Harbour's HPF: An alternative solution to fin wag. *PIC*

I would like to propose an alternative solution to the ‘wag’ problem I encountered in the 9.5" HPF. The diagram should be self explanatory. Of course the following is all a big theoretical exercise, but I believe there’s enough circumstantial evidence to support its serious consideration. Also, I’m pretty much behind the curve on what’s been going in fin theory, so maybe someone has already pursued this idea and has some comments on its functionality. First off, I was interested HPF fin because it had good depth, good rake, and a minimal surface area. The fact that it responded the way it did, did come as a slight surprise. Of course, you all and Rich Harbour made it clear that I failed to fully research whether or not the fin was right for what I had in mind, and I accept that. (But apparently that wasn’t going to stop me.) An alternative solution to the wag problem… If you look at the tail tips of many shark species, you will notice that they have a sort of pliant tip. The tips are not used directly in the generation of forward motion (redirection of flow), in fact when the shark is stroking they often seem to lag behind the main stroke (embodied in the more rigid components of the tail.) A possible benefit of this design (which seems to be common in many fishes that are prone to jerky or quick turns) is that it may play the role of a shock absorber, i.e. to dampen the transient response of the fin when released suddenly from heavily loading. In this case the shark or fish suddenly whipping its tail. They may also be other benefits, such reduced cavitation or a more controlled eddy shedding (energy loss). The proposed design in the diagram was more for illustration purposes. In the end, it would likely have a different form, possibly something more organic in architecture. For example and enclosed series of nylon vertebrae encased in a latex or rubber. Its assumed that the stiffer section, up by the neck and base would remain somewhat stiff. Greenough used flex in his fins (he still may) but his flex axis tends to have the wrong orientation for modern stand-up surfing styles, but then I’ve only seen one or two of his fins, so perhaps somebody more famililar with Greenoughs work might weigh in here. (Dale?) Here the assumption is that the pliant nature of the tip rgion will likely smooth the turn and make transitions far smoother in general. Curiously, there may also be some benefit to extending the idea to thruster fins. I realize that many are now placing small rubber edges on their fins, but here to get the proper effect, the extention would likely be much larger and far more pliable as you move away from the edge. Kevin

I would like to propose an alternative solution to the ‘wag’ problem I > encountered in the 9.5" HPF.>>> The diagram should be self explanatory.>>> Of course the following is all a big theoretical exercise, but I believe > there’s enough circumstantial evidence to support its serious > consideration. Also, Im pretty much behind the curve on whats been going > in fin theory, so maybe someone has already pursued this idea and has some > comments on its functionality.>>> First off, I was interested HPF fin because it had good depth, good rake, > and a minimal surface area. The fact that it responded the way it did, did > come as a slight surprise. Of course, you all and Rich Harbour made it > clear that I failed to fully research whether or not the fin was right for > what I had in mind, and I accept that. (But apparently that wasnt going > to stop me.)>>> An alternative solution to the wag problem…>>> If you look at the tail tips of many shark species, you will notice that > they have a sort of pliant tip. The tips are not used directly in the > generation of forward motion (redirection of flow), in fact when the shark > is stroking they often seem to lag behind the main stroke (embodied in the > more rigid components of the tail.)>>> A possible benefit of this design (which seems to be common in many fishes > that are prone to jerky or quick turns) is that it may play the role of a > shock absorber, i.e. to dampen the transient response of the fin when > released suddenly from heavily loading. In this case the shark or fish > suddenly whipping its tail. They may also be other benefits, such reduced > cavitation or a more controlled eddy shedding (energy loss).>>> The proposed design in the diagram was more for illustration purposes. In > the end, it would likely have a different form, possibly something more > organic in architecture. For example and enclosed series of nylon > vertebrae encased in a latex or rubber. Its assumed that the stiffer > section, up by the neck and base would remain somewhat stiff.>>> Greenough used flex in his fins (he still may) but his flex axis tends to > have the wrong orientation for modern stand-up surfing styles, but then > I’ve only seen one or two of his fins, so perhaps somebody more famililar > with Greenoughs work might weigh in here. (Dale?) Here the assumption is > that the pliant nature of the tip rgion will likely smooth the turn and > make transitions far smoother in general.>>> Curiously, there may also be some benefit to extending the idea to > thruster fins. I realize that many are now placing small rubber edges on > their fins, but here to get the proper effect, the extention would likely > be much larger and far more pliable as you move away from the edge.>>> Kevin are you sure they are true Grenough fins, not one of his templates made by someone else?also, what is wrong with his flex axis,ie it’s location and why no god for stand up surfing?thanks for your response.

