it works better than anything else you can imagine …
it justs takes time to work out the eleven secret herbs and spices …
I get the idea that a board should flex in some places and be stiff in other places, but I have no idea of where the flex should be placed and where the board should be made stiffer. Where (and why) would you place the flex and stiff area on these three imaginary boards:
Small mushy wave board
Typical 2-4 foot, semi-hollow beachbreak
Big, powerfull wave board
Please don’t limit yourself to these three boards. I just included them to get people thinking.
It seems to me that moderate flex in a surfboard can be a good thing. As rocker increases a board becomes easier to turn and will climb the wave fast with more power so a board that flexes moderately when you weight it to turn will be more responsive. The other up side of this picture is that when the board is not weighted to turn it will have less rocker and the board will trim more freely. This principle was use by George Greenough on the flexible spoon he rode on his knees in “The Inner Most Limits of Pure Fun.” It’s one that is still used in boards today.
When it comes to fins that’s another matter entirely. The conditions and the board will dictate how well a flexible fin will work. Generally speaking bigger waves want stiffer fins. But saying that some boards simply surf better with a fairly flexible fin or fin set-up.
I have a three stringer 9’0" that has a nice flex to it and I’m sure that this in one of the reasons the board is so responsive in small waves.
I hope this will put the thread off in the right direction and am sure that there are many who greater experience than I who can add their expertise to the picture.
Bert talks about making one part of the board flexible while making other parts of the board stiff. How many part of the board do you think flex (stiff or not stiff) characteristics might be important:
rails
nose
tail
mid board
deck skin
bottom skin
fins
For instance, on a big wave would you want certain parts to flex while other remain stiff. I am wondering if there are general rules of thumb like Halcyon’s “big waves = stiffer fins”.
One thing you can be sure of in surfing is that there will be exceptions to any general rule.
With board flex my take is that if the whole board flexes fairly equally you have the best of all worlds ~ if in fact you want a flexible board. Some boards flex more than others of course.
I’m making a set of fins right now for a 6’4" tow-in twinzer that weighs in excess of 25lbs and that board was too flexible for the rider when it was first built so a layer of epoxyed carbon fiber about 2 inches wide was added to the middle 4 feet of the board. Now the flex pattern is more suitable.
When I comes to board flexibility you can almost always reduce it once the board is finished but you can’t more into it very easily.
As I understand it flex will reduce the chance of the board breaking. I think that flex must be important in storing and releasing energy. If this is true, it seems that you would want a stiffer tail on the board but I don’t know
Flex…my love/hate subject…Im intrugued by it, but also think its over-rated for most common surfing situations…Bert is the Guru here and the archive is just loaded…his core argument is that it offers more range out of a board…honestly, with 8 boards in the quiv I dont need much range in one stick…it seems that “where” is not as important as “how much/stiff” or “how fast/slow” or “how ringy/dampened”…whew! Just when you think youre understanding it, you learn that Bert uses concave decks…double whew!! Simpler is better…stiff/fast in grovel…semistiff/slow in big juice…be one with your deck…
the 8’’ thick beams in the tall ships flex onder load
the trick is to allow this lively feature of the compositios that makes up the board work for us in a positive way
greg L. has talked divisively about the styro -point blank experience because of it lack of flex
the offset stringer changes the flex dynamic Im sure ,wether they are close or far appart
AND>>>and while we are extrapolating …these flex disscussions are two dimentional until you engage the tortion or natural twist dynamic into the mix which just makes the geometry left braynerz spin into the whacky equation twilight zone and the fin box guys choke because of the dampening of the lateral twist present in a glass-on reinforced construction plan…ambrose …stayin up late
you surf , and feel out where you need extra stiffness or flex , different manouvers require more or less flex from different parts of the board , then different weight riders need flex tuned to there weights for ultimate spring …
look what happens when a beefer trys using a springboard diving board , the thing doesnt spring back , his extra weight has overpowered the springboards ability to bounce him back …
i have customers at 240lb doing airs youd normally see fly weights doing … coz the flex is tuned for there weights …
would the result of not having stringer through the length of the board lead to a snapped board instead of a buckled one?
A buckled board is a result of a board flexing more than the materials of that board can handle. GO pick up a ski or a snowboard. It’s got a negative rocker. If you put some load on them they will easily outperform the rocker of just about any surfboard in the world. Now, did it break? I think the stringer is there as much to prevent buckling as to stiffen the board up, both to prevent breaking. I believe most boards buckle as they break, but I might be wrong. regards, Håvard
different manouvers require more or less flex from different parts of the board
For me, this is the real question. Take something as simple as a bottom turn. Which part of the board do you want to flex? I would think that both a lite surfer and a heavy surfer would still need the board to flex the same amount in the same spot on the bottom turn. The only difference is that the lite surfer would need a more flexy material because they wouldn’t have the same amount of mass to deform the board. Using Bert’s diving board analogy, in order to spring out of the bottom turn with the most energy in tack (the flex is storing the momentum you gained moving down the face of the wave) I would guess that the tail (but it could be the back half of the bottom skin) would need to be tuned in the the surfer’s weight. There doesn’t seem to be much advantage to composite boards unless you make them strong where they are needed and lite where strength isn’t an issue. In traditional boards this might be accomplished with a deck patch so that the glass is thicker were you need it.
Greenough’s stuff and my poor excuses of flexie kneelos and standups showed me that you want the rail rocker to flex but the stringer rocker to stay really stiff (except for the last 6 inches or so). Also, most of the flex is in the tail portion of the board. I never really got much of a kick or rebound from stuff flexing back to a neutral shape. Flex is great for making a stiff design (read: flat rocker) easy to turn. It also dictates a carving and big turn style of surfing.
I wonder about flex’s compatibility with the modern tri-fin set up…A thruster is impossibly easy to turn already. The area that needs exploration is puting a flex tail on a longboard. I always see flex tails stuck on stubbies or other short boards that are fairly easy to turn just by their length. Try sticking one on a flat rocker’d single fin cruiser and turn it into a fairly high performance board without sacrificing float or the need for false decks.
The area that needs exploration is puting a flex tail on a longboard. I always see flex tails stuck on stubbies or other short boards that are fairly easy to turn just by their length
What would make something a “flex tail”. I’d be interested in getting more performance out of a bigger board. I haven’t heard much about flex characteristics of a board’s nose. Is this because it does not affect the performance that much and its just important that its lite? Would it be benificial to have flex when you’re nose riding? I would guess that the board springing back quickly wouldn’t be that important.
I was thinking about why Bert would concave the deck. The obvious reason is it would lower the weight and in increase your feel of the water. I wonder if an additional benifit of a concaved deck is that it would increase flex when making turning maneuvers. With a traditional domed deck the board would fight flexing. With the concaved deck the board could store energy from the turn and return it when the deck returns to normal. This would be “spring” you out of your turns.
