FYI There’s an interesting article in this month’s Australian Surfing life about Salomon and FCS latest research activities. As usual light on detail but there is some preliminary results from FCS testing at the Australian Maritime Hydrodynamics Research Centre in Tasmania. Cavitation is witnessed on fins in high speed water flows, with best performer of the FCS range being the K-fin. Article states that so far foil and total area have the most effect with materials the third most significant factor. Salomon have been measuring interaction between rider and board using preasure measuring pads in booties. Rider wears a small device that records data captured. Not sure what the use of this would be, but the article shows some impressive looking graphs and charts. There’s a bit more about Salomon’s s-core, I get the impression that the s-core has introduced more variables into the mix than people know what to do with. Could be years before anything really ground breaking emerges, if at all. And apparantly Salomon and FCS have been attempting to integrate fin and board design, but I don’t think that’s new. Cheers Stephen
Nice to hear science being applied, but what are they studying? Existing fins, any prototypes being examined? What about the “strength” of board/fin connection. (I know a ding repair guy who’s kept in business by FCS). Are they still calling it cavitation? Who’s paying for this? Is it science or marketing? Rob Olliges
Sounds like marketing… Cavitation seems to run in a similar category as Bigfoot and the Lockness Monster, there’s more unconfirmed sightings than anything substantial. For a surfboard fin I would expect to see some extremely fast velocities, ones that have nothing to do with surfing, in order to ‘boil’ the water around it. It’s unlikely that’s what they saw – and if they weren’t using some really expensive, high speed, high magnification, high quality cameras, then I know that’s not what they saw, because that’s what it takes to see it. More often than not, it’s just pulling dissolved oxygen out of the water… Not that I’m against the testing, I think that’s great, but as and Engineer I know what marketing can do with preliminary data – draw their own conclusions, use some big words, and spice it up with colorful (but misleading) graphs and pictures.
NO these guys are not markeying / this is science didnt we hear institute abd Labrutorie in there somewhere…I for one will pay handsomely for the industrial espionage to steal the information and sell it to the next chinese / lybian cartel going into molding production …foil and that other stuff wow who woulda ever thunk that…thank god for sink tanks…arent those the cavitations there talking about? I’ve been pleased to hold a GREG LIDDLE fin in hand for a coupla days now now thats lab work I tell ya the guy he loaned it to was so intimidated he couldnt try it this is an experimental thread ongoing from the greenough 4-d days dont fund any one but these guys this is pure science and technology applied they are denied royalties while corp=marketing interests fein insight by rehashing stuff figured out years ago that simply validates these former truths demonstrated in daily use ! kudos to the lab isti tute guys? hhccwack patooey us guys here on the porch knew that an you just feel that fin an you know somthin’s up and its scary enough for the common regular guy to be leary [not to be confused with the psychic adventurer arressted in texas] I could be wrong but I heard tha t a large fin manufacturer has set their sights on actually paying to use designs from the guys that actually refined them and not just use their names to market cheap jewelry I bave been wrong before so dont Quote me just put small denominations of cash or other negotiables into envelopes and send donations to your neighborhood think tank scientists…if you dont have one send it to Liddle or Paul Gross or the Halycon guy and bypass the beaureaocratix luncheons where they plot to capture the pure science on a napkin and spin it into gold with the aid of a pattent lawyer …morning rave complete I hope I Didnt annoy you … ambrose … after thought ;;; with subsidy these guys might not have to take busboy jobs .or supermarket convience clerk or advertizing editor or president or california dictator
I’m always impressed when anyone tries to actually quantitate data on surfboard design/materials. Patagonia did some stuff with material and now it sounds like these folks are trying to evaluate design. It sure beats some wild eyed kid (who just finished a brain wash/dope smoking session with his shaping guru)spouting rubbish about this or that gimmick making his boards SOOO much faster, turn SOOO much harder, last SOOO much longer, etc.