are you sure they are true Grenough fins, not one of his templates made by > someone else?also, what is wrong with his flex axis,ie it’s location and > why no god for stand up surfing?thanks for your response. Of course the fin in the illustration is not a Greenough’s, its a Harbour and my modification of a Harbour. As for the Greenough’s I’ve seen, and I did mention that I’ve only seen two, and in those the flex axis tended to be more perpendicular to the board boards bottom and extend throughout the fin in a continuous manner. I assume that the fins that I had seen were in fact Greenough’s, as they were referenced as such. I guess they could have been duplicates, or copies. Here, the fin would be as it now stands, fairly stiff, the flex resulting from the geometry of the shape to a very large degree. However, in the proposed pliant tip region, which could possibly be made of some material like a latex or rubber (similar to the rubber tips used on thruster fins for instance); the pliancy controlled by it geometry (thickness), would offer relatively minimal resistance to flow compared to the main body of the fin, and flex much much more readily. As mentioned, the main purpose of the extended fin tip design would be dampened the wag or the response of the much much stiffer main body. Much the way shock-absorbers in cars dampen the response of the cars springs. Hopefully in the illustration its clear that the pliant tip would tend to track the flow in the tip region, the rest of the fin remaining stiff allowing for the for redirection of flow, i.e. useful for turning. The pliant tip being of no real use in that respect. It is my belief that to turn you need to use a rail or a fin, and rigidity is critical, i.e. stiffness is critical. I was under the impression that Greenough’s fins (admittedly, I’m not even a bad expert on Greenough’s fin design) tended to incorporate flex throughout the fin, both longitudinally and laterally. Which is not the approach here. Here, the highly pliant tip is not likely to assist in turning, as it will conform to just about any flow (virtually no resistance in comparison to the main fin body.) The flex in the highly pliant tip in this case, having the major role of dampening the much more rigid flex response of the main body of the fin. Kevin PS Perhaps (as I mentioned in my original post) somebody can set me straight on Greenough fins. There’s a good chance I have simply failed to understand the dynamics of his fin designs, which I (think) I’ve seen.

Of course the fin in the illustration is not a Greenough’s, its a Harbour > and my modification of a Harbour. As for the Greenough’s I’ve seen, and I > did mention that I’ve only seen two, and in those the flex axis tended to > be more perpendicular to the board boards bottom and extend throughout the > fin in a continuous manner. I assume that the fins that I had seen were in > fact Greenough’s, as they were referenced as such. I guess they could have > been duplicates, or copies.>>> Here, the fin would be as it now stands, fairly stiff, the flex resulting > from the geometry of the shape to a very large degree. However, in the > proposed pliant tip region, which could possibly be made of some material > like a latex or rubber (similar to the rubber tips used on thruster fins > for instance); the pliancy controlled by it geometry (thickness), would > offer relatively minimal resistance to flow compared to the main body of > the fin, and flex much much more readily.>>> As mentioned, the main purpose of the extended fin tip design would be > dampened the wag or the response of the much much stiffer main body. Much > the way shock-absorbers in cars dampen the response of the cars springs.>>> Hopefully in the illustration its clear that the pliant tip would tend to > track the flow in the tip region, the rest of the fin remaining stiff > allowing for the for redirection of flow, i.e. useful for turning. The > pliant tip being of no real use in that respect.>>> It is my belief that to turn you need to use a rail or a fin, and rigidity > is critical, i.e. stiffness is critical. I was under the impression that > Greenough’s fins (admittedly, I’m not even a bad expert on Greenough’s fin > design) tended to incorporate flex throughout the fin, both longitudinally > and laterally. Which is not the approach here. Here, the highly pliant tip > is not likely to assist in turning, as it will conform to just about any > flow (virtually no resistance in comparison to the main fin body.)>>> The flex in the highly pliant tip in this case, having the major role of > dampening the much more rigid flex response of the main body of the fin.>>> Kevin>>> PS>>> Perhaps (as I mentioned in my original post) somebody can set me straight > on Greenough fins. There’s a good chance I have simply failed to > understand the dynamics of his fin designs, which I (think) I’ve seen. Kevin, IMHO, here are some things to consider: In terms of a conventional, hard and stiff surfboard, you are accurate in that the rails and fin(s) are necessary for maintaining most of the control while riding. Maximized penetration is critical. In terms of a hard, but very flexible kneeboard, such as George Greenoughs "Velo", overall rail and bottom contours function in balance with the fin while turning (less emphasis on fin area). Decreased area of penetration, yet increased overall surface contact. In terms of a completely flexible and soft surfmat, the overall pneumatic structure provides a constantly adaptable balance in all aspects of turning, without fins or hard rails. Minimum area of penetration, maximum surface contact. On one side, with hard, inflexible surfcraft, the means of control are primarily dependent upon the fin(s), rails and the rider, much less on the overall design, and very little on an interaction with the wave itself. At the opposite end of the wave riding spectrum, completely flexible, soft and variable pneumatic designs such as surfmats are largely dependent upon an intimate contact with wave itself for control, far less on the rider, and nothing at all on fin(s). As a side note, much of control relates to the actual surface area shared between rider and surfcraft, especially in regards to the riders weight distribution. It can be observed that as the actual area of these control points existing between rider and design decrease, control over increased structural flexibility in such designs also decreases. Fascinating examples of design twists to the previous statements might be the sophisticated (tuned-flexible and light) transitional displacement hull boards of shapers such as Greg Liddle, and also the long, heavy, hard, stiff and finless, 1930s-1950s Hawaiian “Hot Curl” designs. Dale

