Surfboard Fin Guide
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This is a Guide to help you understand the physics behind how a fin works, ultimately helping you decide which fin would be best for you and your surfboard.
Do fins really make a difference?
Yes, fins make a huge difference. Fins provide direction, acceleration and allow you to apply power into your turns without loosing control. Different fin sizes, templates and foils can also change the way a surfboard will perform.
A fin is the part of the surfboard that sits in the water, similar to a rudder on a boat. The fins on a board provide stability, maneuverability, and shred-ability. The fin has played an important role in advancing the design and performance of the surfboard to new levels. They have progressed into fine tuned pieces of machinery. There are many designs, shapes, sizes, and manufacturers; making the fin the most important surfing accessory.
Glass On fins are permanently connected to the surfboard through fiberglass construction. This type of fin was mainly used on older model surfboards. Glass on fins can be broken easily and are hard to repair. Surfboards with glass on fins are difficult to travel with.
In the early 90’s, Removable Fins were dreamt up as a way to improve surfing. Removable fins have important characteristics. They make traveling easier, provide options for varying surf conditions, and give the surfer the opportunity to change the overall performance of their surfboard by using a different fin template.
Curious about installing your new fins? Not sure how, and don’t want to mess it up? Watch our tutorial over here.
Surfboard Fin Types
Single – The single fin setup is the original setup. The first surfboards with fins, were rode with a single fin, which was usually long and wide. This gave a surfer control of the board with only one fin. Ideal for point break waves, drawn out turns with larger arc and an over all cruisy feel.
Twin – The twin fin setup is a board with two fins that sit parallel, and are the same size, which provides extra speed and finer turning. Commonly found on fishes or boards designed for smaller, mushy surf. Great for down-the-line surfing, as opposed to top-to-bottom.
Tri (Thruster) – The most common fin setup, which consists of three fins of the same size, two parallel fins, and one in the middle sitting slightly back further towards the tail. This setup is used by the worlds best surfers and most popular for ripping waves.
Quad – This setup consists of four fins, two on each side, and provides more speed because there is no center fin. Quad fins are great for surfing steep waves, when its crucial to have two fins in the water for extra shred-ability. Great for down-the-line surfing. The surfboard also tends to release easier in top-to-bottom turning situations. Bigger fin sits more towards the nose, smaller towards the back.
2 + 1 – This setup is two small fins parallel with one larger adjustable fin in further back. Most commonly found on performance driven, longer boards. The two side fins help you turn sharper, and hold you higher in the pocket in steeper waves.
Twinzer – This setup is similar to a quad fin setup. Four fins total, the back two fins are much larger than the front two fins. All four fins have much more canter *(link to glossary) than a traditional Quad setup.
Bonzer Keel – Bonzer fin setup is very different. The bottom contour of the surfboard will have a double vee concave out the tail, combined with either three or five fins. Most common Bonzer setups include a larger back center fin, with two smaller trailer fins on each side. Bonzer fins drive the surfboard beyond its natural arc. “The Bonzer feel is essentially that of an enhanced single-fin, very sure of itself in the pocket and on the rail, and very tail-based.” Nick Carroll, Surfline.com
Longboard Fin Templates via Captain Fin Co.
Flex Fins – “Flex fins work great in everything from short little stubbies to mid-lenghts, to big old noseriders. These guys create little to no drag resulting in maximum trim. The more racked back the fin is, the wider the arc of your turn will be and the more upright templates will have a much tighter turn.” -Captain Fin Co.
Raked Fins – “Swept back outlines and a sleek look. Rake fins add performance and maneuverability to logs compared to pivot fins. A favorite among pintail and pulled in tail loggers. Work in everything from ankle biters to slightly overhead juice. Points, pits and beach breaks; Raked Fins can handle it.” -Captain Fin Co.
Pilot Fins – “The go to outline for the noserider elite, Pivot Fins have a vertical full outline with a wide base. They are designed to slow you down and keep the tail in the water while you are on the nose. Best in square tail logs, but add a classic feel to any log. Best in surf head high and below.” -Captain Fin Co.
Sweep – 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 producea longer turning arc, less sweep offers a tighter turning arc.
Flex – Referring to the distortion of the fin from its original shape caused by lateral pressure during a manoeuvre. Flex influences the response characteristics of a fin. Fins with little flex (stiff) produce instant response, speed and drive. Fins with more flex are more forgiving and offer a whipping sensation.
Cant – Referring to the angle of the side fins measured from a vertical line perpendicular to the flat bottom surface of the board. Cant has a direct effect on acceleration and maneuverability. Less cant produces faster acceleration and a stiffer feel. More cant will increase manoeuvrability and gives the board a loose feel.
