fly in sooo early on that diagonal point energy unbroken wall to backdoor the main stuff like at con indicator etc) but it was flexy enough to do tight roundhouses once up and riding, even on small waves (it had SUPER flexy paddle lead fins that u could break free etc). if you could get goin doin roller coasters on a decent shoulder high point wave the down drive acceleration off the top (like a accelerant line maybe 15 degrees down the face, mostly down the line from as far up as u could pump to without airdropping while coming back down)was insane feeling, unlike any thing i’ve felt in that specific circumstance, in fact I have decribed it before as like a dolphin’s tail bending to arc u up the face when grabbing rail and pulling off bottom, then totally reversing past neutral into its reverse mutant rocker to drive u down the line when shifting your weight forward and downward off the top, board could not ride juicy reefiness at all tho, would run like mad from barrel, you had to lean so far back and pull so hard on outer rail not to outrun it…hard to control

sorry for the self absorbed rant but your experiments are awesome and reminded me of the experience i really like you oneula’s and ambrose posts man take care

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This is a GOOD thread. I have thought this would be the case to greater and lesser degrees, but your actual work in the field and understanding of the Coanda effect in the tail. Impart! Impart!

http://www.swaylocks.com/forum/gforum.cgi?do=search_results&search_forum=all&search_fields=sb&search_type=AND&search_string=coanda

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The potential for Coanda induced acceleration in flex-tail boards is interesting. We get reports from our riders

of ‘‘the board picking up speed in unusal places on the wave’’, as one guy put it. I’ve been looking for the cause

of that, and it ties in perfectly to what’s on this thread. How we test or prove this theory is beyond me, but it sounds

like fun trying.

I really like the looks of that fishy, Allan. Kick all the longboarders out of the cove at low tide and that thing would be fun.

Mike

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ENGINEERED FLEX - The Next Frontier

Surflight boards use technologies that have roots in surfing, snowboarding and bodyboards.

What you see and feel in a Surflight board, the outer portion of our boards, is made with a flexible foam, similar to bodyboard foam. Like a conventional hard surfboard, the foam is custom hand shaped. It is then coated with a smooth and extremely tough urethane finish.

The heart of our technology is a composite structure inner core surrounded by the flexible foam. Imagine a snowboard (itself a highly sophisticated composite structure) within a flexible foam surfboard. Like a snowboard, the Surflight inner core is made of a composite of epoxy resins, an exotic stiff foam and carbon and fiberglass cloths formed under high pressure and cured with heat for high strength and light weight. The inner core is contoured to give the right amount of flex and spring, and like a snowboard, it acts as a “torsion box” to eliminate twist. The core functions as a “composite structure” because the pressurized forming of the materials causes them to function as one melded structure, much like modern snowboards, skis and tennis rackets.

This is copy from Surflight one day i will get another so many things going on out there Jim Richardson has got it right maybe someone can get him to post his thoughts go have a look at his site boards like his at point breaks where they can be wound up would be magical.his boards are not conventional so people want what looks familiar but he is a few years ahead of others in flex theories aloha…