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HomeHelpGuide To Surfboard Fins

Guide To Surfboard Fins


Fins have a huge impact on the feel, stability, drive and maneuverability of a surfboard – factors that can completely alter the way you experience surfing. This article provides some basic information on fins, from key terms and measurements to common setups, which will help you make educated fin-buying decisions.

Terms and Measurements


These terms describe elements of fin design that affect the way a surfboard will perform in the water.

TOE

The angle of the fin (box) in relation to the center stringer is known as a fin's toe. Most side fins can be described as toe-in, meaning that the front of the fin is turned in closer to the stringer. Toe-in causes the water to pressure the outside of the fins, which in turn makes the board more responsive to rider input.
CANT

The cant of a fin is the angle it makes in relation to the bottom of the surfboard. A fin that sticks straight up, perfectly perpendicular to the board's base contour, is said to have a no cant. Canted fins point outwards, toward the rails of the board. Increasing the fins' cant leads to a more responsive board through turns, while decreasing the cant (bringing it closer to 90°) makes the board faster, especially when traveling in a straight line.

FOIL

When you look at a surf fin, you'll notice that it is shaped in an aerodynamic fashion from its front edge to the backside. Most often, the thickest portion of the fin is the in the middle, while the thinnest part is the outer edges. This shape is known as the fin's foil, and it has a big impact on the way the water flows under the board. Some fins are flat on one side and foiled on the other (usually side fins), while others are foiled on either side (single/center fins). The idea is to create lift under the surfboard and help propel it most effectively in different wave conditions. The more pronounced the foil, the more lift it will provide. Unfortunately, this also causes more drag on the board, which slows it down.

RAKE

The rake measures how far back the fin curves in relation to its base. To find a fin's rake, imagine a flat line continuing out from the base of the fin; next imagine a line that extends from the back of the fin base to the very tip of the fin. The angle that these two lines form where they intersect at the back of the fin base is the rake. The smaller the angle, the farther back the fin tip reaches (a larger offset from the base). Fins with a small rake/large offset will propel the board faster and remain fairly stable, but there is a sacrifice in turnability. Fins with a large rake/small offset give the surfboard a tighter turning radius, but don't offer as much stability. As usual, you'll need to strike an effective balance determined by the type of waves you ride and the style of board you have.

FLEX

The flex or stiffness of a fin plays a big part in the way a surfboard will ultimately handle on the water. If you are a beginner, stiff fins are more forgiving and will give you the stability you need, so you might start there. Their lack of flex makes it hard to make sharp turns, and the turns you do make will be wide and sweeping. However, a stiff fin has the tendency to revert quickly to its natural position, so the turns will be faster than with a flexy fin.Flexible fins add a level of feel to the board that is hard to match with their stiffer counterparts. They are slower to reach their maximum flex, meaning the board continues to respond to the rider's input throughout a turn. This can cause some problems for new surfers, as it makes the board more difficult to control.

BASE LENGTH

This measures what is usually the widest point of the fin's outline – the base. The base length impacts the way that a board will turn and drive (accelerate through turns). A longer base provides more surface area to push against the water, so turns are stronger and drive is increased. However, the larger base doesn't permit the board to turn sharply, so if that's what you're after, go for a fin with a shorter base length.

HEIGHT / DEPTH

The depth of a fin is basically how far it sticks into the water, measured from the bottom of the surfboard to the tallest point on the fin. Depth affects the way a board will grip the water through turns, and it determines how well the board remains stable. The taller the fin, the more hold it will have in the water, providing the rider more control. While shorter fins don't grip the water as well, they do allow the board to slide-out a little, which some surfers enjoy.

Setups / Placement


Ever wonder why some surfboards have five fins, while others get away with just one? Simply put, there are countless setup possibilities, but only two major factors that greatly impact fin schemes: combined surface area and placement on the board.

The surface area of the fins – remember, we're talking about all of the fins added up – affects the way that the board feels and how easy it is to control. Greater fin area provides more control and stability, but also drags the board down. Less fin area gives the board more speed, but makes it more difficult to control.

