What is important is to create a guide in order to know which Fins to use in function with different parameters.
There are really only a few general rules to follow and they are not 100% reliable. So, I am going to give you the basic outlines I use. BUT, all big outlines have their exceptions and it is by combining these lines together that you will manage to make the right settings.
The choice of a Quiver :
The first rule is to do the testing yourself. It’s sooo hard un unscrew one little nut and bolt that you never do….. what a shame!! Make the habit of storing your Boards without the Fins mounted. This way, you will be able to stock store them better, you won’t mess up your Fins, and you will be able to play with the settings during each session.
Buy Fins!! For the price of a Board, you can buy upwards of 15-30 Fins !! And you need to know that 50% of the performance of the Board you have, or will have in the future, is due to your Fins, so creating a Fin Quiver is a smart thing to do. I’m not saying to go out and buy 15 sets of Fins, but having a couple sets gives you the pleasure of choice is not some luxury. You will end up really appreciating the full potential of your Boards.
Have Fins in your Quiver that are not far from each other in size. We often don’t change our 215mm Fin because the other one we own is a 160mm. Which is a huge difference!! It makes the choice even harder so we just end up not changing. Never lose sight of the principle of this overlapping because it makes a big difference. The standard is simple : in your Quiver, each one should cover a little bit of the intended use of the other so there are no holes when in use. For example, if you have a 12’0 and a 7’7 life is hard. On the other hand, if you have a 9’3 to use between both of them everything is easier because each Board can do a little bit of what the other Board can do. And if you don’t have the money for 3 Boards, then it would be far more prudent to go little by little and to have gotten a 9’3 before the 7’7 when sizing down.
In the water :
Some main principles :
The Shape :
The more sweep towards the back, the more maneuverable.
The more curvature towards the back, the more maneuverable.
The thicker it is, the more agile it and efficient at low speeds.
The straighter the Fin, the more drive you get.
The thinner the Fin, the better she does at high speeds.
The more volume at the tip/head the more agile it is.
The squarer and shorter it is, the more agile it is.
The thinner the head/tip the faster and more controllable it is.
The Roles :
The Center Fin gives the ability to accentuate the turns, it creates drive (control and directional stability), it creates rocker from rail to rail. When used alone it creates the principle hold of the rails.
The Laterals create the relaunch (for they pull the Board towards the inside of the turn) they insure the hold of the rails when the turning radius is enormous and engaged.
The Configurations :
Single Fins offer less drag, lots of speed, and an easy passing from rail to rail, and rounder turns. It can on hinge itself brutally on occasion when it comes out of the water. And once it does then there is nothing but the rails to maintain the hold on the wave.
The Twin Fin delegates the role of the Single to Two Fins that are located closer to the rail. Like this the re-launch is much more efficient and better speed can be generated when pumping and you’ll have a stronger hold when carving hard. This delegation also allows to progressively manage the unhinging from the wave because it’s better managed with two Fins.
The Tri Fin/Thruster repartitions the job of the Single. The hold and the re-launch is delegated to the Laterals and the directional function is done by the Center. This repartitioning allows to better manage the hard angles, to push them further and to reduce the turning radius because the Board tolerates it better, and also to change direction quickly without risking unhinging uncontrollably because the Fins will hinge-unhinge differently from each other.
The Quad repartitions this job out even more the Tri Fin. There are two types : those that double the Laterals and suppress the Center, and those that double the Center while holding onto the Tri Fin Laterals. The objectives are very different from the previous explanations.
Based off that, everything is possible !!!
Remember that all Boards can adopt all Fin styles and configurations. Some just work better than others.
The technical elements of the Fins should also be taken into consideration.
The prettiest ones aren’t necessarily the best ones !
The materials choice is fundamental.
The material assembly is also fundamental.
The management of Flex in general, and most importantly the head flex, is a crucial element in performance.
The type of Box is also very important because there are Fins that to not like to be handled on the daily basis, others are too soft, and some too fragile…. Mu opinion is that they need to be solid and easy to use.
Complete Clarification :
Make note of the importance to understand the role of the major types of Fins :
Very Large = made for low speeds and lateral hold. Anti 360° and low speed supports and to avoid falling when in a turn.
Very Thin = fast and stable at high speeds. Attention, the slightest error and its total FUBAR. But they have low drag.
Lots of Rake = the larger degree of Rake, the more drawn out your turns will be. The more Rake the less pivot your Fins will have.
Very Straight-Lined = the profile is a bit more susceptible, but when it works it works. The angle of the Rake needs to be adapted to the rocker, then It’s magic. Note : If the angle tis to extreme, the Fin will affect the Board in such a way that if you rear/tilt it, it will make the Board more playful. It’s also a Fin that’s easy to 360° or when breaking turns because of it….. once the flux unhinges, there’s nothing behind it to bring it back (obviously schematic).
