SINGLE: A single fin is typically seen on longboards and provides speed, hold stability for nose riding.
TWIN: The twin fin is a two-fin setup. It increases speed and manoeuvrability. This setup will feel a bit loose, because there is no centre fin.
THRUSTER: The thruster setup incorporates 3 fins (of equal size). Like the twin fin setup, it provides stability and drive but also give the rider more hold because of the centre fin. This setup is usually preferred in high performance boards, but also the ideal setup for beginner boards.
QUAD: The quad setup utilises 4 fins. Compared to the twin fin, it may provide even more speed and hold in the wave.
2+1: A 2+1 setup incorporates 3 fins - 1 large centre fin with two smaller side fins. The centre fin will provide maximum stability whilst the two smaller side fins will provide extra control and manoeuvrability. This configuration is typically found on mid length boards.
5-FIN: This set up allows you to mix and match fins depending on your preference and the surf conditions.
As a rule of thumb, adjusting your middle fin should be done slightly until you get your desired performance outcome (i.e less slip, more hold). There is really no exact measurements to apply but good practice would be to move the centre fin approximately ¼ of an inch either back (towards the tail) or forward (towards the nose) until you get the feeling you are looking for.
A good starting point would be to place the centre fin all the way back (towards the tail), test the performance, then move it forward until you are happy. Generally if you feel the board slips too much on turns, then start moving the fin back towards the tail again. If its fit is too tight and you would like it to feel looser, then move it forward a touch.
All fins are classified by base, depth, area, sweep and foil. In order to chose the best fin for you, it’s important to understand how these characteristics can change the performance of your surfboard.
DEPTH: This is the distance the fin penetrates into the water. Depth directly relates to hold. The greater the depth, the more a board will slide and release.
BASE: This is primarily linked to drive. Fins with a longer base will offer substantially more drive and acceleration.
SWEEP: This is the angle measuring how far the outline of the fin is curved backwards; also referred to as rake. Sweep has a direct influence on pivot. Fins with more sweep produce a longer turning arc while less sweep offers a tighter turning arc.
FLEX: Flex refers to the bend of the fin caused by lateral pressure during a manoeuvre. Fins with less flex have more response, speed and drive. Fins with more flex are more forgiving and offer a whipping sensation.
CANT: This refers to the angle of the side fins measured from a vertical line perpendicular to the flat bottom surface of the board. Less cant produces faster acceleration and a stiffer feel. More cant will increase manoeuvrability and gives the board a loose feel.
FOIL: This refers to the shape and geometry of the inside and outside faces of the fin. Different foils create variations in water flow and affects overall performance of the fin and the board.