Fin placement makes a difference in the way the board will respond and turn. It's easier to make tight, sharp turns with the fins placed closer to the center of the board (lengthwise), because the axis of the movement is more balanced. However, while it may be easier to turn, it is harder to control forward-set fins. If you need more balance and drive, you should try a board with fins placed closer to the tail. You'll feel more stable on the board, but turns will be wider and the board will feel stiffer.

Here are some explanations and suggestions for a few different types of fin setups:

ONE FIN (a.k.a. Single Fin)

Single fins are typical on longboards, as well as on beginning surfboards. The idea behind the single fin is to provide stability and control. Unfortunately, the increased control also means a sacrifice in performance, as the movements that a single fin allows are restricted to sweeping turns and straight-lined charges.

TWO FINS (a.k.a. Twin-Fin)

Twin-fin boards are harder to control in large waves but offer good maneuverability in smaller conditions. They are usually found on shortboards and fish boards, because the two-fin setup encourages speed.

THREE FINS (a.k.a. Thruster)

The thruster setup is the most common, and is found on all kinds of boards. It performs well under most ocean conditions, lending a stable feel to a maneuverable board. The outside fins are flat on the inside to increase drive, while the center fin is foiled normally. Additionally, the outer fins are toed-in to speed up the board and allow it to turn more easily. A thruster set-up is the go-to choice for most shapers.

Glasses-In vs. Removable


Surfboard shapers decide on the maximum number, placement and brand/type of fins for their boards before you ever see it in the store. However, the choice is still yours when it comes to your fins. Think of them as an extension of the board itself – if you don't like the way the shaper has the fins set up, the board probably isn't for you. That having been said, the first fin-related thing you'll want to look at when checking out a potential board is the system itself. Are the fins permanently glassed-in, or are there fin boxes that allow you to swap out the fins (if they break, for instance)? Here are some pros and cons of these two types of fin systems:

GLASSED-IN

This type of system is most common in retro, twin-fin boards, but some new boards do still come with glassed-in fins. Aesthetically, having the fins laminated right into the board appears pretty classy, but are there other benefits besides looks alone? If done correctly, glassed-in fins are structurally more sound than removable fins, because the entire base of the fin becomes a part of the board. The laminated fin base also affects the way that the board cuts through the water, so more experienced surfers will notice better performance as well. Now it's time to get real about the changing face of surfing. Glassed-in fins have become virtually extinct in the shadow of removable fin systems. They are a pain to replace if they break (not to mention expensive, as you'll need to pay someone to do it for you), they cannot be adjusted in any way, and they make traveling with your surfboard incredibly frustrating. Most shapers have turned their backs on glassed-in fins, instead opting to outfit their boards with newer fin technology. It's made a big difference. Read on…

REMOVABLE

Since the 1960s, shapers have toyed with the idea of removable fin systems. The problems posed by traditional glassed-in fins – they're hard to fix, ship and stock – finally led to revolutionary advances in fin technology on a mainstream scale. The 1990s saw a widespread shift from laminated fins to removable setups, and the surfing industry hasn't looked back since. Here's how it works: instead of permanently attaching the fin itself to the board, a fin box is glassed-in instead. Each fin box has a groove that only matches one particular brand of fin, but surfers can change the style, shape and size at their discretion. With very little effort and a fin "key" (a small screwdriver-like device for securing a fin in its box), it's possible to completely alter the type and/or number of fins on a board to suit varying surf conditions. Altering fin setups is quick and easy, usually taking less than a minute to complete.

While it's great that adjustments, travel, storage and repair have become easier with the introduction of removable fins, there are still drawbacks to the new equipment. The largest issue is, perhaps, coping with the sheer number of possibilities that this system offers. For newbie surfers especially, having to face the endless options associated with a removable fin setup can be daunting and confusing. Luckily, almost every surfboard comes with a set of fins already chosen for you. The shaper is charged with selecting fins that will best achieve the purpose of each board, taking the type of waves and style of riding into consideration.