Kevin, Harbour’s fin is not very close to a Greenough as you have observed. Greenough’s are much stiffer and, more importantly, have a much smaller chord in the foil. Go to “Flex Fins” at www.liddlesurfboards.com where there are several photos and a short discussion on their function. While your there, check out the site for an informative tour of the displacement hull design and performance alternatives. One of the better surfboard sites on the 'net. Newbs

Kevin, Harbour’s fin is not very close to a Greenough as you have > observed. Greenough’s are much stiffer and, more importantly, have a much > smaller chord in the foil. Go to “Flex Fins” at > www.liddlesurfboards.com where there are several photos and a short > discussion on their function. While your there, check out the site for an > informative tour of the displacement hull design and performance > alternatives. One of the better surfboard sites on the 'net. Newbs I agree.Note that George’s fins are like Liddle’s except his leading edges were/are thick and round-sometimes as thick as 1", whereas Greg’s utilize a thin leading edge.Each is correctly balanced and tuned for the craft they were made for.Each has the same flex characters and essentially very similar, if not exact templates.Greg’s hulls are about 1" or less while george’s (Velo)are about 2.5" deep,therefore the difference in leading edge design.

I would like to propose an alternative solution to the ‘wag’ problem I > encountered in the 9.5" HPF.>>> The diagram should be self explanatory.>>> Of course the following is all a big theoretical exercise, but I believe > there’s enough circumstantial evidence to support its serious > consideration. Also, I’m pretty much behind the curve on what’s been going > in fin theory, so maybe someone has already pursued this idea and has some > comments on its functionality.>>> First off, I was interested HPF fin because it had good depth, good rake, > and a minimal surface area. The fact that it responded the way it did, did > come as a slight surprise. Of course, you all and Rich Harbour made it > clear that I failed to fully research whether or not the fin was right for > what I had in mind, and I accept that. (But apparently that wasn’t going > to stop me.)>>> An alternative solution to the wag problem…>>> If you look at the tail tips of many shark species, you will notice that > they have a sort of pliant tip. The tips are not used directly in the > generation of forward motion (redirection of flow), in fact when the shark > is stroking they often seem to lag behind the main stroke (embodied in the > more rigid components of the tail.)>>> A possible benefit of this design (which seems to be common in many fishes > that are prone to jerky or quick turns) is that it may play the role of a > shock absorber, i.e. to dampen the transient response of the fin when > released suddenly from heavily loading. In this case the shark or fish > suddenly whipping its tail. They may also be other benefits, such reduced > cavitation or a more controlled eddy shedding (energy loss).>>> The proposed design in the diagram was more for illustration purposes. In > the end, it would likely have a different form, possibly something more > organic in architecture. For example and enclosed series of nylon > vertebrae encased in a latex or rubber. Its assumed that the stiffer > section, up by the neck and base would remain somewhat stiff.>>> Greenough used flex in his fins (he still may) but his flex axis tends to > have the wrong orientation for modern stand-up surfing styles, but then > I’ve only seen one or two of his fins, so perhaps somebody more famililar > with Greenoughs work might weigh in here. (Dale?) Here the assumption is > that the pliant nature of the tip rgion will likely smooth the turn and > make transitions far smoother in general.>>> Curiously, there may also be some benefit to extending the idea to > thruster fins. I realize that many are now placing small rubber edges on > their fins, but here to get the proper effect, the extention would likely > be much larger and far more pliable as you move away from the edge.>>> Kevin We designed, tested, molded and sold hundreds of thousands of ‘plastic’ skegs in the ‘60s. Many of our advertisements were about how these puppies ‘sprung’ you out of the turn. However, the surfing public caved into preferring rigid fiberglass skegs because THAT’S WHAT THE JERRY LOPEZ’S IN HAWAII were using in the big surf. And rightly so because there can only be so many agenda’s out there and when you’re in TROUBLE, you want DEPENDABILITY under you, not something tricky… with it’s own agenda wobbling you about. However, some years later, and excellent surfer of that era, Tom Lewis experimented with and patented this feature. He should be capitalizing on it now, as a matter of fact since fins like shown are about spring. His claim, is pretty much that they can work like a swim fin. I’m certain they do. What could be done, is to TRY say 2 -4 large skegs like this mounted under a large (say 12’) surfboard. Then stick a guy on there in flat water and have him do the skateboarder’s side to side dance on the set up and see how fast he can get it to propel through the water. The out come could be that the SHORT BOARD builder starts building short boards with a lot more springy skegs. . . like swim fins back there under them because their standard MO is to wiggle that board all over the place, banking off the wall, off the troff, and bouncing air beneath. This could produce considerable extra speed. End

