I was at Kazuma’s last week buying a G10 quad fin set for my Phillet and they only sell asymmetric’s for the front and symmetric’s (center fins) for the rear for quad directional kite boards (which they also manufacture). All quad directional kite boards I have ridden use 4 asymmetric’s. Kazuma’s reasoning is that the asymmetric’s (front) are for turning and symmetric’s (rear) are for drive. Different purpose equals very different foil shapes. Are the windsurfer quad setups Kazuma or 4 asymmetric’s? Any thoughts? PS I am going to switch to the Kazuma’’s and see whutz’up regardless.

On my Quatro 85 Quad the smaller fronts are assym and the larger centers are syms. Fairly certain this is the most common stock setup for wind boards.

Their reasoning is sound, based around current technology. Front ones you want assymetric lift to "grip" and provide maximum lift into inside turn radius and the smaller size allows for lift/drag tradeoff. Rear ones, you want to have equal lift on both sides of centerline and minimize lift/drag ratios and get lift from angle of attack adjustments.

Be interesting to see what one could do with lift field interaction on the rear two! God I hope to make some money, retire, move to Maui, and play with this (in this lifetime.) No particular reason why rear foils "should" be symmetric. Would also be interesting to see whether any foil in nature is in fact symmetric when dynamic. Active foil shaping is totally possible with certain composites - scale, strength, and durability may be the controlling factors though. Hmmmm Ideas??

For straightline speed when the board is flat, wouldn't larger rear assym fins cause increased drag from the opposing forces and less laminar flow? I am just thinking of dual ruddered sail boats here, which typically are syms (in my expeirence).

Granted once you started turning the board they would probably be better, but would the loss of speed be worth it.

Nanmoo - I am thinking that since from the fin's perspective you are almost never going "straight" - straightline speed still requires certain angle of attack and fin lift to balance what's driving/happening at the sail and the interfaces, then future of fins in quads/twins is likely in assymetrical (not implying flat on one face - that's mostly for cheaper manufacturing) and also out-of-plane fins (curved/twisted/etc.) Be fun ideas to play with, until single fin boards come back in style.

Geoffy wrote:Be fun ideas to play with, until single fin boards come back in style.

I must say I had a blast playing on my single fin OES the other day, almost as good as a quad but not quite the same. Yet I would never have ridden it like that if I had not had a quad for a while now. It seems to open the door to a whole new approach to riding....at least it did for me. Now that I have figured some stuff out the easy way, I can reproduce most of it on the single... So, still stoked on the quad...and you never get the cafeteria slides so fun with a longer fin, I am sure....but even that may change

My favourite subject. Just picked up, in fact had to back order a set of quad FCS fins. That gives you the 11cm asym and 10 sym. Also picked up a set of 9 sym. Smaller ones were sym as they normally are on the surfboard set up as Kayakdoc noted. I am using 11cm asym FCS on the Evil Quint 80 conversion for the smaller front fins. I wanted to try smaller front fins which is why I ordered them. It is hard to find smaller that are not sym. Negligent in not swapping in the 11cm sym FCS type that my Starboard quad 71 l came with to run a comparison. In my defence I have also been testing the thruster set up. In my opinion it is difficult to compare unless you do it on the same day and in the same conditions. So when it's cold there is not much motivation to swap syms for asyms. The 11 cm asyms do work great on the 80 . Most the chat on the Brit Boards website for conversions confirms the asyms in the front with toe in. I thought no windsurf manufacturers have gone to asyms in the front, but Nanmoo says that his are. Will report back when I test the syms if I can notice a difference. When I read back the above it sounds like a bunch of gobbledegoop but I think it does improve my awareness of my sailing to try different set ups and then try and differentiate in my own mind. I also agree with Kus that I think my sailing has changed/improved with the single fin from my experience with the quad and thruster. I can definitely crank turns on 105 better than I used to or at least I think I can so I can

Pfffttt there is a chance I may have been thinking of my SUP fins when I wrote this... on second thought all the quad 85 fins might be syms

nanmoo wrote:Pfffttt there is a chance I may have been thinking of my SUP fins when I wrote this... on second thought all the quad 85 fins might be syms

Most windsurfer front and rear quad fins (Including the Goya and Quatro production ones so far) are symmetrical. Lots of guys are experimenting with custom or home made assym front profiles and toe angles. It's early days yet for windsurfer quad set ups.

