Kiteboarding fins are positioned towards the ends of twin-tip kiteboards or at the tail of surf-style kiteboards.
The initial use of the fin allows you to edge against the pull of the kite giving you the option to change your board speed as well as an easier change of direction.
Although not essential on twin-tip kiteboards, almost all production boards come with fin inserts as standard.
Fins on a twintip board normally range between 3.0-6.0cm and can give more or less grip as you turn in the water.
As a general rule, smaller fins will allow you to turn the board quicker into the direction you want to go, whereas larger fins will give you more grip and pressure against the water allowing you to hold more power when needed.
There could be anywhere between one and five fins on a wave board and a multitude of configurations.
Based on the idea of the sailboat keel.
Single fins have added stabilization and control on powerful, larger waves, although can lack the manoeuverability of other fin setups.
Twin fin setups are great for small waves, being fast and manoeuverable, but when put into tight spots on larger waves, they can become harder to control.
This type of configuration is often popular with Fish surfboards.
Thruster / Tri-Fin setups are widely recognized as the standard fin configuration for the majority of kite surfboards.
The thruster answers the shortcomings of the single fin and the twin fins configurations and gives you stabilization, control and manoeuverability in all types of surfing conditions.
Quad fin setups boast an extraordinary amount of holding power in larger surf.
You may think that having four fins would sacrifice speed by creating more drag, but this is not the case.
The both sets of fins are working together on the rail. Makers believe they create less drag than a board with a centre fin.
The manoeuverability isn't sacrificed either, with fins directly under your back foot, the quads are very responsive.
A Bonzer / C5 5-fin configuration normally has the addition of a centre trailing fin in the back.
The two front fins are typically small and oval shaped and designed to direct the water through the larger side fins allowing for more drive and grip from your board.
This type of setup is often used for kiteboard racing.
A Fin System is the name given to describe how a fin is attached to the base of a directional Surf Board. Below are some examples:
The F.C.S (Fin Control System) is a fairly new system, designed in 1995 by Australian Brian A Whitty, which allows for a wider choice of Fins to be fitted to a Directional Board.
A conventional Fin would be glassed-in to the board permanently, whereas an F.C.S System has a slotted box with an Allen Key fitting.
The Fin is secured in place using this method and is easily removed should a fin change be necessary.
The Tuttle fin box has straight sides and the root is a uniform 1.60 cm (.625″) and the “fit” is supposed to be quite tight on the sides.
The depth is set by the angles on the front and rear of the fin root.
The tuttle fin gets most of it’s support from the close fit between the sides of the fin root and the sides of the fin cavity in the board.
The “Deep Tuttle” configuration is the same width on the sides, but the fin root is much taller (deeper), measuring 7 cm (approx. 2 3/4″) at the same point on the root.
The Powerbox is a fin system using a root with both tapered sides and tapered front and back.
Primarily used in Kiteboard Racing.
When the tang (or base of fin) is clamped in the box with the set screw the tang is compressed horizontally.
This compressive force is dissipated by the trusses into the solid base of the fin.
The trusses act as I–Beams with their long axis running the width of the tang.
The long axis of the truss resists lateral loading on the fin during surfing keeping the base extremely stiff.
The use of Truss and I-beam technology gives the base of the fin a maximum stiffness to weight ratio.
This enables Futures to have 60% more base than plug systems while still remaining extremely light and stiff.
The maximum height of a fin is measured from the bottom surface of your board.
The hold of your surfboard increases with more depth but generally makes it harder to turn as well.
The shorter the depth, the more slide the board will have. 3-4 inch depth is normally standard on tri-fins.
The base is often referred to the length of the fin where it joins your board.
Increasing length adds forward drive, but can make it harder to turn.
The less length there is in the base of the fin, the shorter the turning arc will be.
Shortboard tri-fins usually have a 3.5-4.5 inch base.
Rake, also know as sweep, can be seen as the amount of the fin outline that is curved backwards.
It is the angle created between the back of the fin base and the offset of the tip of the fin.
The rake prominently affects the turning ability of the board.
The smaller the rake angle is (i.e. the greater the offset), the better the drive but less manoeuvrable the board will be.
The larger the rake angle is (i.e. the less the offset), the tighter the board will be able to turn.
Fins with little flex are more responsive and will have more speed and direct drive.
Fins with flex are more forgiving and easier to use.
Ideally a fin would have a stiffer base for drive and more flexible tip for release.