Removable fin systems are easy, customizable, portable and inexpensive – but they aren't for everyone. Despite their benefits, some shapers and pro surfers refuse to go down that road, claiming that the simplicity and strength of glassed-in fins makes the surfing better. It's a choice you'll need to make for yourself, but at least now you know the whole story.

Fin Systems


Here is a glimpse at a few of the major movers and shakers in the fin industry, and the technologies they've introduced that make them unique.

FIN CONTROL SYSTEMS (FCS)

Fin Control Systems (better known as FCS) is a leading producer of quality surfboard fins worldwide; in fact, four of the last five surfing world champions were riding FCS fins at the time of their win. They are well made and known for their durability and performance. The key to FCS's success may be its revolutionary fin-plug design, whereby the fin box is anchored deep into the surfboard, grasping the laminates on both the deck and underside of the board. Most fin plugs are rooted into the foam core alone, then glassed into place using resin. FCS fin plugs are more a part of the surfboard construction, making them far more resilient and less likely to break.The interface between FCS fins and their fin plugs is also unique. Each fin is attached to the board by placing two prongs that stick out of the bottom of the fin into two separate, circular fin plugs. The fins, once screwed into place, are less likely to move laterally (which is a typical complaint regarding fin boxes). The result is a stronger hold back to front and top to bottom. Because their system is completely different from all other fin companies, FCS fins can only be used with FCS fin plugs.

FUTURE SYSTEMS

Future fins are another high-quality option for surfers. Unlike FCS's two-pronged fin plug system, the bases of Future fins are tapered to fit into elongated fin boxes, which are glassed into the board's bottom. The entire base of the fin is secured in the Future system with an angled screw, meaning that there is a strong hold from back to front. There is still a little wiggle room from side to side, so they need to be secured with a fin key every time you surf for maximum hold. Like FCS fins, Future fins are designed to only work with Future fin boxes. (Future does, however, make replacement fins that are compatible with other companies' systems, but they are marked as such.)

RAINBOW FIN CO.

The Rainbow fin system is similar to that of Future Systems', just with slightly smaller fin boxes. The fins themselves are the same size, however only a small portion of the base of the fin actually fits into the box, an interface that is unique to Rainbow. Like Future Systems, Rainbow Fin Co. know that not all boards come with their fin boxes; therefore, they allow customers to decide what type of fin base they need. Surfers can get Rainbow fins that are shaped to fit into systems other than Rainbow's own, such as FCS, Future, LokBox and others.

LONGBOARD FINS / FIN BOXES

Longboard fins are inherently different from normal shortboard systems. Unlike the typical fin that fits tightly into a fin box or fin plug, the base of a longboard fin fills in only part of its fin box. The idea is to lend adjustability to the fin setup; an extra long fin box means that the fin can sit closer to the back of the board (for more control), or closer to the center of the board (for looser turns and added feel). The fin slips into the box and is screwed into the channel that runs along the bottom (like Burton's binding system on snowboards). The ability to customize the fin to match the conditions of the surf is extra important for longboarders – especially those who don't have a huge quiver of boards to choose from.

PATAGONIA FIN BOXES

At the helm of Patagonia surfboard design team is Fletcher Chouinard, their in-house master shaper. The proprietary fin system that has emerged under Chouinard is unlike any other. Whereas most fins are screwed into place at the fin box itself (on the underside of the surfboard), Patagonia's fins are tightened from the board's deck. Additionally, the outline of the fin box, which extends through the entire thickness of the board, is made up of small curves, which serve to hold the fin in place extra snuggly.

TURBO TUNNEL

The Turbo Tunnel fin is like nothing else in the water. The innovative design features a tube running through the center of the fin lengthwise, which gives the fin the ability to grip the wave extra tightly. It is designed to give the rider longer nose rides, smoother re-entries, quicker turns, increased stability, greater overall control and more creativity in his maneuvers. The Turbo Tunnel fin gives a board more speed and maneuverability than a standard fin, and gives the surfer control over not only the forward direction and horizontal plane, but the vertical plane as well. It is designed for use as a single center fin or as the center fin in a Thruster setup.
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