This board has been circling my head now for about two months; but it's a project as a whole that's been a nagging question for me since my first experiments with this type of particular flex about four years ago.
What I'm after is a kind that twists around the center of the board, changing the outline, rocker and projecting out of turns with the same type of motion as a Flex Spoon. Imagine a rail line lifting from the tail; altering the rocker curve and outline, then when unloaded, springing back to it's normal shape....Awesome. I know.
The problem is with a surfboard's thick center, you can't take the same theories that the spoons use (think: a tuning fork shape of stiffness around a flexible center) to achieve the same flex pattern; it's totally backwards and only stiffens the board (think: the greater the distance between two laminates, the stiffer the part will be).
I've been through the parabolic stringer thing and I'm not sold, it's not as flexy as I want...just not enough for me and what I'm thinking of. This brings me back to where I started. Here is my new project-in-progress; I've named it Stage III.
I built a 1/8" thick Paulownia skin that is shaped to use the nose and tail areas of the board to act as a torquing forces around the weaker center. That was then sucked into the area that I routed out of the deck so it would sit flush:
In the bag ^
After removing it from the bag the board felt way too stiff so I did some brainstorming and took the volume out of the sides of the board, in order to lessen the distance between my final laminate layers. This will be replaced with EVA foam after glassing:
That got the board much much closer, but it didn't blow me away until I decided to route the center out of the paulownia patch to allow the shape to work as two individual arms instead of one twisting body. the strength nose-to-tail is 99% unaffected, but allowing MUCH more twist. That cavity was then filled back in with EPS foam:
This thing threw me for a loop today but with a whole lot of brainstorming it's transformed into something more than I could have thought up. I've gotten too deep into the 'plan' with some earlier boards, this one i've decided to work as I go and see what I can do on the fly and work as I go with the flex pattern.
Tomorrow I'll be bagging the deck Kevlar and 2oz fiberglass on...I'm so pumped....
5 comments:
So what did you start with? Was it basically a stringerless shaped hull that you pulled the core out of to add your wood insert? What are the dimensions of it now?
it was just a stringerless EPS blank, then glassed the bottom with kevlar (no laps) then added the wood to the deck and so on and so forth.
the deck lam is in front of me right now mid-vac-bagging!!!
Just a though, but wouldn't the extra curve in the deck cause the whole board to stiffen after lamination, a little bit like deck channels?
that was a huge concern because thats what happened to big black nothing, but i made sure that ANY severe curves were placed in the center of the board, so the shape could still twist around it.
the board is very stiff nose to tail, but it does have a very interesting amount of twist since it has cured now with the deck on it!!
stoked :)
Great project. I appreciate your open imagination. Look forward to following your progress Ryan.
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