A Quick Guide to Surfboard Fins
Are you curious about what those daggers on the bottom of your board do? Surfboard fins are an essential part of performance and wave riding ability. Here is a quick guide so you can pick the best fins for your board.
What Does a Fin Do?
Fins are responsible for direction, control, stability, and come in a large variety of sizes, shapes, setups, and materials.
Types of Fin Set Ups
Single fin
A single fin is the most traditional setup and most often found on longboards or longer short and fun boards. They offer better control, less drag, and are ideal for basic, fast, straight lines.
Twin Fin
The twin fin is most commonly found on shortboards and offers more maneuverability, responsiveness, and allows for longer and more drawn-out turns.
Thruster
The thruster fin setup is the most common configuration and works for any size board. The additional fin adds stability, and the two outer fins are toed in towards the center for better tracking and speed on waves.
Quad Fin
The quad fin adds even more stability and speed to your board. The extra two fins direct water toward the end of the board and out the tail for better acceleration. They are perfect for making big, fast, turns.
5 Fin
You won’t see boards with 5 fins very often. Most boards have 5 fin boxes (the spot where the fin is inserted into the board) to give the rider freedom for how they want to configure their board that day.
The Components of Fin Shape
Fin shape determines how a board will perform. Many different components make up the shape of a fin, and little tweaks can make a load of difference in turns, control, stability, and more.
Fin Size
Fin size impacts performance. A larger fin will have better hold and provide better control in bigger waves.
Fin Base
The fin base is where the fin is attached to the board. Longer fin bases give more drive and are great for big, long, swooping turns. Shorter or narrower fin bases allow for quicker, sharper turns.
Fin Height
The fin height or the fin depth is how far the fin extends from the bottom of the board. A longer or deeper fin provides more hold and stability. A shorter fin has less hold but allows for easier turning.
Fin Rake
Fin rake or fin sweep is how far the fin tilts back on its arc. The larger the rake or sweep, the longer your turns will be. Smaller rake means quick turns and better handling in small, mushy surf.
Fin Foil
The fin foil is the aerodynamic shape from the front to the back of the fin. Foil generates lift in the same way as airplane wings, and different shapes help differ in the performance of the board.
There is a lot of diversity among fin foils. Side fins on thrusters, quads, and twin fins are usually flat on the inside and sometimes curved inwards. Center fins are typically flat or symmetrical on both sides, also known as equal foil.
Fin Cant
Fin cant refers to the angle outward of the fin from the bottom of the board. No or zero cant means the fin is positioned straight up and down at a 90-degree angle and will be fast, but lack responsiveness. The larger the cant, the more responsiveness and drive in your turns.
Fin Toe
The fin toe is the angle at which the fin is pointing towards the stringer (the centerline down your board). Different levels of toe determine different levels of performance, and the greater the angle against the stringer the more responsive the board.
Fin Flex
The fin flex is the amount of movement of a fin from side to side. A stiff flex means less movement and usually translates to quicker turns but less drive. A more flexible fin will have longer turns with more drive.
Want to Learn More?
Here is a guide to the physics of surfboard fins and their function.
Now that you know the basics about surfboard fins, it's time to put that new understanding into action. Check out the Jamie O’Brien Surf App here for more insight on how your fins impact your surfing.
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