Can anyone explain "scoop rocker" and "spiral vee" for me please?

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Spiral vee is old surf term for vee increasing towards tail. If U look at it from the tail upside down on the shaping stands, and drag a straight edge toward you the straight edge drops with rocker and horizontal angle increases with vee so it appears to 'spiral' which may be the origin of the term when that guy whatsisname invented in the 60s or 70s

Anyway we don't do that in windsurfing anymore - quite the opposite

As the same guys who invented spiral vee long ago also did double concave some people believe that it just means vee with double concave in tail but that's not corrext. Possibly why starboard claimed spiral vee in the EVO boards? I dunno as I haven't seen an Evo for ages but I do know that no modern windsurf board I've seen has increasing vee toward tail

I thought spiral V is created in the tail from parallel concaves running along the board . As the tail gets narrower deleting the outer concave leaving the centre concave creating more V . Which creates more tail rocker on the sides . My rough water board has this and is a smooth ride .
Scoop rocker = front rocker ???

I had an Acid that had spiral V I thought it worked quite well

What about "scoop rocker"? Is this just a marketer's way of saying "rocker - this board has some"?

Scoop and nose rocker seem to be interchangeable in the old vernacular so I dont think scoop rocker is a thing. Confusing it further is some surfboards have a deck scoop - or refer to single concave nose riders as scoop in the same sentence as rocker so good luck

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Haggar said..
I had an Acid that had spiral V I thought it worked quite well

That's same as Evo
I dont know that they actually had increasing vee in tail as it's so awful
I'd love anyone who has them to measure

IMAX what board?

I have seen on a video Patrik saying he uses a "scoop rocker line", I thought it was referring to a continuous rocker but the board in question definitely has a flat section.

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Mark _australia

IMAX what board?

A board I made , still ride it and love it .
It has parallel double concaves , ( 5 mm) , all the way down the board . Created with a curved sanding block , so the cocave curve is the same all the way back .The blank started with 10 mm V at the front to no V at the back. 2 mm tail rocker . It has a rounded pintail . Once the concaves are in , it effectively created 5 mm V at the back with 4mm rocker at the sides , measured at front of fin box, 2 mm rocker in the middle . I made it for rough water in Port Phillip Bay . Now that I'm in QLD and sail flatter water it only comes out on rough days . Oddly though , it's the board I've had my fastest times on . I put that down to the conditions rather than the board.
I believe ? , the Severn FOX has similar dimensions . It , I once read , was designed in Port Phillip Bay and eats chop.
Flicking through a recent windsurf mag they were testing 10 crossover boards . Half had double cocaves the length of the board with pronounced V. I think it's a returning trend .
No mention of spiral V.

I have spiral V on my Fusion FSW boards. The V angle increases from 400 off to the tail and again increases forward from 900 off. It works great.... eats chop.

Im amazed at what another couple mm of V or double concaves does to the ride of a board .

It's amazing how a 10th of a micrometre can throw out the vee convex shape of a boards water displacement design. Do windsurf board shapers, still use Skil 100 planers or is it high-tech now.

And... what the heck is "inverse vee"?

As in how would you interpret this www.fmxracing.com/veloce-ltd-116/
"Inverse Vee bottom shape - Generous vee and double concave configuration in the nose to clear the chop and create a smooth ride, transitioning to inverted vee in the tail for increased grip and power in the lower wind range and better control and stable trim when powered."

"....the Plastic Machine of 1967 [Going Vertical board] was perhaps the most radical anti-log ever, ushering in the most rapid design period in surfboard history. Greenough was right by suggesting Nat and I [Bob McTavish] try adding vee in the tail of our logs of the time. The concept would allow wide-tailed boards to roll more easily onto the rail. Nat was actually the first to incorporate the vee into his 9'5" Aussie Titles winning board at Bells in 1967. See him just rip in Hot Generation.... the vee worked, allowing Nat to carve a wide-tailed Sam/Involvement Template on a six-foot Bell's face. A real breakthrough! However, vee bottoms softened and morphed into Trackers, miniguns and Bluebirds, almost disappearing for many decades, although soft vee remained in all shapers' toolboxes for pulling out where necessary, usually to keep a gun in the face or to allow a glider to roll. However, we at McTavish never stopped fooling around with them." www.mctavish.com.au/blogs/stories-2/beatnik

Honolua Bay , Maui 1967:

eos.surf/video/entry/video-honolua-bay-1967/

Spiral Vee in Bombora Protos and Bombora New Toy 1982-83:







Not sure whether spiral vee still used in modern windsurfing boards. Sounds cool though.

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Mark _australia said..