We designed, tested, molded and sold hundreds of thousands of ‘plastic’ > skegs in the ‘60s. Many of our advertisements were about how these puppies > ‘sprung’ you out of the turn. However, the surfing public caved into > preferring rigid fiberglass skegs because THAT’S WHAT THE JERRY LOPEZ’S IN > HAWAII were using in the big surf. And rightly so because there can only > be so many agenda’s out there and when you’re in TROUBLE, you want > DEPENDABILITY under you, not something tricky… with it’s own agenda > wobbling you about.>>> However, some years later, and excellent surfer of that era, Tom Lewis > experimented with and patented this feature. He should be capitalizing on > it now, as a matter of fact since fins like shown are about spring. His > claim, is pretty much that they can work like a swim fin. I’m certain they > do.>>> What could be done, is to TRY say 2 -4 large skegs like this mounted under > a large (say 12’) surfboard. Then stick a guy on there in flat water and > have him do the skateboarder’s side to side dance on the set up and see > how fast he can get it to propel through the water.>>> The out come could be that the SHORT BOARD builder starts building short > boards with a lot more springy skegs. . . like swim fins back there under > them because their standard MO is to wiggle that board all over the place, > banking off the wall, off the troff, and bouncing air beneath. This could > produce considerable extra speed.>>> End Not exactly the application I had in mind, but I can see the connection. I am not a big fan of highly flexible fins. Actually in general, when dealing with stand-up surfing (where the surfer is coupled to the surfboard via the the grace of gravity and through his feet alone) I tend to favor structures which are not likely to deform very much at all (that is, flex should be kept to a minimum.) That is, I agree with the minimal agenda arguement that you suggest above. When I saw the Harbour fin, with its extended rake, good depth and minimal surface area, I just had to give it a shot. I admit that I was hasty, in that I should have seen the wag coming, so to speak. Especially now, given Harbour’s comments – I basically misapplied the fin (my surfboard was too big, and I weigh too much.) My suggestion, was not really to introduce flexibility, but to introduce a local shock absorber in the form of a highly pliant tip, and in the process saving the design features that I did like. And its my belief that its unlikely such a application would introduce another agenda, well hope at least. The application that you’ve suggest, which is actually very interesting, would likely require some fairly extensive modifications, definitely in length and most likely in surface area too. Its definately interesting stuff. … Can you tell me where I can see some of Lewis’ work? Also, was Lewis concerned with the response of his fins to being unloaded (when you get all that loaded energy in the form of a deformation back) as a problem or as a benefit? Kevin

Not exactly the application I had in mind, but I can see the connection.>>> I am not a big fan of highly flexible fins. Actually in general, when > dealing with stand-up surfing (where the surfer is coupled to the > surfboard via the the grace of gravity and through his feet alone) I tend > to favor structures which are not likely to deform very much at all (that > is, flex should be kept to a minimum.) That is, I agree with the minimal > agenda arguement that you suggest above.>>> When I saw the Harbour fin, with its extended rake, good depth and minimal > surface area, I just had to give it a shot. I admit that I was hasty, in > that I should have seen the wag coming, so to speak. Especially now, given > Harbour’s comments – I basically misapplied the fin (my surfboard was too > big, and I weigh too much.)>>> My suggestion, was not really to introduce flexibility, but to introduce a > local shock absorber in the form of a highly pliant tip, and in the > process saving the design features that I did like. And its my belief that > its unlikely such a application would introduce another agenda, well hope > at least.>>> The application that you’ve suggest, which is actually very interesting, > would likely require some fairly extensive modifications, definitely in > length and most likely in surface area too. Its definately interesting > stuff.>>> …>>> Can you tell me where I can see some of Lewis’ work? Also, was Lewis > concerned with the response of his fins to being unloaded (when you get > all that loaded energy in the form of a deformation back) as a problem or > as a benefit?>>> Kevin my apologies in advance. i seldom visit swaylocks as much anymore cause ive all too often been surprised and disappointed by ongoing comments and misnomers concerning aspects relating to flex in fins and surfboards that were originally designed, tested, proven and documented over 30 years ago by george greenough. ever see his films or watch him surf? stop and consider how he successfully got that inside the barrel footage- often in macking overhead waves- if he was using "something tricky" and undependable. how many other designers, shapers, visionaries have EVER backed up their words with design, creation, invention, performance, filmmaking personal documentation like that???? NO ONE has ever put it ALL together like Greenough. how people can say theyve progressed beyond all that old stuff- yet obviously not have a clue about what greenoughs proven concepts were and what he did with them- is incredibly ignorant or arrogant. or both. what ripped performance surfing wide open in the late 1960s werent stiff fins and longboard designs. like one damn fine magician Greenough got it right, then simply passed everyone by. over 30 years later people who should know better are still trying to figure out WHAT he did. hello? the lights are on, but no one is home??? or in the case of this thread- publically demonstrating they obviously failed to comprehend the core of that entire revolution. fin and surfboard design are held back because those people who dont clearly understand and have an inspired appreciation for the brightest moments of surfings past. why? looks to me the status quo is way too busy “building surfboards” to notice theyre only putting a polish on the repeat sales of orchestrated mediocrity. the heart and soul of real surfing has absolutely NOTHING to do with patent rights, the latest issue of your favorite surf mag, sales trends, clothing and accessories or old advertising gimmicks under new names. never be seduced and confused by the love of building your boards with the love of experiencing them. to those of you who like to brandish queries in this forum- dont forget that the asking of questions isn`t nearly as important as personally discovering the answers. shoots.

