Fins are attached to the underside of the board in the rear area. They give the board stability, control and allow you to take turns. Some surfboards have fins that are permanently laminated, but most have removable and replaceable fins.

The fins themselves come in different designs, shapes, sizes and are made of different materials. The type of fins used affects how a surfboard handles, as does where they are placed. Overall, it is a complex system that has to be adapted to the respective surfboard.

Fin systems: There are different fin systems. The FCS system has established itself worldwide and many shapers install so-called FCS plugs in their boards, which enable the use of FCS fins. There are also other fin manufacturers such as Future Fins, who advocate a different form of attachment. There are even board producers, such as BicSurf or NSP, who have developed their own systems.

There are now 3 generations of the FCS system: normal FCS1 plugs (two plugs per fin), FCS Fusion (1 box per fin), FCS2 (1 click box per fin). Fortunately, the fin systems are backwards compatible. An FCS1 fin still fits in all systems.

Task of the fins: First and foremost, the fins ensure that the board always moves in the direction of the nose. This is achieved by the different levels of resistance generated by the fins. On the one hand, the resistance in the rear board area ensures that the board remains stable in the direction when riding straight ahead, on the other hand, the surface of the fin also ensures that the board does not slide sideways down the wave. The second task of the Finns is to provide the "drive". By using the fins, the energy of the wave should be converted into a forward movement. Drive provides acceleration during and out of corners.

Fin Selection Criteria: Regardless of the manufacturer, here are a few general tips for fin selection:

• The heavier the surfer, the larger the surface of the fins can be
• Strong surfers choose fins with a larger surface area
• A small fin, one with less camber (more upright), or more flex will give a rigid board more maneuverability.
• To give a board more stability, fins with more surface area, more curvature or less flex are used
• To make a board more forgiving, choose fins with a lot of flex.
• To make the board more reactive, choose harder fins
• On boards with a large rocker, fins with a larger surface area and more flex are more suitable than boards with a small rocker
• Boards with a large proportion of edges, such as guns or long shortboards, do not need such large fins
• Boards with deep channels in the tail don't need fins that big either
• Boards with wide tails require larger fins than those with narrower tails
• Boards that are supposed to work in bigger and stronger waves need larger fins