Spiral vee is old surf term for vee increasing towards tail. If U look at it from the tail upside down on the shaping stands, and drag a straight edge toward you the straight edge drops with rocker and horizontal angle increases with vee so it appears to 'spiral' which may be the origin of the term when that guy whatsisname invented in the 60s or 70s

Anyway we don't do that in windsurfing anymore - quite the opposite

As the same guys who invented spiral vee long ago also did double concave some people believe that it just means vee with double concave in tail but that's not corrext. Possibly why starboard claimed spiral vee in the EVO boards? I dunno as I haven't seen an Evo for ages but I do know that no modern windsurf board I've seen has increasing vee toward tail

The early model Kodes were advertised with a spiral V as well.

I figured they meant the same, but opposite. They had no (or very little) concave upfront so as the V reduced from the middle towards the tail the "spiral" was inwards, not outwards.

I'd take scoop rocker to be concave up front, intended to help pop the board onto the plane before the bottom shape under the middle and tail.. Never been convinced it does much (people say it is supposed to help air flow under the board to initiate planning and pop over the bow wave). Maybe on wide flat slalom boards where you are flying on the fin once planning ?, maybe on foils ? but never felt it does much on smaller boards that have single V and smaller fins.

Is the scoop rocker refined to the nearest 0.1mm ?


In geometry a spiral transitions from straight to curve. Spirals having changing rate of curve / an origin that changes as you move along the spiral line. So technically the spiral V should/could refer to the transition from flat to V being through a spiral rather than a tangent. But the V is never a constant radius curve in any axis anyways so it doesn't make sense like that.

Now Martin has thrown it in the mix - vee angle or absolute vee measurement at the rail?
I was referring to the latter as the traditional view from the inventors of the term as I understand it.
Seems it's used a few slightly different ways and who woulda thought starboard marketing terms

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Shifu said..
And... what the heck is "inverse vee"?

As in how would you interpret this www.fmxracing.com/veloce-ltd-116/
"Inverse Vee bottom shape - Generous vee and double concave configuration in the nose to clear the chop and create a smooth ride, transitioning to inverted vee in the tail for increased grip and power in the lower wind range and better control and stable trim when powered."

Makes sense to me, I was thinking of a concave tail the other night.
Especially for very flat water speed sailing.
Water displaced to the side in the wake = a loss of lift, leading to more whetted surface to make up the deficit.
I wasn't thinking inverted V though, more an accelerating curve towards the rails. This should help minimise sideways displacement, and increase lift. It would also give the rail more "bite" in high G turns.
I would only do it between footstraps though, and I haven't worked out the transition phases between +V forward and behind the straps.

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decrepit said..

Shifu said..
And... what the heck is "inverse vee"?

As in how would you interpret this www.fmxracing.com/veloce-ltd-116/
"Inverse Vee bottom shape - Generous vee and double concave configuration in the nose to clear the chop and create a smooth ride, transitioning to inverted vee in the tail for increased grip and power in the lower wind range and better control and stable trim when powered."

Makes sense to me, I was thinking of a concave tail the other night.
Especially for very flat water speed sailing.
Water displaced to the side in the wake = a loss of lift, leading to more whetted surface to make up the deficit.
I wasn't thinking inverted V though, more an accelerating curve towards the rails. This should help minimise sideways displacement, and increase lift. It would also give the rail more "bite" in high G turns.
I would only do it between footstraps though, and I haven't worked out the transition phases between +V forward and behind the straps.

I like your single concave idea and it's making my head hurt. I believe some wave boards have single concave in the middle of the board. So many questions and changes to the board to implement the idea. On a fast board, if more water is pushed into the center, creating more lift, could that reduce bite because the board is sitting higher on pushed up and possibly aerated water? Would this cause spin out if air gets under there? The center line rear rocker would have to change. How would this work with a narrowing tail, would you have to put less rear rocker at the edges as to not effectively create more V? It would have to be exact, for the concave and the rails, to end up a smooth water flow. Unless the concave goes out the back. I think with V or spiral V or what I thought was spiral V, the excess water comes out the sides and regulates the lift depending on the amount of V. If you trap some of that water, I have no idea what would happen. There is probably a perfect formula that will let it work. I wouldn't know where to start. Going from positive V into negative V or the other way around, there would have to be a flat blending stage. This must be done on wave boards that have a single concave in the middle.
We need a board build decrepit???

Single concave in mid section increases rail engagement in a bottom turn considerably. The lift is not as relevant as that digging in during a turn

I'm getting a concave in my brain.

currently toying with a similar design.

basically a single concave with a quad concave inside the single under the feet
2-3mm single and 0.5 for the doubles. That with a small flat or chine either side of the single for stability.
probably wouldn't do it for a speed board. A speedboard with no v could possibly be sketchy at speed

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Imax1 said..

decrepit said..