my apologies in advance. i seldom visit swaylocks as much anymore cause > ive all too often been surprised and disappointed by ongoing comments and > misnomers concerning aspects relating to flex in fins and surfboards that > were originally designed, tested, proven and documented over 30 years ago > by george greenough. ever see his films or watch him surf? stop and > consider how he successfully got that inside the barrel footage- often in > macking overhead waves- if he was using "something tricky" and > undependable. how many other designers, shapers, visionaries have EVER > backed up their words with design, creation, invention, performance, > filmmaking personal documentation like that???? NO ONE has ever put it ALL > together like Greenough. how people can say theyve progressed beyond all > that old stuff- yet obviously not have a clue about what greenoughs > proven concepts were and what he did with them- is incredibly ignorant or > arrogant. or both.>>> what ripped performance surfing wide open in the late 1960s werent stiff > fins and longboard designs. like one damn fine magician Greenough got it > right, then simply passed everyone by. over 30 years later people who > should know better are still trying to figure out WHAT he did. hello? the > lights are on, but no one is home??? or in the case of this thread- > publically demonstrating they obviously failed to comprehend the core of > that entire revolution. fin and surfboard design are held back because > those people who dont clearly understand and have an inspired > appreciation for the brightest moments of surfings past. why? looks to me > the status quo is way too busy “building surfboards” to notice > theyre only putting a polish on the repeat sales of orchestrated > mediocrity.>>> the heart and soul of real surfing has absolutely NOTHING to do with > patent rights, the latest issue of your favorite surf mag, sales trends, > clothing and accessories or old advertising gimmicks under new names. > never be seduced and confused by the love of building your boards with the > love of experiencing them.>>> to those of you who like to brandish queries in this forum- dont forget > that the asking of questions isn`t nearly as important as personally > discovering the answers.>>> shoots. Amen.Who or what has come down the pike since that has revolutionized surfing as completely as Mr. Greenough.He was light years ahead of them then and still is.

My recent quest for boards without foam is such a mind opener… Before I would get hung up on dimensions, etc…now I’m looking at ordinary materials and building boards with them… I’m into the FEELING of hollow boards with different skins and rails under me, and I haven’t been this stoked in a long, long time…

Below is a pictorial outline of how I propose to build the extended tip fin (see prior post for description and possible function.) I will keep the main body of the fin to 36 sheets of 6 oz. cloth, the progressively more pliant areas are respectively 10, 6 and 2 sheets see diagram. In the hopes of minimizing the amount of glass I’ll have to sand away, I used the wax paper trick, (how that might work is hopefully clear from the diagram.) The pliant tip will be made of silicone, as indicated in the diagram. The pliant tip extension mold being made from balsa wood (smeared with Vaseline or paraffin, varnish has been suggested.) Dimensions? My initial feeling is to make a stupidly long silicone tip (2 foot or more?) and then start to cut it back during experimentation. Hopefully, I will be able to cut it off, the whole silicone region, and re-mold when I have found something I think is optimal… if I actually find that this thing works. I’m not really worried about durability at this point, as long at it lasts for a session or two. I am open for suggestions on the dimensions of the fin in general, base, neck, depth, curves, length of pliant tip whatever. (See next post for Harbour’s 9.5" HPF dimensions.) Also, in the diagram, I use glass layer as a way to control flex, this is of course nothing new, but if anybody has any experience in this area and wants to throw in their two cents, please do! I start construction tomorrow, but its unlikely I’ll cut the template until Sunday or Monday. If it actually works, (that is, I find something that actually works) then maybe we can pass it around to all who are interested to give it a try. Kevin

Here are Harbour’s dimensions.

