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SIEVE Surf Fins Guide

But which fins do I actually need and what models are there anyway? The sheer selection of surf fins can quickly overwhelm you. So that you do not lose the overview between different materials, designs, systems, driving characteristics, etc., we have written a small encyclopedia of surf fins.

One thing first: The choice of the right surf fins for you depends on three factors: your body size, your riding style and the fin box of your surfboard.

Surf Fins – a short history

Let's start at the beginning with a mini-insight into the evolution of surf fins: The emergence of the various set ups historically followed a logical sequence. The first surfboards did not have fins, today these boards without fins are called Alaia boards. In the period between 1920-1960 surfboards were then mostly surfed with a center fin, the so-called single fins. With shorter boards and new materials, boards with two fins began to be surfed (twin fins). In 1980 Simon Anderson developed three fins on the board, which is still the most common set up today.


The size of your fins also plays a role. Larger fins give you more support and control, with smaller fins you are more agile. You should also coordinate the size of your fins with your own body weight.

Set ups

Surfboards come with different fin boxes. The fin boxes and how you use them determine your set up. The most common set ups are:

Thruster - The Thruster set up is the classic set up. Not because it is the oldest set up, but because it is the most common fin set up. It is considered an all-rounder and provides stability, control & maneuverability. The Thruster Set up is suitable for most conditions.

Single Fin - The Single Fin set up comes with a single large center fin and is mostly used on long & oldschool boards. Due to the single large fin it has a lot of drive and is optimal for fast, straight-line surfing. Turns are softer with the single fin due to the limited turning behavior. If the fin is placed further back in the box, it provides more control, and if it is placed further forward, it provides a looser feel.

Twin Fin - With the Twin Fin, two larger side fins are attached. This set up is especially popular with retro fish. You gain a lot of drive, but lose some control compared to the thruster set up. With a twin set up you can make longer, more drawn out turns.

Driving characteristics

The set up, material and size of your fin influences the riding characteristics. These properties mainly affect the following variables:

Drive - Speed that can be built up, for example to bridge weaker sections.

Hold - grip that the board has in the wall

Pivot - turning radius that the board has. Determines how narrow or wide turns can be driven.


Basically, fins can be 'glassed-in', which means they are permanently attached to the board or they are removable. Most fins, however, are removable. Surfboards are equipped with a fin box into which the appropriate fins can be inserted and then tightened with small screws using a fin wrench. There are different systems for this.

FCS I & FCS II (Fin Control System) - is the world's leading system and was patented by FCS in 1995. A distinction is made between FCS I & II. FCS I fins have two plugs at the bottom, these are inserted into the box and then tightened with small screws using a finkey. The FCS II system was introduced in 2013, and works with a clip-in, so no tools are needed for installation. However, many manufacturers continue to use the FCS I system (as with our thruster sets).

Future - is the second largest system manufacturer. Here, the fin is inserted over the entire length of the finbox and also attached with a set screw.

US-System - is the most common system for the single fin set up. The fin is centered on the board. By positioning it further back or forward, the maneuverability can be influenced. Here, too, the fin is fixed in the desired position with the help of a screw.


The material of your fins determines how flexible they are. A fin with a firmer material allows for more direct power transfer and therefore more precise control. The more flexible your fins are, the spongier they can feel. A fin will feel firmer the higher the fiberglass content of the material.

Plastic / fiberglass blend - the most common material from which our fins are also produced. The plastic is light and flexible and gains the necessary strength from the fiberglass content. For most surfers, this material is perfectly adequate. However, the fins are more flexible than fins made of pure fiberglass or carbon.

Performance Glass / Fiber Glass - 100% glassed fin, making it heavier and stiffer. Fins that are 100% fiberglass are usually very sharp.

Performance Core Carbon - Glassed fin with foam core and carbon reinforcement, these fins are aimed more at professionals.


That was a lot of information. The best way to find out which fin is best for you is to try out different set ups. Of course you are welcome to contact us! And as always, it's worth thinking about, but you shouldn't make a rocket science out of choosing your surf fins.


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