Soft boards flex. Flex is bad. When you’re paddling, you want efficient energy transfer to move you forward, not energy loss to bouncing your board up & down. Just like riding uphill on a suspension mountain bike. Agree or disagree?
I think you need a bit of flex to handle surface chop when you are moving really fast - like the mountain bike going down the hill. Also I suspect that a bit of flex gives you a bit more speed out of turns as you unweight. But with flex you need memory - ie your board bends a bit and returns to it’s original shape quickly. I think boards lose memory with repeated stress so a new board that flexs a lot might not feel so snappy after a bit of use - which would be a bad thing. How much flex and how to get the right amount for an individual using design and/or materials? I wouldn’t know where to start.
The original soft boards were soft skinned top and bottom, with some form of stringer made of a horizontal layer of fiberglass. These had some nice flex to them with, I suppose, memory. The properties of the soft skin and blank/core - closed cell plastic foam - were pretty solid too, although this was the area that eventually broke down from wear and environmental degradation (sun, sand, age). Hard bottoms and the slick skin bottoms - I never used any of these enough to tell a flex difference. By the time slick bottom skins came in, so did what I considered to be terrible tri-fin set ups. In case anybody wonders I already had a decade of hard board experience before sft boards came out. One of the really nice properties of the original soft boards (at least the Morey/Doyle Soft) was the way they absorbed shock. I’m pretty sure this was via the soft material and lack of hard bottom. They just blew through surface chop. The closest description I ever heard or read to this feeling came from Leonard Brady (I think) in Surfer magazine writing about surfing Waikiki on a real old wood board - I recall the writer saying the weight of the board blew right over any chop like it wasn’t there. No flex on that board, though.
I think boards need a certain amount of flex to keep from busting every time we go over the falls. Hence the wood stringer. Maybe you’re mainly refering to soft boards. Not sure about those.
Interesting comment Stephen made about boards losing their memory after a time. This is called fatigue. I’ve personally noticed that boards ride better when new. They have a spring that older boards don’t because older boards have lost their original feel after being “flexed out” like an old bow. What’s really interesting is that this has led to the perception among surfers that shapers are moving forward with design at this break neck speed and that advances, board to board, are simply incredible. What actually takes place in most instances is that the old board fatigues at a relativly slow, unnoticable rate and then suddenly there’s this incredible new surfboard that outperforms the old, trusty magic one it’s replacing. This commonly leads to team guys coming into the shaping room exclaiming, “Dude, I thought the last one was hot but this one is even better. You rule dude!” And if your a shaper that is unaware of fatigue, and the effect it has, you then have trouble that evening getting your head out through the shaping room door. If you are aware, there is one tip I’d like to share. DON"T tell your team guys.
…Surfboards…Like in my skateboards,I prefer "spring"not flex.Herb
I like that term “spring”. My latest board is a 7-6 Surflight, which which has a composite core with controlled flex which has that “spring” characteristic designed into the tail. By surrounding the core with a flexible foam and finishing with a polyurethane outer surface they’ve managed to avoid the fatigue problem that occurs with standard surfboard materials. The board feels alive as it loads and releases. It seems to anticipate your manuevers since it responds so quickly. Any negatives? Board care is important because the outer surface will mold slightly to the surface it lies upon, so don’t lay it down on the pavement - although it will puff up again to its normal surface if left in a hot car for a while. In general, the board is stronger and almost never picks up dings from banging things. The jetty at Bomburras did almost no damage to a similar board after it escaped from my leash…I hate to think of the work it would have taken to repair a fiberglass board. Anyone interested in this technology can check it out on their website. They make most kinds of surfing vehicles, not just surfboards, and make a great effort to customize their technology to the needs of the surfer. So my put is that flex is bad only if badly done. One longboard I tried had the flex pattern extended too far forward, resulting in the very strange sensation of the board stalling out everytime I started to get up because it was bending in the middle. That was early in their design phase tho’; I understand they’ve solved that problem. An aquaintance who has a Surflight 9-0 LB pintail has been heard to mutter “keep your hands off my magic board.” http://www.surflight.com
Greg is right on when he talks about fatigue. Skateboarders call it “pop”. The same is true of your wetsuit. After you wear it for a few months it starts to develop tiny leaks. After a year you buy a new one and think “wow, this new Blah blah suit is the bomb!” With surfboards, I have found that the breakdown occurs for several reasons. The biggest is that the glass starts to lose contact with the foam. This can be do to pressure dings, or bad glassing, or just flex (fatigue), but basically it is inevitable. The board as it flexes is stressing the bond between foam and glass. The stiffness of the board is partially attributed to the bonding of the skin, so when the skin comes loose, the stiffness suffers. Even tiny little areas of bond breakage add up. That’s why when you see a broken board, you often see a large strip of lamination attached to one end, the extreme flex before fracture has stretched and broken the bond from this area. Flex is an important part of the performance of a surfboard. Without flex, you would find generating speed and recovering from turns very difficult. the board basically loads up like a spring when you turn or pump, and then unloads, and springs forward. Granted the flex is small, but it is more than you think. Put your board deck down on the floor and press lightly with your foot in the middle to see how much it flexes with little effort. Don’t stand on it! Every time you pump or turn the board, you are putting a fatigue cycle on it. How many cycles until it starts to feel dead? Who knows. With a traditional board, the flex and twist is controlled by the stringer, and the shell (glass). The Surflight (previously mentioned) is completely designed to control flex and twist with an internal structure. Basically it is a carbon fiber snowboard like spring. The surrounding foam and PU coating are there for shape and fit. Sort of like the seat in your car, you can’t see what is really doing the work. Because carbon has excellent fatigue properties, and can be easily tuned to have more or less flex, it is a great material for this. The Surflight is a great board, but it is quite different from anything people are used to. As Greg knows from working with Epoxy, if it is done right, it is less brittle, and can have excellent fatigue memory. Combined with a flexible foam, and a good bong, and you can create a very strong board, that is light that will keep it’s pop. If building a shell structure, the key is to have as little deviation in flex between the shell and the core as is possible. Otherwise the board wants to delaminate itself as it flexes. Now for the real question! How will we begin to measure flex in different areas of the board, translate that data in “the right amount of flex”, and duplicate it? Suffice to say, if we can do it, your order forms will get a lot mor complicated. I’ll have an 8.5 degree flex in the midsection, with 5 degree flex 20 inches from the tail, and a nuetral nose.