Beginner's Fin Guide: How to Choose Size, Shape and Construction
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Beginner’s Fin Guide: How to Choose Size, Shape and Construction

March 14 2018 Categories: Tips and Tricks, Uncategorized

The shape and size of your fins can make all the difference when trying to progress to that next level. If you’re just getting in to surfing, your first priority is to be on a board that’s right for you. See our guide to Mini Mals, here: Why a Mini Mal surfboard is ideal for beginners…

But as you progress and find yourself sticking basic manoeuvres much more often, it might be time to dig further into the details of your setup. And that’s why we’re here.

Below we’ll aim to better your understanding of fins in general and explain how the right blades in the bottom of your board can enhance your surfing. So, when your next staring down a stacked fin wall which we know can be a little daunting, hopefully you’ll have a better idea of where to start.

The basics…

Surfboard fins serve two purposes: adding stability and grip so that the tail of your surfboard doesn’t slide around, and helping you generate speed off your turns.

As you’re up and riding, the water obviously moves from front to back passing through your fins. Then when you begin to turn your board by sinking the back of the rail, (edge of your board) your fins engage. By engaging your fins, you are pushing them against the water travelling down your board. The resistance caused from the surface area of the fins pushing against the water will give you your propulsion, known in surfing as drive.



Without over-complicating the science of hydrodynamics, these six areas are important in understanding how the shape of your fins will impact the feel of a surfboard:

  • Fin area
  • Base length
  • Fin Depth
  • Rake/ Sweep
  • Fin Cant
  • Foil

Fin Area

Larger fins will give you more hold and more control on bigger, faster waves as there’s a larger area gripping the water. The heavier and more powerful surfer will also be able to get more drive/speed from larger fins as they can convert extra weight into power helping push the fins through the water.

Smaller fins will be looser however, you will lose drive and control in bigger surf. Smaller fins are better suited to the lighter surfer where larger fins might make the board feel stiff and unresponsive.

Scarfini Fins Size Guide:

XS: Under 50kg
S: 45-65kg
M: 60-80kg
ML: 70-90kg
L: Over 80kg


Fin Base

This part of the fin which is connected to the bottom deck of your board is known as the base. A bigger/longer base will provide more drive whilst giving you a more drawn out, arcing turn. A shorter base will give you less drive however, this will give you the ability to pivot the board more easily in a smaller area.

Fin Depth

This measurement is taken from the base of the fin to the tip. The deeper the fin, the more hold you’ll have, whilst a shorter fin will be looser and allow the tail to release more easily.

Fin Rake/ Sweep

This is the angle that the fin is swept back. The more the fin is arched back, the longer your turning turning arc will be. This is great for surfing waves with big, long walls so you can draw out more powerful turns. The more upright the rake, the more you can pivot off your back foot making them great for snappy top to bottom turns.


The cant in a surfboard fin is the outward angle of the fin in relation to the deck of the board. If a fin has zero cant, its position is straight up and down at a right angle to your board. This means it’ll be fast in a straight line as there is less drag but it won’t provide as much responsiveness when trying to turn. The greater the cant, the more responsive your board will be through turns meaning you can maintain more drive.


This is the cross sectional shape of the fin which determines how the fin will perform as water passes across it. Usually you’ll find that a fin is thicker through the centre and tapers out towards the edges. Side fins on thrusters, twins and quads are often flat on the inside with a foil on the outside edge whereas centre fins are symmetrical.



Soft Fins

Most commonly found on soft boards and beginner boards, the main feature of these is safety making them a great first option, especially for kids. This fin will also have a lot of flex meaning they won’t generate too much speed and will be very forgiving.

Composite Surfboard Fins

These are the most common fins usually given away with new boards. They are made from either a combination of plastic and fibreglass or just pure plastic. These will be slightly faster in the water than their soft counterparts but will maintain flexibility and lack speed. Being slower, this composite option means you’ll have more time between manoeuvres and while they might feel a little spongy through turns, they are a good, forgiving first option on a hard board.

Fibreglass Surfboard Fins

These fins will have a fibreglass construction, with the majority of these fins being performance core. The fibreglass construction will make these fins stiffer and therefore faster and more responsive, whilst the performance core (usually honeycomb), adds strength but keeps the fins lightweight.

Carbon Based Surfboard Fins

These are the ultimate for performance. They combine the ultra stiff and lightweight characteristics of carbon fibre with lightweight fibreglass resulting in an extremely stiff base. This gives you maximum drive and acceleration as the fin is not flexing and losing energy. However, the combination with fibreglass is still necessary to allow a minimal amount of flex; a purely carbon fibre fin would be fast but feel quite lifeless through turns.

So, if you feel you know what you need to take that next step, check out our full range of fins, HERE

Or if you have any further questions, don’t hesitate to give one of our experts a call on 01548 854676.

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