my apologies in advance. i seldom visit swaylocks as much anymore cause > ive all too often been surprised and disappointed by ongoing comments and > misnomers concerning aspects relating to flex in fins and surfboards that > were originally designed, tested, proven and documented over 30 years ago > by george greenough. ever see his films or watch him surf? stop and > consider how he successfully got that inside the barrel footage- often in > macking overhead waves- if he was using "something tricky" and > undependable. how many other designers, shapers, visionaries have EVER > backed up their words with design, creation, invention, performance, > filmmaking personal documentation like that???? NO ONE has ever put it ALL > together like Greenough. how people can say theyve progressed beyond all > that old stuff- yet obviously not have a clue about what greenoughs > proven concepts were and what he did with them- is incredibly ignorant or > arrogant. or both.>>> what ripped performance surfing wide open in the late 1960s werent stiff > fins and longboard designs. like one damn fine magician Greenough got it > right, then simply passed everyone by. over 30 years later people who > should know better are still trying to figure out WHAT he did. hello? the > lights are on, but no one is home??? or in the case of this thread- > publically demonstrating they obviously failed to comprehend the core of > that entire revolution. fin and surfboard design are held back because > those people who dont clearly understand and have an inspired > appreciation for the brightest moments of surfings past. why? looks to me > the status quo is way too busy “building surfboards” to notice > theyre only putting a polish on the repeat sales of orchestrated > mediocrity.>>> the heart and soul of real surfing has absolutely NOTHING to do with > patent rights, the latest issue of your favorite surf mag, sales trends, > clothing and accessories or old advertising gimmicks under new names. > never be seduced and confused by the love of building your boards with the > love of experiencing them.>>> to those of you who like to brandish queries in this forum- dont forget > that the asking of questions isn`t nearly as important as personally > discovering the answers.>>> shoots. Ron I do not doubt Greenough’s great innovative spirit. Your comments make it clear that perhaps you understand, or appreciate Greenough’s philosophy and approach. So, if you have a mind to, maybe you can help me understand some of Greenough’s applications as they relate to a particular form of surfing - stand-up loosely coupled (via gravity and through the feet) surfing. Of what I know of Greenough (and I admit my ignorance), he surfed devices which allowed him to bring far more of his body to bare in controlling his surfboard (kneeboard.) Through his innovative flexible designs, he was able to utilize shoulders, arms, abdomen, hips etc… each acting independently, adjusting various control surfaces, to maximize their efficiency and effect. But this is quite unlike stand-up surfing, were the surfer is limited to what he can translate to his control surfaces through his feet. Flex made sense the way Greenough surfs (or surfed) – he was able to control to by bringing different body parts to bare on the device. One could surely argue that flex is this case was a way of allowing the surfer to create (almost on the fly) different control surfaces, the flex also allowing him to blend them so as to operate as a whole. But if you’ve only got to points of contact, in my case each approximately 4 inches by 9 inches, how does one control more than (at best) two control surfaces? In my opinion the approach to (stand-up surfing surfboard) design surely has to reflect these limitations. Incorporate flex if you can, but what good is flex if it reacts passively, that is it can not be controlled. Hold something flexible in a flow and it passively conforms to the forces that be, at least the best it can, adjusting so as to offer minimal resistance. But surfing is about exacting or translating wave energy, not accommodating it – Kelp accommodates. So unless one is able to bring flex under control so as make the best use of the flexible surface (as Greenough did) I am inclined to think that flex, passive flex has little application in stand-up surfing – rigid or stiff, would appear to be the more appropriate paradigm for stand-up surfing. Flexible Fins My feelings on flexible fins are basically the same. I would think one would want stiff fins to be able to reliably redirect flow, at will. Again, fins which accommodate flow would be of little use in this respect. In my suggested design (and apparently it may not be mine, as it has been suggested that Tom Lewis, possibly Greenough worked with such an application) is to place a totally pliant tip structure on a rigid fin, which, the tip that is, will purposely accommodate flow, its role not being that of a control surface, but hopefully that of a ‘shock absorber’, see initial postings. Flex covers a lot of ground. I’m not at all sure that the kind of pliant accommodating flex that I am suggesting be used here is at all like the ‘flex’ that Greenough, or possibly Lewis used. My extended fin tip, will be very easily deformed, that is it will require relatively little energy to deform, and upon being unloaded return equally little energy. Help me understand Greenough, and Tom Lewis’ application as they apply to stand-up loosely coupled surfing. (Also, if you are aware of anyone who has already created a similar application (as the one suggested in this post) please let us know, and maybe let us know if it worked, under what conditions did it work, is it still being used, who can we look to for more about it, etc…) Thanks, Kevin

In my opinion the approach to (stand-up surfing surfboard) design surely > has to reflect these limitations. Incorporate flex if you can, but what > good is flex if it reacts passively, that is it can not be controlled. Does a none flexible surfboard react passivly? Can’t it be controlled? Why would flex be any different? regards, Håvard

Does a none flexible surfboard react passivly? Can’t it be controlled?>>> Why would flex be any different?>>> regards,>>> Håvard First off, I’m assuming we are talking about stand-up loosely coupled surfing (surfer is attached to the surfboard via gravity and through his feet.) Flex is a property. To say something is non-flexible is also a property, but it also means that there’s nothing there to react passively or actively? There are other properties of surfboards such as surface area, foil, etc. which the shaper puts into the board, these are fixed, but can nevertheless be brought on and off line to a degree and be expected to function in a reliable way, through the actions of the surfer. A flexible surfboard will react to the forces that be (from the flow of water, etc.), changing its shape or form to an extent dependent on the prevailing forces. In my opinion this is not desirable, for it is in the ability to present a control surface in a given reliable manner to the flow which allows the surfer to ‘surf.’ Rigid control surfaces make surfboards go, so to speak - they redirect water flow. It is conceivable to have a flexible surfboard, but in my opinion it will require a higher degree of coupling between surfer and surfboard. This additional coupling would allow the surfer greater control over how the flex is bought on line (and off line.) Which brings me back to Greenough’s designs. One thing which rarely seems to be discussed is that Greenough’s flexible structures are not stand-up loosely coupled surfboards. They work because the surfer is able to use almost all of his body to control his surfboards control surfaces, i.e. his kneeing or laying prone. The flex in this case is a way of allowing the surfer to create different control surfaces on the fly - they are not reacting passively! The surfer remains in full control, and with the additional control surfaces can potentially do a lot more. Well almost, I don’t believe its true for his fin designs, at least the ones I’ve seen. A fin which flexes when presented with a flow is limited in terms of its ability to redirect flow, and if its not redirecting flow what is it doing? In my opinion its telling you (the surfer) what to do next, that is the surfer must now ‘surf the flex.’ You may find this desirable, I don’t. If you like it, go for it! (By the way, the same thing could be said about a rigid surfboard, or a rigid fin! So, it really is a matter of personal preference.) My extended pliant tip fin, if it works will not be redirecting flow but functioning as a shock absorber. Kevin

