Hey guys - I’ve been contemplating this one for awhile and can’t seem to pin it down. When a blank is custom ordered with +/- tail rocker, does anyone know how pre-stressing the blank as it is bent to conform to the stringer affects flex and liveliness in the finished product? I’m sure that stringer type, tail thickness, deck configuration (dome vs flat) and glassing play a part as well. It just seems that a natural rockered blank will have a certain up and down “give” to it while a blank that has been tweaked up or down will have a different flex/rebound characteristic. I’m thinking of how a Greenough spoon flexes under pressure and then snaps back to a speed rocker and how this phenomenon could be dialed in to a surfboard with tail rocker manipulation in the blank. Maybe this is the key to those “magic” boards that are shaped exactly like another that doesn’t seem to have the same zip? Or do I need to call Swayloholic’s anonymous? (My name is John and I’m a Swayloholic…)
Hey guys - I’ve been contemplating this one for awhile and can’t seem to > pin it down. When a blank is custom ordered with +/- tail rocker, does > anyone know how pre-stressing the blank as it is bent to conform to the > stringer affects flex and liveliness in the finished product? I’m sure > that stringer type, tail thickness, deck configuration (dome vs flat) and > glassing play a part as well. It just seems that a natural rockered blank > will have a certain up and down “give” to it while a blank that > has been tweaked up or down will have a different flex/rebound > characteristic. I’m thinking of how a Greenough spoon flexes under > pressure and then snaps back to a speed rocker and how this phenomenon > could be dialed in to a surfboard with tail rocker manipulation in the > blank. Maybe this is the key to those “magic” boards that are > shaped exactly like another that doesn’t seem to have the same zip? Or do > I need to call Swayloholic’s anonymous? (My name is John and I’m a > Swayloholic…) John, Polyurethane surfboard foam is unfortunately not well-suited to withstanding the expansional and compressional stresses of tuned, long-term flexing, i.e. it rapidly breaks down. In part, that
s why George moved away from using fiberglass/resin and foam in his kneeboard rails/chines, to end-grain balsa, and finally to a high-density structural foam, carbon graphite and high temperature-cure epoxy composite. Through this combination, his "edge" kneeboards finally achieved the tuned memory that he wanted, with the added benefits of enhanced sensitivity, lighter weight and long-term, structural integrity. Sadly, a conventional fiberglass and foam design may be "magic", working and feeling great at first, yet can often become mysteriously "dead" in a relatively short time... and sometimes, certain boards will initially feel stiff and inhibited, but later develop a bit more flex, becoming increasingly lively and responsive... just before they snap... This area of surfboard construction is in need of much more experimention, with the likely addition of some new, strong, light, resilient and cost-effective core materials, particularly in respect to retail production. I
m ready for those S.A. meetings that you mentioned, too…
Yes,Brothers…it is time to enter the twelve (cross) steps program. (sorry, eh!)
No 12 step programs needed in such a healthy environment. A very very good question and or observation. Clark foam didn’t even look too much into this until the advent of shaping machines. Shaping machines found a thorn in the side once the foam flexed. Everyone knew that it flexxed and it depended on various factors. The obvious on is that as you take more foam off the blank and get into the softer foam…flex changes…you get the drift. Not too mention Daves great explanation of “break down”. Unfortunately, that is the state of affairs with polyurethane foam. When I shape a board I trie to get a close tolerance blank(as close as possible to avoid the relaxation of rocke du to this flex. I heard of one guy actually flexing his board and keeping it in place with tention from a wire pinned to the deck side of his board as he glassed it…I love this place…fishing poles to make templates…home made fins made of wood, triple-concave, spiral vee hull bottom twinzers!!! Maybe a 12 step program isn’t a bad idea!!!
Step One: Spend more time with the wife and kids. ) What is the material that “Y” is using in the Swizzle?
Hey guys - I’ve been contemplating this one for awhile and can’t seem to > pin it down. When a blank is custom ordered with +/- tail rocker, does > anyone know how pre-stressing the blank as it is bent to conform to the > stringer affects flex and liveliness in the finished product? I’m sure > that stringer type, tail thickness, deck configuration (dome vs flat) and > glassing play a part as well. It just seems that a natural rockered blank > will have a certain up and down “give” to it while a blank that > has been tweaked up or down will have a different flex/rebound > characteristic. I’m thinking of how a Greenough spoon flexes under > pressure and then snaps back to a speed rocker and how this phenomenon > could be dialed in to a surfboard with tail rocker manipulation in the > blank. Maybe this is the key to those “magic” boards that are > shaped exactly like another that doesn’t seem to have the same zip? Or do > I need to call Swayloholic’s anonymous? (My name is John and I’m a > Swayloholic…) (Swayloholic, . . . funny stuff.) Excellent question. – In my humble opinion, that a pre-loaded stress in the blanks helps (and even makes) the overall stress factor. If the blank wasn’t pre-loaded during stringer glue-up, the flex would be so soft it would be like riding a soft-top board. (on Shortboards) (I’m divorced, so I’m ready for step two, forum god.) Jake
No 12 step programs needed in such a healthy environment.>>> A very very good question and or observation. Clark foam didn’t even look > too much into this until the advent of shaping machines. Shaping machines > found a thorn in the side once the foam flexed. Everyone knew that it > flexxed and it depended on various factors. The obvious on is that as you > take more foam off the blank and get into the softer foam…flex > changes…you get the drift. Not too mention Daves great explanation of > “break down”.>>> Unfortunately, that is the state of affairs with polyurethane foam.>>> When I shape a board I trie to get a close tolerance blank(as close as > possible to avoid the relaxation of rocke du to this flex. I heard of one > guy actually flexing his board and keeping it in place with tention from a > wire pinned to the deck side of his board as he glassed it…I love > this place…fishing poles to make templates…home made fins made of wood, > triple-concave, spiral vee hull bottom twinzers!!!>>> Maybe a 12 step program isn’t a bad idea!!! How true! Finally admitting you have a surfboard design problem is the first step toward sobriety. If so inclined, please confess your sins, that we may all inflict upon you our righteous judgements.
Hey John’ I have had the same thoughts for years. Its hard to LOad up the same energy that George does on his knees, low center of gravity. I still have had a number of flextail boards,one of the best ones was a wilderness that Chris Brock made with Duncan same bottom as your gun,but the tail was like GGs carbon spoons. Also it was only 7’0’'. I know there was about three made one is still in Monticeto ,guy wont sell it . If you have that Surfer mag when GG went to Tahiti on his sailboat Chris Brock is riding one. later KP