Everything You Wanted to Know About Surfboard Fins But Were Afraid to Ask
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All You Need to Know About Surfboard Fins to Tweak Your Ride
Surfboard Fin Basics
Choosing the Right Fins
Surfboard Fin Basics
Surfboard fins are found underneath every surfboard, usually toward the bottom back end. Surf fins are an essential part of a surfboard and play a number of important roles.
Fins are the keel of a surfboard (the positioning of your body weight, using your feet, is like your steering wheel). Without fins you would have no control of the dir
Surfboard fins are found underneath every surfboard, usually toward the bottom back end. Surf fins are an essential part of a surfboard and play a number of important roles.
Fins are the keel of a surfboard (the positioning of your body weight, using your feet, is like your steering wheel). Without fins you would have no control of the direction of the surfboard. Fins allow you to turn left and right and keep you from falling off the face of the wave. Some call this the ability to hold on to or grab a wave.
Friction is created between the fins and the surf when a surfer pushes down with his/her foot on the back of a surfboard. Pressure from the feet and changes in body placement will cause the board to turn right or left.
The importance of fins in tweaking your ride is lost on many surfers. A fins shape, size, weight, material and placement changes the way the surfboard responds on the wave. Changing out fins can give you a refreshed, more enjoyable ride and make your old board feel different and new again.
Basically, the two extremes are: 1) A board feels looser and control is lost and the board may slide during turns with smaller fins (less sweep, area and length; see Fins Terminology), 2) The control will be greater, with more drive (control through turns), and the ride stiffer with larger more engineered fins (less flex, more sweep), which can help beginners.
Surfboard Fins 101
Choosing the Right Fins
Surfboard Fin Basics
A surfboard fin is a hydrofoil (think fluid mechanics, if you can) which is attached perpendicular to the board at the bottom of the tail.
The lateral lift the hydrofoil fin creates provides directional stability and control through steering with foot pressure. The lateral lift is opposed to oncoming water as a surfer rides a breaking wav
A surfboard fin is a hydrofoil (think fluid mechanics, if you can) which is attached perpendicular to the board at the bottom of the tail.
The lateral lift the hydrofoil fin creates provides directional stability and control through steering with foot pressure. The lateral lift is opposed to oncoming water as a surfer rides a breaking wave. It also stabilizes the surfboard's movement forward or trajectory. The fins and the bottom of the surfboard provide the rider control surfaces.
Surfboard fins were a huge advancement over the maneuverability, control and performance of early surfboards. Their engineering, design and material improvement has reached a renaissance in recent years.
Surfboard fins are outfitted on boards in various quantities and configurations. They are now available in many sizes, shapes, and materials (see Fin Materials), all designed to customize your ride. The earliest fins were created and used in Hawaii, where the original surfboards were also invented. Fins are used on all surfboards.
Choosing the Right Fins
Choosing the Right Fins
Choosing the Right Fins
- If your board feels too stiff (not enough speed) use smaller surfboard fins or fins with less sweep or more flex (see Fin Terminology).
- If your board feels too loose and slides through turns, use bigger fins, a stiffer flex fin or a fin with more sweep for more drive (control).
- A lighter rider requires less fin area to provide enough hold
- If your board feels too stiff (not enough speed) use smaller surfboard fins or fins with less sweep or more flex (see Fin Terminology).
- If your board feels too loose and slides through turns, use bigger fins, a stiffer flex fin or a fin with more sweep for more drive (control).
- A lighter rider requires less fin area to provide enough hold on a wave.
- To make a board more responsive, choose a fin constructed of stiffer materials.
- Boards with long rails and close fin clusters (known as guns) require less fin area (even guns used for giant surf use small to medium fins).
- Boards with more bottom curve (rocker) should use fins with more area, depth or sweep.
- Boards with deep tail channels need less fin area (small tips can increase the release out of turns).
- Boards with wide tails need more fin area than those with narrow tails (fishes).
- Small boards in big or powerful waves need larger or more swept fins.
- Different sized fins give the surfboard different capabilities. Switch out fins to experiment with your board and its performance.
Fins Hardware and Tools
Fins Hardware and Tools
Choosing the Right Fins
Futures, FCS, Single Fins
The most common surfboard fin systems (Futures, FCS, Bahne/US) use metal grub screws or screw/nut combinations to stay on your board.