First off, I’m assuming we are talking about stand-up loosely coupled > surfing (surfer is attached to the surfboard via gravity and through his > feet.)>>> Flex is a property. To say something is non-flexible is also a property, > but it also means that there’s nothing there to react passively or > actively?>>> There are other properties of surfboards such as surface area, foil, etc. > which the shaper puts into the board, these are fixed, but can > nevertheless be brought on and off line to a degree and be expected to > function in a reliable way, through the actions of the surfer.>>> A flexible surfboard will react to the forces that be (from the flow of > water, etc.), changing its shape or form to an extent dependent on the > prevailing forces. In my opinion this is not desirable, for it is in the > ability to present a control surface in a given reliable manner to the > flow which allows the surfer to ‘surf.’ Rigid control surfaces make > surfboards go, so to speak - they redirect water flow.>>> It is conceivable to have a flexible surfboard, but in my opinion it will > require a higher degree of coupling between surfer and surfboard. This > additional coupling would allow the surfer greater control over how the > flex is bought on line (and off line.)>>> Which brings me back to Greenough’s designs. One thing which rarely seems > to be discussed is that Greenough’s flexible structures are not stand-up > loosely coupled surfboards. They work because the surfer is able to use > almost all of his body to control his surfboards control surfaces, i.e. > his kneeing or laying prone. The flex in this case is a way of allowing > the surfer to create different control surfaces on the fly - they are not > reacting passively! The surfer remains in full control, and with the > additional control surfaces can potentially do a lot more. Well almost, I > don’t believe its true for his fin designs, at least the ones I’ve seen.>>> A fin which flexes when presented with a flow is limited in terms of its > ability to redirect flow, and if its not redirecting flow what is it > doing? In my opinion its telling you (the surfer) what to do next, that is > the surfer must now ‘surf the flex.’ You may find this desirable, I don’t. > If you like it, go for it! (By the way, the same thing could be said about > a rigid surfboard, or a rigid fin! So, it really is a matter of personal > preference.)>>> My extended pliant tip fin, if it works will not be redirecting flow but > functioning as a shock absorber.>>> Kevin History demonstrates that all mannner of devices can be used for surfing have the potential to “work”… but some will tend to function better, or more efficiently. Athletically “forcing” a design to perform is a topic for another thread. The flex that works best in surfcraft is the same that you will discover to one degree or another, in many other types sports equipment (tennis racquets, pole vaulting poles, skis/snowboards, archery bows, skateboard decks, diving boards, basket/soccer balls, golf clubs, etc.): a flex that has excellent resiliency, memory, resonance and kicks back quick and hard after being stressed. Only certain materials and methods of construction/structure will allow these characteristics, especially without degrading from structural fatigue over long term use. In contrast, flex that is less responsive, with muted resonance, memory and a tendancy to absorb sensation, is the worst. As for the question of a rider using flex in surfing, a thin analogy can be drawn between those who have learned how to exploit the function of a trampoline, and those who havent. Assuming the equipment is tuned properly, developing a keen sense for exactly the right moment to weight and unweight is elementary to success... and easily observable. In terms of surfing, there are certain kinds of waves, and parts of those waves, that cannot be fully experienced and appreciated without a surfcraft that offers a measure of tuned flex. In conclusion, theres more going on in many waves than a rigid surfcraft can effectively tap into… far more! Anyone who has experienced good waves, with something that flexes properly, is soon surprised and delighted by their discovery of this other world of sensation and performance. Its there and its real. Dale