…Data collecting,tanks,etc are great,don’t get me wrong but… …I go by with what goes on under my feet,don’t you?Herb
Many of the eastern innovators (that’s Florida to you and me) have long felt that the mainstream manufacturers have ripped them off. How? What’s the conspiracy? It’s known as Surf Expo. Patagonia experimenting with materials? Probably, but they also hire epoxy gurus to lead them to the light. Rob Olliges http://heartsforholeman.org/
Howzit Rob, The Austrailian Gov. gave FCS a 2 million dollar grant for R and D 2 years ago. Wouldn’t it be nice if our Federal Gov. would do the same. I wonder if anyone has ever applied for a U.S. Fed. grant for the same, Might be worth a try when you consider some of the things they do give grants for. Aloha, Kokua
Howzit Rook, My older brother owned and raced flat bottom race boats and that was how I learned what cavitation was ( cavitation plate ). It’s real and not a myth like big foot or lochness monster. I won’t pretend to know the scientific aspects but I do know that when a boat cavitates it loses power and you can’t steer it. In the world of surfboards this translates to ineffiencent performance of the fins since there’s less resistance when the water is full of air bubbles. Aloha, Kokua
Hey Kokua: I won’t claim expert knowledge in the field, I specialized in Mechanical Systems, but have studied my fair share of fluid mechanics, and also I now work as a Bio-mechanical engineer, designing implantable centrifugal blood pumps – one of the first factors you consider in such a project, is cavitation, because it is such an extreme condition, it makes a nice “glass roof” to design under. Cavitation is the act of artificially lowering the pressure at some point in a system to the vapor pressure of the working fluid. In other words (and I’m not trying to insult anyone, just explaining in plain English), you know how when you go up to the mountains water boils quicker – so you have to cook your food longer – because its not as hot… because the pressure is lower. Keep lowering the pressure, a lot, and sooner or later, water will boil at room temperature – Cavitation. It’s very much a reality in motorboats, but not because of the speed of the boat, it’s the speed of the impellar. This creates small localized regions of very low pressure where cavitation can occur. I mention Bigfoot because of how small and quick this happens. You can’t see cavitation with the naked eye, remember that once the pressure returns to anywhere above vapor pressure the gas will change back into a liquid. I just hear the term improperly thrown around at work all the time, so it caught my eye in this thread. That being said, I think my earlier post came out too negative… I of course do support any type of effort to qualitatively or quantitatively analyze surfboards, and I would love to see the results of what was done. It’s just that results can be misinterpreted by the general public, or even the scientist. Also, just because you have a laboratory and some geeky looking guys in labcoats, doesn’t mean that your running scientifically significant studies… even the best of scientists have let there feelings skew their better judgment. And when it all comes down to it, its as Herb said, “it’s all about what’s under your feet” Cheers, and happy experimenting
WHAT?
I’m an engineer. You can’t measure surfing.
that Patagonia rip off was disgusting. One guy has led the way in epoxy for surfboards. ANd he’s too noble to make a fuss about it.
Marketing sprayed with a light coating of scientific gloss.
Had another look at the article - The cavitation chamber they use is one of four in the world. It’s basically an enclosed vertical column of water that flows down at high speed and is pumped up another enclosed column to the top. There is no air in the enclosure and researchers can view the action of objects in the flow through a big window and record data from a series of sensors in a plate that the object is attached to. There is a picture in the article of cavitation occuring, it looks kind of like smoke gathering around and behind the fin. I’m not sure what how this relates to what happens to a fin when your are riding a wave. The experiment would be analogous to being towed across a dead calm lake. When you are surfing you’ve got the energy of the swell, the movement of water up the face and your own motion relative to those two forces effecting the board. It seems to me that the hydrodynamic environment is way more complicated than what boats encounter. My take on the research thing is, first find a University that undertakes the kind of research applicable to your need. Then get them to write the grant proposal. Universities are experts at sniffing out and applying for any grant money going, they are also open to ideas for research from business. The other factor is Government, find a state that is having an election and see what industry support they have built into their promises. If they’ve got any money, a couple of months into their term they’ll start rolling out the grant conditions.
Doesnt matter hollow boards arent the answer anyway. Juat ask Tom Blake
Depends on the question. Current world number 3 - Kieren Perrow rides one.
Kiran rides those Because hes paid to By Saloman.I saw Slater looking pretty skitish on his last year in France, And Surfed a couple hours with Frederick and Micky on theirs last week as well (isnt Micky riding the one Slater gave back?). They just dont look right to me…Time will tell. By the way, Kieran is #3 because he charges in the big stuff and has really good wave selection and a bit of luck. His on wave performance is subpar to his contemperarys. Great guy though.
Try as you might rook, they just didn’t get it. So here’s my shot at debunking the term “cavitation.” Cavitation doesn’t exist in surfboards or surfboard fins. It only exists in props, high speed hydrofoils, turbines and pumps. And yet this “cavitation” has been repeated to me as the cause of spin out for over 35 years. Fins spin out because they either stall or ventilate. Stall happens because the angle of incidence (angle of the water as it meets the leading edge of the fin) becomes to high for the attached water flow on the low pressure side of the fin to remain attached. Ventilation happens when surface air is sucked down the low pressure side of the fin interrupting attached flow. The low pressure side of the fin is 2/3 its power. In other words the suction side is twice as powerful as the pressure on the high side of the fin. Fins rarely stall. They ventilate 99% of the time. Cavitation doesn’t happen until pressure on the high pressure side, or on the low pressure side near the leading or trailing edge, raises to near vapor pressure of the liquid which vaporizes the liquid. The air pockets or cavities formed by this vaporization are cavitation. This can also happen around tip vortices on props. At the speeds we are capable of going it is doubtful that this could ever happen. So we need to amend our vocabulary to properly identify spin out as ventilation. The football, S, Fence and Boomerang fins discussed on this site were all designed to eliminate ventilation by using either forward rake or “fences” built into the fins to reduce traveling bubble ventilation. These designs were all eventually discarded from sailboards when it was found that proper foil could better eliminate ventilation without the disadvantage of excessive drag caused by these early fins.
Flawlessly stated Greg, about the fins. Could you give your input on my negatives towards the Salomans and holow boards in general. I am sure it will be interesting to hear.