Surfboard fins, where do we begin? Because, let’s be honest, surfboard fins can get a bit (or a hell of a lot), confusing. No matter if you go to your local store or if you visit an online store, the scenario is mostly the same: huge, bright multicolored amount of fins that come in different shapes, sizes and brands, all of them greeting you saying “pick me!.”

By the time you finish reading this post, you will be able to navigate the minefield that fins represent and find your nirvana: understanding what a fin is, how to choose the right one for you and a bit more. 

Should we start? Sit down, buckle up and keep reading.

| Deconstructing a Fin

Point number one, fins are too important of a matter for your surfing experience, so let’s start getting to know them a bit better, shall we? Point number two, choosing the best fit for you is not only a matter of the type of board you ride, but it is a matter of your weight, surfing abilities and everything in between as well.

Main Function | What is the main function of a fin? In two words: control & direction. The fins will really affect the way you surf a wave and that’s because their main function is to allow you to convert speed generated by falling (gravitational), into horizontal and upward speed enabling you to drive the board where you want to go on a wave. Meaning, fins will give you control and allow you to pivot and change direction. 

Picture a board with no fins: without them it would be difficult to stay ahead of the breaking part of the wave, right?

Talking about types of materials, we are going to cut the conversation short and make it ease for you: surfboard fins are usually either fiberglass, plastic or carbon fibre. 

The size that you make the fin and where you place it will dictate how much you can go up the face and down the line.

Steve Lis, Sunset Cliffs kneeboarder and shaper.

Now, how you move/surf on a wave and how the fins allow you to, is another story and it has to do with the type of fin set-up; the shape, size and construction; and let’s not forget, the type of waves you are about to surf and your ability to do so.

A Surfboard Minefield? Reach Your Nirvana

Tristan Mausse holding Fantastic Acid special fins in Anglet, France.

| Fin's Anatomy · The Basics

Fins play a central role on how a board will perform and their anatomy is key to what your surfing experience will be: size, shape, contour, foil’s thickness … How the surfboard feels, can completely change depending on the fins you choose to ride it with.

You may be thinking that there’s no need to know the elements of a fin in a techy way but, we are telling you, it is quite interesting and can come handy as well. So let’s get to know them a bit better to make the best and most efficient choice when getting them.

The gravity force pushing  you straight toward the beach gets greater as the wave gets steeper. That is why more fin is needed to resist movement in this direction, so the lift force created on the fin as the boards slides sideways stops the board from sliding too far. This is how a fin should behave, if it works properly.

|  Pro Tip | The greater the fin height /base length / rake / area = better holding power

• More Fin Area = Force exerted by water on fin holds the board in position
• Less Fin Area = Small force can’t hold the board in position; weight wins out, board side slips

Virtually every surfboard in the world has a fish shaped template fin. The high aspect ratio with narrow chord helps maintain laminar flow maximizing lift and tip flex to eliminate tip vortex.

Bob McTavish, Board Designer. 

|  Pro Tip | The greater fin height = greater resistance to rail to rail turning.

Height | A fin’s height is measured from the base to the tip. You’ll have more control and stability the larger the height of the fin, so this is a good fit for you if you are a beginner or a less experienced surfer. For increased manoeuvrability and ‘radical’ turns, a shorter fin would be advised. When you start checking fins, you will see that they come is different sizes: extra small [XS], small [S], Medium [M], large [L], extra large [XL]. We’ll get to that later but, with this information and your size, you have the basics for choosing a fin quite covered.

Base Length | The length of a fin is at its base. Longer base translates into more speed and predictability. Shorter base, allows for increased manoeuvrability instead, so you’ll be able to perform sharper and tighter turns.

|  Pro Tip | Greater fin base length and longer rake = more difficult lateral rotation.

Rake | Length of the front edge of the fin, meaning how far back the fin curves from the base to tip. Want speed and predictability? Go for a small rake fin. If you like short, fast tight turns, go for a larger rake instead.

|  Pro Tip | Streamlined foil = laminar flow = holding power

Turbulent flow will do a poor job resulting in loss of hold or side slip because of a variable pressure and drag.

|  Pro Tip | Asymmetrical side fin foil = lift toward wave face = directional holding power

Efficient Fin Foil | Usually you will find that fins have slightly different foils. A thruster has a symmetrical middle fin with the side fins being a bit rounded on the outside (asymmetrical fins). These asymmetrical fins, that we find as side fins in the thruster or twin fin boards, create a hold improving force. The longer curved surface on one side of the fin, creates a water pressure difference which results in an horizontal force acting toward the curved side of the fin, improving holding power against gravity.

Efficient Fin Foil | Usually you will find that fins have slightly different foils. A thruster has a symmetrical middle fin with the side fins being a bit rounded on the outside (asymmetrical fins). These asymmetrical fins, that we find as side fins in the thruster or twin fin boards, create a hold improving force. The longer curved surface on one side of the fin, creates a water pressure difference which results in an horizontal force acting toward the curved side of the fin, improving holding power against gravity.

 The Surfer Hugo Ortega flying with a Pukas Roach combo set up as a thruster.