History demonstrates that all mannner of devices can be used for surfing > have the potential to “work”… but some will tend to function > better, or more efficiently. Athletically “forcing” a design to > perform is a topic for another thread.>>> The flex that works best in surfcraft is the same that you will discover > to one degree or another, in many other types sports equipment (tennis > racquets, pole vaulting poles, skis/snowboards, archery bows, skateboard > decks, diving boards, basket/soccer balls, golf clubs, etc.): a flex that > has excellent resiliency, memory, resonance and kicks back quick and hard > after being stressed. Only certain materials and methods of > construction/structure will allow these characteristics, especially > without degrading from structural fatigue over long term use. In contrast, > flex that is less responsive, with muted resonance, memory and a tendancy > to absorb sensation, is the worst.>>> As for the question of a rider using flex in surfing, a thin analogy can > be drawn between those who have learned how to exploit the function of a > trampoline, and those who havent. Assuming the equipment is tuned > properly, developing a keen sense for exactly the right moment to weight > and unweight is elementary to success... and easily observable. In terms > of surfing, there are certain kinds of waves, and parts of those waves, > that cannot be fully experienced and appreciated without a surfcraft that > offers a measure of tuned flex.>>> In conclusion, theres more going on in many waves than a rigid surfcraft > can effectively tap into… far more! Anyone who has experienced good > waves, with something that flexes properly, is soon surprised and > delighted by their discovery of this other world of sensation and > performance. Its there and its real.>>> Dale Dale, First off a question. Has anyone done something with a suit, sort of a surfmat you climb into? Maybe strategically placed inflatable panels on the chest, abdomin, arms legs,etc. Not much in term of presence, but enough to allow the surfer to bring any given panel (control surface) on line, or off at will. I hate to make the analogy, but in my mind the fellow using such a suit could be likened to one of those transformer toys that were popular a while back. I’m serious, do you know if it has been done? On your comments… I don’t doubt the benefit of flex. What is becoming clear to me is that I may be using the term differently than many of the others who have made (seemingly) less negative comments about its role in stand-up loosely coupled surfing. Perhaps its time I made it clear what I’m refering to, and maybe others will hopefully weigh in on the matter - set a context if you like. I’ll start a thread. As for good waves, well,… you’ve hit my Achilles heel. I live in a land of Fire and Ice, its either real good or real bad. Surfers in my little corner of the globe, are very aggressive, not bullies, but aggressive in that they tend to make the most of the precious little they get (I’m not refering to the summer or weekend crowd.) I don’t wish to imply that there’s something heroic about having a lot of shitty surf to deal with, but it does have a way of helping you cut through the bullshit in terms of equipement. Admittedly, sometimes your curiousity gets the best of you, and you buy the latest model board from some maker from someplace far more fortunate in terms surf quality, figuring ‘they must know what their doing’, but after one or two session of having your senses beaten back into you, you climb back onto to something you know works. So, in a way I disagree, I think ‘less’ can wind up making you more realistic and efficient. Good waves? I think we had one of those a while back… I think?

History demonstrates that all mannner of devices can be used for surfing > have the potential to “work”… but some will tend to function > better, or more efficiently. Athletically “forcing” a design to > perform is a topic for another thread.>>> The flex that works best in surfcraft is the same that you will discover > to one degree or another, in many other types sports equipment (tennis > racquets, pole vaulting poles, skis/snowboards, archery bows, skateboard > decks, diving boards, basket/soccer balls, golf clubs, etc.): a flex that > has excellent resiliency, memory, resonance and kicks back quick and hard > after being stressed. Only certain materials and methods of > construction/structure will allow these characteristics, especially > without degrading from structural fatigue over long term use. In contrast, > flex that is less responsive, with muted resonance, memory and a tendancy > to absorb sensation, is the worst.>>> As for the question of a rider using flex in surfing, a thin analogy can > be drawn between those who have learned how to exploit the function of a > trampoline, and those who havent. Assuming the equipment is tuned > properly, developing a keen sense for exactly the right moment to weight > and unweight is elementary to success... and easily observable. In terms > of surfing, there are certain kinds of waves, and parts of those waves, > that cannot be fully experienced and appreciated without a surfcraft that > offers a measure of tuned flex.>>> In conclusion, theres more going on in many waves than a rigid surfcraft > can effectively tap into… far more! Anyone who has experienced good > waves, with something that flexes properly, is soon surprised and > delighted by their discovery of this other world of sensation and > performance. Its there and its real.>>> Dale Dale: well said my friend-perfect analogy using the trampoline.flex on!

“Has anyone done something with a suit, sort of a surfmat you climb into? Maybe strategically placed inflatable panels on the chest, abdomin, arms legs, etc. Not much in term of presence, but enough to allow the surfer to bring any given panel (control surface) on line, or off at will?” Kevin, youre describing something that Ive drawn scale diagrams of, off and on for nearly 30 years… hey, remember the “Michelin Man” logo character? Something like that would have to be close to the ultimate in underground surfwear! But seriously, the modern surfmat as it currently exists, has evolved to the point of being nearly ideal in a number of functional design elements that are normally interpreted as compromises in conventional equipment. Plus, its an exercise in futility to argue with the mystifying, wide range performance of such a deceptively simple form of sophistication. IMHO, the most relevant and personally satisfying direction you can go with your surfing, is to find out what works for YOU, and in the waves you ride most frequently.... and unless you travel to exotic locales regularly, or live at such places, to hell with boards for Burleigh Heads, G-land and Pipeline. No matter whether your area is often plagued with bad surf, or blessed with good, I say design, build and discover your own pathway to understanding and pleasure. Although I realize its not for everybody, I firmly believe that people who haven`t shaped and glassed at least one of their own boards, and tried using different fins, are totally missing out on some very significant chapters in their lives as surfers. Dale