Shifu said..
I And... what the heck is "inverse vee"?

As in how would you interpret this www.fmxracing.com/veloce-ltd-116/
"Inverse Vee bottom shape - Generous vee and double concave configuration in the nose to clear the chop and create a smooth ride, transitioning to inverted vee in the tail for increased grip and power in the lower wind range and better control and stable trim when powered."

Makes sense to me, I was thinking of a concave tail the other night.
Especially for very flat water speed sailing.
Water displaced to the side in the wake = a loss of lift, leading to more whetted surface to make up the deficit.
I wasn't thinking inverted V though, more an accelerating curve towards the rails. This should help minimise sideways displacement, and increase lift. It would also give the rail more "bite" in high G turns.
I would only do it between footstraps though, and I haven't worked out the transition phases between +V forward and behind the straps.

I like your single concave idea and it's making my head hurt. I believe some wave boards have single concave in the middle of the board. So many questions and changes to the board to implement the idea. On a fast board, if more water is pushed into the center, creating more lift, could that reduce bite because the board is sitting higher on pushed up and possibly aerated water? Would this cause spin out if air gets under there? The center line rear rocker would have to change. How would this work with a narrowing tail, would you have to put less rear rocker at the edges as to not effectively create more V? It would have to be exact, for the concave and the rails, to end up a smooth water flow. Unless the concave goes out the back. I think with V or spiral V or what I thought was spiral V, the excess water comes out the sides and regulates the lift depending on the amount of V. If you trap some of that water, I have no idea what would happen. There is probably a perfect formula that will let it work. I wouldn't know where to start. Going from positive V into negative V or the other way around, there would have to be a flatblending stage. This must be done on wave boards that have a single concave in the middle.
We need a board build decrepit???

It can cause spin out if air runs down the leading edge of the fin but typically mono concave are paired with quads anyways.

can't say I agree with v leading to loss of lift. V boards ride higher than mono concave. Thats why v is so handy. The faster you go the less wetted surface plus you have the v to maintain control and improve turning

Peter Nitschke built a channel step speed board and a few slalom and formula channel step boards,. ive ridden a few of them.. an interesting design. You need the v to feel comfortable,

on the same lines. I had a freestyle board I was biology with Peter which had a flat bottom. I didn't get along with it and by the 3rd iteration it had minimal v to fix the tracking issues.

What was the idea behind the early starboard hypersonics (hypervomit)? It had a golf ball like hull.never ride one,but heard they were smooth in chop. One of the ugliest boards l have ever seen.

So the answer is we sometimes THINK we know what these terme mean, but we might not ACTUALLY know... ?

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Yup. Spiral vee is particularly useless
Just look at where board designer Martin says vee increases to tail - correct as he uses angles to design
Yet I say it doesn't as I dont shape by angle I shape to an absolute drop at rail compared to centreline - correct also in that the vee in millimetres reduces toward tail

So in the 60s did they use vee angle or a measuremebt at rail when they invented spiral vee?

I dunno

But I can say with absolute certainty that when they write spiral vee in board advertising it's possibly BS
Perhaps

I was previously taught and have also read that spiral v goes from slight v under the mast to deeper v at the fins because of double concaves getting deeper towards the back of the board.

Reverse v is the opposite. Deeper v under the mast to flat between the fins.

Where the rocker at the rail is curvier than The centreline rocker and there are no concaves i believe that's a panel v. Aren't panel v and flat v the same thing?

Wasn't scoop rocker made up by starboard and meant an accelerating rocker towards the nose? Not sure.

No its just a vee thing and does not need concaves.

Common misconception is that it involves concaves, only as the same couple of guys also invented double concaves at similar time.

www.swaylocks.com/forum/49614/spiral-vee-please-can-some-one-explain-idiot-guide

^^^ that has opinions from a few people who were there and a couple good pics. Look at the green board - true old school extreme spiral vee and if you made a WS board like that it would be useless. Then others say it had most vee near the fin and it reduced near tail. They were also there at the time.

Luckily there was no forums then

It's hard to say from that page as both ideas of with and without concave are put forward. From people with a lot of experience.

will see if I can find something from bob mactavish. I'm pretty sure a lot of this confusion comes because shapers would only tell half of their method and that became folklore.


pity the Byron shop is more shop than factory these days. Otherwise I could just go ask.

I don't know the origins of the term but to me spiral v describes a V angle that is not constant....it varies along the length of the board. Whether you measure it with an angle ( as I do due the CAD system I use) or as the height at rail vs centreline is neither here or there......it means the angle of the V is not constant.