Staged vs continuous rocker.

jkb

Tom Curren status
Feb 22, 2005
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Central California
Big flat spot no worky for everyone.

Stable platform but sensitivity is reduced.

Good for guys who like to use blunt force trauma on a wave......maybe not so much for those that rely more on timing and placement.
 

One-Off

Tom Curren status
Jul 28, 2005
14,188
10,354
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33.8N - 118.4W
I know a local shaper who talks about the "speed box" in the middle of the board. He swears by it. Putting a single concave in the middle achieves the same thing.
 
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Duffy LaCoronilla

Duke status
Apr 27, 2016
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For HPSB

“Staged” rocker (flat section somewhere in the middle) - single to double concave.

”Continuous“ rocker - Single all the way, single to flat, single to flat to vee (for quads)
 
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One-Off

Tom Curren status
Jul 28, 2005
14,188
10,354
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33.8N - 118.4W
Reducing the apex reduces the lift in that area .

Entry angle on my boards reduces as it nears the center to none - the the exit begins ! ;-)
I'm always a little skeptical of the use of the word "lift." I remember Roy calling out Daniel Thompson for his use of aero/hydrodnamic terms. I actually thought Roy was right in that instance.

This is how I understand lift-

main-qimg-72907814968f99677386a8f59fa50977-c.jpg

Good old Bernoulli. But this assumes a pressure differential between a top and bottom surface, a condition that does not exist with a surfboard bottom. And even assuming that a single surface produces lift, wouldn't a surfboard's rocker be like this?

main-qimg-72907814968f99677386a8f59fa50977-c.jpg

So the lift is pushing the board down into the wave?

And this- "Reducing the apex reduces the lift in that area "- defies the well known anecdotal evidence that boards with less rocker are faster than an otherwise identical board with more rocker.

That said, I do prefer a continuous rocker. My favorite blanks are the EAs. (Arakawa?). This is the blank I'm working with right now. I think it is pretty continuous-
71EA-with-measurements-466x702.png

And even if I don't necessarily buy whatever hydrodynamica mumbo jumbo a shaper purports to manipulate, it doesn't mean I think their boards don't work. I know Tomo's and Greg's work from the anecdotal evidence. I'm not picking a fight with you , GG, but feel free to explain your statement or tear apart mine.
 

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Mr J

Michael Peterson status
Aug 18, 2003
2,260
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Regional Vic, Australia
I agree with all your physics llilibel. Bernoulli can't be applied because there is no top lifting surface on a planing vessel. Yes where water forms laminar flow across a convex rocker (taking into account diagonal flow) then there will be downward suction. Higher rocker => greater suction and less lift. The "apex" or bend or whatever we want to call it where the two stages of plane meet will be a source of increased suction.

My attempts to try and understand why our surfboards do not head towards the bottom of the sea has led me to believe the following things:

The water is not laminar everywhere - there is a massive ridge of high pressure called "the spray root" i.e entry point of the hull which starts at the nose scoop and forms approximately a diagonal line down the board.

Water curving outwards towards the rail can encounter a flat or even convex path (illustrated by the MC trick of placing a straight edge diagonally across high rockered/high concaved boards).

Also as soon as we step on the tail of high tail rocker/staged section any suction gets replaced by lift when the angle of attack increases and Newton's third law says that the deflection from the increased angle of attack will cause lift.
 

silentbutdeadly

Duke status
Sep 26, 2005
33,651
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Tower 13
I have little to no understanding of this with surfboards but I have experience with wakeboards. I liked three stage rocker on wakeboards cause I rode steeper wakes and it translated to my riding style better. continuous rocker seemed to be better suited for mellower transition of boat wakes (manufacturer speciifc).
Just rambling thoughts in my head but I wonder if I would like a staged rocker in steep waves a continuous in mellow point style waves?

i'm embarrassed to say I don't know what kind of rocker any of my boards have in this regard
 
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casa_mugrienta

Duke status
Apr 13, 2008
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Petak Island
I have little to no understanding of this with surfboards but I have experience with wakeboards. I liked three stage rocker on wakeboards cause I rode steeper wakes and it translated to my riding style better. continuous rocker seemed to be better suited for mellower transition of boat wakes (manufacturer speciifc).
Just rambling thoughts in my head but I wonder if I would like a staged rocker in steep waves a continuous in mellow point style waves?

i'm embarrassed to say I don't know what kind of rocker any of my boards have in this regard
Flip and mostly flat areas of rocker are a tell.
 

One-Off

Tom Curren status
Jul 28, 2005
14,188
10,354
113
33.8N - 118.4W
Entry angle helps create initial lift up to plane - angle hand upward out car window to experience this ;-) - No foil involved

Tail rocker controls that planing effect and release of planing pressures , still entry and exit angles all thru the back half depending on the angle the board is riding on .
Thanks for the clarification. I guess I would have called that "planing" rather than lift , but a quick google says it is lift.
But now your apex term is confusing me. Is that where you perceive the rocker changes more drastically? Would staged rocker have two apexes? Also doesn't rocker apex change position depending on where you're standing on the board, like Mr. J mentioned above? Would you call your rocker continuous or staged?

In pedagogical terms, you need to create some "scaffolding" for us slow learners...
 
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