All great comments. Regarding fin build, design and placement I just took a look at the new set of race fins (42 cm front (asyms-very subtle), 38 cm rear (sym) = monsters!) I received from Paolo Rista for my Aguera race board. The layers of G10 mill as if they are wood. The pattern of the emerging glass layers indicates fin thickness and each fin mirrors its counterpart. So the construction aspects of these fin designs appears to be flawless...works of art. Moving onto design I was privy to some of the 2 month testing dynamic between Paolo and Adam Koch. Paolo was pushing for hydrodynamic performance whereas Adam needed efficiency....and by efficiency I mean that Adam needed the fins to perform, but not at the cost of rider fatigue. This was a great seesaw to watch as designer and performer slowly extracted a realized collective vision. I watched as they discussed moving a 45cm fin less than 1/64” by which to reduce bow movement at high speed. Paolo than produced these new fins for the next days testing. This type of interaction took place almost everyday for two months. I am interested in seeing the effect on the World Cup circuit this year. I know that Johnny Heineken is working with Dennis Parton at Tectonics, although their interactions are text and voice only. I am under the impression they have not met. I mention this because I am interested to see how fin design will emerge and whether technological input is enough or tactile interconnectivity is required. I might label this the psychological aspect of fin design. Regardless it is fun to be a fly on the wall as the emergence of kite fin design cuts upwind to the Brazilian Olympics. After Notes: Paolo’s SUP fin designs won the 2011 Battle of the Paddle at Dana Point (a big deal for SUPer’s). His work on kite board (surfboard) directional fin designs for race use contributed to impressive wins in this class this past summer. Dennis Parton at Tectonics has been designing windsurf fins since the time of Noah. Fins appear to be a big deal and although I believe kite board demands are different than windsurfers I wonder if we are just reinventing the wing?

Geoffy-Just move your plant to Maui!

KayakDoc wrote:I watched as they discussed .. to reduce bow movement at high speed.

Hmm. It is probably a good idea in general to reduce or eliminate high speed bow movements

KayakDoc - love the comment on just moving plant to Maui! Cannot imagine what the shipping costs of our carbon prepreg coming into Maui would be. Of course then one could say move over to thermoplastic composites or urethane infused carbon, which we may do anyway. But in any case we save over $1,000/delivery when shipping to WA rather than shipping to Sidney.

At the WC level it is all about rider input and social (mental) dynamic of rig to rider to board to interface to fin to water. So we end up tuning to rider (Adam in this case) and being highly specialized. I think it's more fun to just watch them doing that "work" - while doing a design of experiments approach to tune away from someone's particular distribution of muscle fibers and mental feel and into more of a global optimum for all the "almost WC" level riders.

Windsurfer board designers did this by pure trial and error for years and years and finally got it about three/four years back, as they played with length, volume/distribution, rocker, bottom shape, rails, etc. Now all boards are really, really good and light-years ahead of past efforts (right JellyFish) and some are excellent. Fins are next in my opinion, but more complex than other components (again in my opinion.)

So back to Maui - will be there again May 21 - June 3. Wedding is in Sprecks May 26th. All welcome, no presents allowed. Hmmm - maybe some parts of the company will be moved there.

Geoffy - I appreciate your thoughtful reply...as always. Although I believe kiters are smart enough to learn from windsurfers trial and error I wonder of there will ever be an omniscient enough perspective to achieve median kite gear designs. It seems to me that kite surf design is a lot of copy cat watered down from pioneering exploration by the best riders pushing their own limits e.g. “good student kites” are heavy duty construction, cheaper cost, with limiting control input copies of higher performance kites. So...do we design cutting edge and construct backwards or do we target audience? Seems from your discussion that trial and error was effective in achieving WS median performance products although if we could target audience we might not have to wade through “trial and error for years and years” to get across the start line. I wonder if we will ever be imaginative enough to envision the outcome and then construct the product, getting it right the first time (not just functional or the best to date). I suspect that products shape habits and that the best riders shake off these habits and become our design harbingers accordingly. I believe this might run contrary to your design priorities, but from this psychologists perspective good and evil reside side by side in every thought and action. Kinda off fin design huh! Congrats on the nuptials. See you in May.
PS
Note that Paolo and Adam occupy disparate roles from the ones you have noted....Paolo pushes the designs to the limit and Adam cranks them back into usable form!
P

P - sorry we got so busy with my friends up in Kula and didn't get back to you on that drink in October. Shall be fun, soon!

We are on the same page but approach it differently - I did understand the roles of Paolo and Adam from your post, my point was that by going this route, they are now "tuned" to Adam's optimal feel from Paolo's "design limit". This is exactly what windsurfers did from 1983 until the mid-2000's (and yes, I know it is also related to fin and especially sail improvements. Evolutionary circle.)

A board I had made in 1985 and took over to Maui was a wave 87L, 8'-1", thruster with assym front fins (9 cm if I remember right), couple degree toe-in and a couple degrees cant as well. Designed from application backwards, but suffered in that it didn't have adjustability to be able to experiment with design attributes. Was perfect for the sails I took it there with and not so good on the new Simmer RAFs over there (thus I didn't buy the Simmer's.) Would have been great to be able to do an experimental set and gain performance benefits that way (and not artificially rule out an improved sail at the same time - collateral damage.)

So - I think you design for the two things that truly count, functionality and manufacturability (creating technology to overcome limits either poses) and early on perform a proper experimental set to understand how variables interact, then let loose from a "really good" design point and let imagination run wild from there. I would argue that's what single fin windsurf boards did - got to really good - and then twins, thrusters, quads took off from there.

I think my psychologists are trying to resolve problems that run much deeper than my design priorities, like why do I let a bad 25-year old looping injury still block me from attempting now! And more importantly, why does it matter to me? Hmmm - need some sun and wind to explore this in detail. The US approach, pharmaceuticals, would probably help too.

Congradulations on the nuptuals Geoffy