Hardware gets worn or lost the more you use your board. Replacements are not hard to find. Surf shops will have grub screws, slotted screws, and nut plates on sale or extras for free
Futures, FCS, Single Fins
The most common surfboard fin systems (Futures, FCS, Bahne/US) use metal grub screws or screw/nut combinations to stay on your board.
Hardware gets worn or lost the more you use your board. Replacements are not hard to find. Surf shops will have grub screws, slotted screws, and nut plates on sale or extras for free. Avoid hardware stores.
The more often you rinse your board and hardware after a session the less likely your fins will get stuck. Key driver tools should be replaced if they get loose or worn to avoid stripping the head.
Single fins stay tight using a pin through a slot in the fin box and are secured using a screw and square plate. A small amount of epoxy can be used to keep the pin in place.
Futures fins feature a single hex head grub screw that fastens the fin into the box with an allen or hex key.
The original FCS system uses two grub screws, one for each tab and an allen or hex key to secure them.
Fin Materials
Fins Hardware and Tools
Fin Terminology
Molded Fins
Molded surfboard fins are manufactured using a composite mix of materials. Most of these fins have more flex. At this time, molded fins are the most common. FCS refers to them as Glass Flex or Composite. Future calls them Natural Composite or Composite.
Similar to old glass-on fins, layered fiberglass fins have
Molded Fins
Molded surfboard fins are manufactured using a composite mix of materials. Most of these fins have more flex. At this time, molded fins are the most common. FCS refers to them as Glass Flex or Composite. Future calls them Natural Composite or Composite.
Similar to old glass-on fins, layered fiberglass fins have a solid flex. The base is stiff with more flex at the tip. These are most popular for surfers who want to re-live the throw-back performance of glass-on fins. They also enjoy the ability to remove these new fines and swap out other designs. Futures refers to their fiberglass fins as simply fiberglass. FCS likes the more sophisticated Performance Glass (PG).
The most high tech fins use RTM construction which utilizes high technology that began in the aerospace community for flight. Glass is sandwiched with layers of honeycomb foam which creates a super-strong, very light, waterproof material. RTM fins are the best-sellers due to their high performance, strength, light weight and high tech appearance. There FCS refers to Performance Core (PC). Futures labels them RTM or HEX.
Fin Terminology
Fins Hardware and Tools
Fin Terminology
Base
The base refers to the length of the area where the surfboard fin meets and is secured to the surfboard. The base is important to the drive, lift and acceleration of the surfboard.
Depth
Depth describes how far the fins plunge into the ocean water. Obviously, shorter fins do not grip the water as effectively as larger fins and may resul
Base
The base refers to the length of the area where the surfboard fin meets and is secured to the surfboard. The base is important to the drive, lift and acceleration of the surfboard.
Depth
Depth describes how far the fins plunge into the ocean water. Obviously, shorter fins do not grip the water as effectively as larger fins and may result in slippage in some surf. Long fins can feel slower but produce better drive. As a rule of thumb, fins of 5 inches or greater are considered large. Small fins measure at approximately 4 inches or less.
Area
Base and Depth can be used to calculate the area of the fin. You should determine, usually through trial and error, the correct fin size (area) large enough to hold the board on the wave without sliding off but small enough to allow for effective drive in controlled turns.
Sweep
The sweep of the surfboard fin describes how far a surfboard fin angles backwards. The further backward the sweep, your turns will be wider or more rounded. A straighter fin enables tighter turns (FCS nomenclature examples are: upright fin = TC Redline; a highly swept back fin = YU).
Cant
The angle for how far your fin leans to one side.
Toe
The toe indicates the angle of the fin. If it is parallel to the board's centerline there is a 0 degree toe angle to the surfboard. The shaper of your surfboard has permanently set this angle.
Foil
Fins, much like airplane wings, are curved which creates a foil effect. Most often the middle or back fins are foiled on both sides. Side fins are commonly flat on the inside and foiled on the outside. Recently a handful of fin designers have used a slight foil on the outside fins (FCS has begun offering fins with inside foil). Hydrodynamically a fin foil causes areas of high and low pressure to move through the wave to keep you in by moving from high pressure to low pressure. This is similar to how a plane stays in the air.
Flex
Stiffer fins drive harder. Softer fins can offer less performance.
Drive Versus Speed
Drive relates to acceleration and maintenance of speed though turns.
Speed is how fast you go without which effects the relative ability to turn or stay on a wave.
