Surfboard Fin Types

December 02, 2010

Fins are without a doubt one of the most important aspects of surfboard performance. Before the first fins were attached to boards in the 1930s, surfers had to drag a foot in the water in order to turn — which is great for developing stellar balance, but not so great for carving up a wave.

Fins impact the stability, responsiveness, speed, and general feel of your surfboard. So if you want to take your surfing to the next level, it’s critical that you understand how fins work and how various fin types can influence your surfing.

Fin Categories

Surfers also have two options regarding the type of fins found on their board: Removable, and glass-on.

Removable Fins

The majority of boards these days have glassed-in fin boxes or slots into which fins slide with screws used to hold them in place. This allows you to switch fins out easily and remove them for travel. Despite the convenience, however, some shapers and expert surfers are convinced that removable-fin systems limit board performance.

Glass-on Fins

A glass-on fin is laminated to the surfboard. For that reason, attaching the fin to the board is an art in itself. The amount of cloth used to set the fin in place, as well as where the material is built up at the base of the fin and how the area is sanded and glassed can all impact board performance. Some surfers think that glass-on fins enhance their surfing and make the board and fin feel more integrated. Most pro surfers have fins that are glassed-on.

Shape

The shape of the fin plays a big role in how it will function:

Base length: A longer fin base results in more surface area and will make turns stronger, while a fin with a shorter base pushes less water and allows for a shorter turn radius.
Height: A taller fin will have more contact with the water and provide more control, while a shorter fin will make it easier to slide and steer the board from side to side.
Rake: This refers to how far back the fin curves in relation to its base. A fin tip that has a large offset from the base is said to have a small rake and will provide more board speed and stability, but won’t allow the board to turn as easily. Conversely, fins with a large rake and small offset will facilitate a tighter turning radius, but won’t offer as much stability.
Foil: Fins are tapered so that the leading and trailing edges are much thinner. Foil refers to the thickness of the fin in the middle, and effects how water flows around the fin. The more foil a fin has, the more lift it will provide. However, greater foil also equals more drag and, in turn, less speed. A lot of smaller side fins tend to be single foil, meaning they’re flat on the inside and foiled on the outside.
Other features: There are also numerous fin shape modifications that have yet to be widely adopted, such as: Tunnel fins (hollow tube running through it), bullet fins (bulbous base), winged fins (small winglets on the fin), concave fins, and curved fins — all of which affect board performance.

Positioning

Subtleties in how a fin is positioned on the board also impacts how a board will surf:

Placement: Fins can be placed in a number of areas on the tail section of the board; and an experienced surfer can feel even very minor changes in position. Optimal fin placement depends on wave type, board shape, weight, and size, as well as the mass, ability, and style of the rider. As a general rule, moving a center fin forward on the board will allow you to make a shorter arc. Having it too far forward might make the board too aggressive. Placing fins farther back on the board usually provides more hold, allows for a longer arc, and will work better for bigger waves and barrel riding. For boards with multiple fins, a more spread out fin cluster will also result in a longer arc. A more compact cluster will permit a tighter turn.
Toe: This is the angle at which the fin sits relative to the center stringer of the board. The more the leading edge of the fin is angled in, the more water pressure it will create and the more responsive the board will be. Center fins have no toe-in, whereas most side fins do.
Cant: This is the angle of the fin relative to the bottom of the board. A fin with no cant is set at 90 degrees to the board. Canting a fin outward, toward the rail, makes the board more responsive, but will also slow it down.

Flex

How much a fin flexes and the way it flexes are often overlooked characteristics that can have a huge effect on board performance. A softer fin tends to be favored by lighter surfers in small waves, whereas heavier surfers generally prefer a more rigid fin — especially in larger waves. In addition, the quality of the flex, the amount of torsional flex, and how quickly a fin rebounds can also have an impact on how a board feels.

Hot Tip: Safer Fins

A significant number of surfers have suffered puncture wounds and eye injuries from standard surfboard fins — either from their own board or as a result of collisions with other surfers. In response, a few fin manufacturers began producing fins that have a rigid body, but a soft urethane edge. Some surfers swear by them and others don’t like the way these safer fins affect board performance. Functionality aside, soft edge fins have helped cut down on the number of surfing-related stitches and eye surgeries.

Number of Fins

The number of fins on a board, where the fins are placed, and the total surface area of the fin(s) can have a significant impact on board performance:

One fin: Single fins are placed in the center of the board and are mostly seen on classic longboards. In general, a single-fin longboard is better for nose-riding, as it will better track in a straight line. Single fins are usually set far back on the tail to prevent the board from spinning out.
Two fins: Twin fins have one fin placed on each side of the tail with no center fin. This is a very popular fin configuration on traditional “fish” and modern shortboard shapes with wider tails. The twin-fin configuration makes a board very maneuverable and will ordinarily feel faster and looser. However, boards with two fins are usually not preferred in bigger conditions or for barrel riding.
Three fins: A three-fin configuration utilizes a center fin and two smaller fins placed on either side. Three-fin setups are commonly referred to as either a “2+1”, in which the center fin is larger, or a “thruster”, in which all three fins are similar in size. Either way, boards with three fins tend to be the most versatile, as they blend the hold of a single fin with the responsiveness of twin fins.
Four fins: This configuration is also known as a “quad” or a “twinzer.” In a quad-fin configuration, the fins are a little more spaced out and the lead fins are toed-in a little more than the trailing fins. In a twinzer configuration, the lead fins are smaller than the trailing fins. The fins are also closer together and have similar toe-in angles. In general, the quad set-up is known for speed and a looser feel that enhances board maneuverability.
Five fins: A five-fin pattern is similar to either a quad or twinzer, but has the addition of a larger center fin. As a result, boards with five fins aren’t as fast or loose feeling as quads. Instead, they are more stable. Some surfers are also experimenting with six or more fins on a board.

Trial and Error

Since there are so many variations of board shape and size, it’s difficult to say which fin types and configurations will work best for your weight and surfing style, and the type and size of waves you surf most. As a result, even if you’re happy with your current fin set-up, it may be worth experimenting with some different variations to see if there’s a better option for you. If nothing else, trial and error will make you more aware of your equipment and will help to improve your surfing — which in turn, equals more fun!