Very Vertical = nothing moves. You get the sensation of a huge Fin in proportion to the real surface. Fantastic for Noseriding.
Too much Sweep towards the back = the Fin will feel twice as short. It’s great. Less power but who cares….. perfect for 360°s and you can keep the Fin length.
Wide base thin Tip = very smooth rail to rail and progressive unhinging. Good max Speed.
Small base big Tip = rail to rail hard and violent. Sure moves and throwing down hard. Feeble at high speeds.
Thin Profile = great at high speeds and good when unhinged at low speeds, feels like nothing underfoot. Under 1cm in thickness, you’ll find yourself not equipped correctly in less than shoulder high waves.
Thick Profile = you’ll definitely feel like there’s a keel under you !!! Great at super low speeds because you’ve got something to mush on. The day we make inflatable rails on a Board is a day they’ll be interesting, these types of Fins are of no interest, but until we can augment rail volume to an XS = we add more volume to the Fin.
Profile with Thickness at the Tip = after having just written that, in this case we have a lot of lift at the tip and hold at low speed. The Board moves incredibly well in the turns and holds up to pressure. You know it’s working well….. when you’re going slow ;).
Profile with a Decreasing Thickness = the standard because it offers mellow behavior, progressive, typical. Yep.
More complicated, profile that’s curved at the front and straighter at the back = you can attack the turns but it brings you straight back in line. The boards nose is freed up but blocked at the tail.
Profile more curved at the back than at the tip = a good balance. It accelerates in the turns if we push on it. Very versatile.
Maximum thickness at leading edge, around 80% = great at low speed, drag and whistling at higher speeds. Turning is fast at the leading edge and the rest is flux.
Maximum thickness of the back of the profile, at 50% = that’s full on. Well not so fun on a SUP because they are slower. Don’t get crazy. That’s the reason why a Windsurf Fin is lame on a SUP. The flux doesn’t hold well at the front or what to trust at the back. It’s not good under 20 kts (SUP surfing is usually under 6-17 kts in general).
Maximum thickness that goes from the base to the Fin tip. Very clever but not often used, or never. Flux doesn’t go back and forth on a profile. There is a strong vertical component that gets worse as the profile is tilted backwards (which is why tilted profiles are thinner, because water gets blocked there longer). In short, adapting the positioning of the maximum thickness as you approach the tip to adapt to the acceleration at the tip is an idea that holds promise in the future.
The vortex of the tip = the flux flows with a vertical profile then suddenly…….nothing to hold onto. Analysis : they swirl on onto each other (like a tornado in reverse). You’ll say that it’s no big deal, but YES. This drag creates a depression/turbulance that sucks the profile towards the back. If you exaggerate this, the Fin tip will end up in cavitation and bazinga…… in 360°….. bad luck. To limit this, don’t drag your Fin in the sand and keep it honed and sharp, no jagged edges.
The twist = a Fin that has too much flex will generate a foil effect : it will lift the Board up. Too much for good turning, lame for accelerating because the energy is lost in vertical, it all gets pushed upwards so it’s no good.
The flex = The Fin can fold laterally. But its connection within the box can double the problem. Keep it tightened down !! Everything that moves is your enemy !! If not, everything I’m explaining to you means nothing.
The Tri-Fin = The hold on the wave is put on the laterals while the pivot (the winding of your hips) is on the center Fin. It’s your job to find the balance.
The angle of the Lateral Fins (Fin Toe) = the more inclined they are towards each other the more maneuverable the Board, but the slower she’ll be. And inversely the further they are angle towards the rail, the faster you’ll go.
The position of the Laterals (Fin Cant) = This is the degree of outward angle the Fin has in relation to the bottom of your Board. Zero Cant, means it is straight up and down at a right angle with your Board. Fast in a straight line, but unresponsive in the turns. More Cant means a gain responsiveness in turns and more drive when tilted on the rail.
Position of the Center Fin = The more advanced the more maneuverable. Evidently, if you put it all the way back the Board is even more agile, but that’s because you’ll be cheating when you’re stalling. The further back it is the better she’ll hold up going straight down the line fast, stable but less maneuverable. With the same thought, the thicker the Fins Tip, the faster she’ll put you back in a straight line.
The Quad = either we double the Center Fin to spread out the pivot under your huge foot sized 47 (weaker legged fools will have a hard time). Or, we double the Laterals and focus on the projection through the turns. It’s fast but flawed.
The Tango = Famous Puerto Rican Dance from the 20’s that was bump and grind with four fat bearded dudes.
You understand, I’ve already cut down this down, I could have written 200 pages more on the subject…… anyway, you got the bases. Don’t forget that the manufactures neglect Fins 99% of the time because they’ll lose their marge. It can get expensive and each of us needs to find our own perfect set-up.
Whew…… that was a mouthful….;)!
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Source : Team GONG, how to choose your Fins.