Stiff Versus Loose
Basically, an overly loose ride happens when your fins are larger than you need. Too stiff a ride occurs when fins are too small. Too loose will slow you down. Too stiff will cause slippage but allow for higher speeds.
Types of Fins
History of Fins
History of Fins
There are three main types of surf fins:
Soft (aka flexible) fins are used on many rental boards to avoid injury liability. They are, of course, safer than a hard fin but there is a sacrifice in performance.
Permanently adhered classic glass on fins are attached to the surfboard by laid on fiberglass. Thi
There are three main types of surf fins:
Soft (aka flexible) fins are used on many rental boards to avoid injury liability. They are, of course, safer than a hard fin but there is a sacrifice in performance.
Permanently adhered classic glass on fins are attached to the surfboard by laid on fiberglass. This was the method of choice for old school surfboards before the advent of the fin box. That technology advance made glass on fins mostly obsolete because they are damaged easily and require now rare expertise to repair.
Fin Systems that use a fin box are the most popular option today. Removable surfboard fins are can be unscrewed from the surfboard and replaced by various fin designs or even be relocated on the board to vary setups to customize, experiment and tweak your board's maneuverability, stability and speed.
History of Fins
History of Fins
History of Fins
The original wood surfboards were used in Hawaii and, without fins, curved hulls and the surfer's dragged foot provided the only steering control. Of course the early surfboards were prone to slide in turns and slip off wave faces, causing riders to be thrown off their board.
The first surfboard fins were permanently affixed to the surfboa
The original wood surfboards were used in Hawaii and, without fins, curved hulls and the surfer's dragged foot provided the only steering control. Of course the early surfboards were prone to slide in turns and slip off wave faces, causing riders to be thrown off their board.
The first surfboard fins were permanently affixed to the surfboard by surfing founding father Tom Blake in 1935 in Waikiki. Blake pirated a metal keel from a neglected speedboat and attached it to his surfboard. The invention, even though primitive, opened a new world for surfers and kicked off a surfing revolution.
Later that decade, Woody Brown experimented with fin designs in San Diego, using stability and control fins, further advancing the popularity of the sport. Ironically, there remained a segment of surfers who were convinced surf fins were unsafe. By the 1950s though, fins had become a common fixture on all surfboards.
The 1960s brought more technical fin designs and multiple fin configurations on boards which led to the overwhelming popularity of short-boards.
Even though placing multiple fins on boards was first experimented with in the 1940s by Bob Simmons, not until the 1970s did multi-fin systems become much more widely-used, in competition and by average surfers.
Top pros at the time, including Larry Bertlemann and Mark Richards won using short-boards with twin-fin setups. The fin placement allowed for tighter turns in smaller surf.
In 1980, Australian pro surfer Simon Anderson unleashed the three-fin (Thruster) design (three fins with two near the rail about a foot from the tail, one center fin a few inches up from the tail) on the world, which remains a common standard today.
Most saw it as an advance from twin-fin configurations with greater stability, control and lifting for speed. Not only was it a breakthrough, after Anderson began to win competitions, surfers quickly adopted the Thruster design. It remains the most popular fin configuration for modern surfers for both enjoyment and competition.
Stuck Fins
History of Fins
Stuck Fins
To free up a stuck fin, pour some sub-boiling hot water over the base of the fin box to loosen up the accumulated gunk, sand and salt that has built up in there.
Then, take part of a towel, wrap it around the fin, wiggle it to loosen it, and finally pull back and down as hard as you can to pull it out.
If necessary, you can also try firml
To free up a stuck fin, pour some sub-boiling hot water over the base of the fin box to loosen up the accumulated gunk, sand and salt that has built up in there.
Then, take part of a towel, wrap it around the fin, wiggle it to loosen it, and finally pull back and down as hard as you can to pull it out.
If necessary, you can also try firmly swinging a rubber mallet in the same direction you need to pull to help it along. Only use the rubber mallet if you aren't worried about damaging the fin and are unable to pull it out with your hands.
If that doesn’t work, then try a spray of WD-40 directly at all four sides of the fin box.
If that doesn't work, either find a surf shop that will help you out with their fin puller or buy your own.
A puller was the only way we could get a stuck fin out of our 1970s Rick board, even though it had not been in the water much.
If you need to purchase a puller, we've had good luck with a brand called Finpuller (finpuller.com), which we find works well except on the really small fins.
We Recommend - Ho Stevie! Reinforced Polymer Surfboard Fins
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