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Pocket board rocker

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RichR2
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Pocket board rocker

Postby RichR2 » Wed May 02, 2018 4:00 pm

I'm starting to plan a pocket board (125 x 48) build and was hoping for some input on how much rocker to build in.

I'd be very interested if anyone has measured how much rocker there is in the Groove Skate foilboard. It seems to be a lot more than other pocket boards Ive seen. Also, what about rocker in the tail? Is there any benefit in building some in and how much.

Thanks for any input you can give me.

BWD
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Re: Pocket board rocker

Postby BWD » Wed May 02, 2018 4:30 pm

I've read a bunch of posts and blogs on these and want to make one myself.
Nose:
Most builders seem happy with 10cm+ of nose rocker. Almost as much as a lot of surfboards, but in a tiny board.
Keeps the nose from going down the hole when you come off foil.
Opinions vary about tail rocker.
for the smallest boards, zero tail rocker may mean getting the most out of your available planing surface.
The shortest thing that will plane is nearly flat and gives up most nose rocker.
And touchdowns are not likely to be super easy.
Tail:
For slightly bigger (125? 135?) to full size (145+) boards, it will probably be helpful to have 1-3cm tail rocker also.
The reason is some tail rocker helps maintain a constant AOA with the whole planing surface as you ride in a "semiplaning" mode from start up to the foil's lift-off speed.
My thought on this is that as the board moves from displacement or plowing to semiplaning, it creates a transverse wave and it's good if the board is close to "fitting" this wave to minimize the amount of drag induced by a rocker profile out of wack with the pressure distribution on the hull surface. if that make sense to you...
So for a board 125x48, if the tail is wide, it could have 8-10cm nose rocker and a bit of tail rocker too, depending on outline shape, and all the other variables (outline shape, foil used, user weight, skill, preference, water surface conditions etc etc)

RichR2
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Re: Pocket board rocker

Postby RichR2 » Wed May 02, 2018 7:13 pm

Thanks BWD, really useful info. Has anyone measured how much rocker the Groove has? Be interested to know if it's gone even more extreme than the 10cm. It certainly looks like it might have from the video on their website.

revhed
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Re: Pocket board rocker

Postby revhed » Thu May 03, 2018 1:35 pm

P1010028.JPG
For your consideration, Ketos like.
R H

RichR2
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Re: Pocket board rocker

Postby RichR2 » Thu May 03, 2018 2:40 pm

Is that 10 or 13 cm and over what length. Have you finished and tried it yet?

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Re: Pocket board rocker

Postby TomW » Sat May 26, 2018 5:22 pm

I've just finished a pocket board. It has 10+ cm nose rocker and 30mm tail.
I think my nose rocker is too abrupt, should be more gradual towards middle of the board.
My hypothesis after making 2 foil boards is that tail rocker primary benefit is it changes AoA of board to foil, so when you touch down, the board touches water around front foot, not at nose first. This allows recovery.
If board touches at nose, it is tippy over nose, and first little chop it buries it.
If board touches at front foot, board is more stable, has some surface to to push back, and nose rocker is in reserve to get over chop.
This AoA of board is dependent on how foil AoA rides in relation to plate attachment. Foils " neutral ride" AoA varies greatly, so one foil might be perfect, other will make board nose dive.
2018-05-13 17.21.49.jpg
2018-05-13 17.21.13.jpg


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