Rake – The part of the back of the fin where it curves up from the bottom to the tip.
Tip – The top part of the fin or the furthest part of the fin in the water.
Materials (via FCS)
The material determines flex: flex = projection, projection = speed, speed = control.
”– Futures Fins
Performance Core- material and construction is designed to deliver the feeling of a traditional fiberglass fin with the added performance of reduced weight. The RTM (Resin Transfer Moulding) process produces a lightweight fin with remarkable flex, a smooth feel and an impressive aesthetic.
Composite Core – construction combines the Resin Transfer Moulding (RTM) process with a moulded glass and resin core insert to produce a lightweight fin with superior tip flex. The core insert increases the overall thickness of the foil ensuring hydrodynamic efficiency, a stiffer base and dynamic flex response through the tip.
Performance Glass – material characteristics and flex pattern are identical to traditional fiberglass fins offering a stiff base with subtle responsive tip flex, amazing aesthetics and proven durability. PG fins are the perfect transition fin for surfers moving from fixed fins to the convenience, accuracy and performance of FCS.
Glass Flex – has been formulated to replicate the flex and memory properties of hand layered fiberglass. It’s advantages over other composite fin materials include stiffness, a more positive flex pattern (nice tip flex, little base flex) and remarkable flex memory. The precision of the injection moulding process ensures the highest accuracy in geometry in each fin produced.
UltraLight – developed by FCS to create the lightest possible fin with superior flex properties while ensuring strength and foil accuracy. By minimizing weight without sacrificing response of flex and strength, Ultra-Light Epoxy is our lead construction process delivering the ultimate in performance.
Referring to the shape and geometry of the inside and outside faces of the fin. Foils directly affect the flow of water over the surface of the fin. Different foils create variations in water flow and have a direct link to the overall performance of the fin and the board.
A well designed fin does more then keep you from spinning out. The degree of foil – the curved cross section of the fin, along with the angle (how the fin tilts in relation to the bottom of the board), toe and other factors can add different dimensions to the feel of your board. The foils can create projection, torque, speed, maneuverability and release, and affect your board dramatically. Future Fins has created some of the most successful foils available, with decades of experience and testing, along with pro riders input, and input from the average surfer going into every series.
” -Futures Fins
Flat – A flat inside face combined with a convex outside face. The traditional flat sided foil offers an even combination of drive, pivot and hold and provides a very consistent, reliable feel over a wide variety of conditions.
Vector – Great for linking together turns, accelerating off your bottom turn and generating speed in slower waves.
Inside: A sophisticated hydrodynamic foil consisting of a convex outside face, a rounded leading edge and a concaved inside face. Inside foil increases the efficiency of water flow over the surface of the fin adding lift and reducing drag. The result is a fin with more options through increased hold and speed.
50/50 – A symmetrical foil used on all centre fins where both sides are convex. Even water flow on both sides creates stability and control.
Flat – Mimics the performance of a regular side fin offering fast transitions between turns, quick release and added hold on rail. (Ideal for boards with a wider tail, performance shortboards and boards with rear fins positioned close to the rail)
70/30 or 80/20 – Combines the performance of a centre and side fin offering increased speed, smooth rail-to-rail transitions and a consistent feel in a variety of conditions. (Ideal for all board types and rear fin placements)
50/50 – Mimics the performance of a regular center fin offering increased pivot with the added advantage of stability and control. (Ideal for all board types and rear fins positioned closer to the stringer)
PERFORMANCE, VIA FCS FINS
Drive – provides forward acceleration and helps maintain speed through turns. The amount of drive produced by a fin is directly influenced by the base length, material and the total surface area. Put simply; a larger fin with a longer base will offer more drive.
Pivot – refers to the length of the turning arc. Pivot is influenced by the sweep angle or rake, the foil and the depth of the fin. Fins with less sweep angle will turn in a tighter arc; fins with more sweep angle will turn in a longer arc.
Hold – is defined as the binding of the board to the wave. Hold is determined by flex and the overall fin template. Fins with more hold prevent the board sliding through turns, less hold allows the board to easily break free from the wave during turns; this is often referred to as ‘release’.
Fin Box – The box is what holds the fin to the board. The Fin Box is set into the foam of the surfboard prior to lamination creating a stronger bond with the board.
Template – The basic shape of the fin.
Base – The length between the leading and trailing edge where the fin meets the board. Base is primarily linked to drive. Fins with a longer base will offer substantially more drive and acceleration.
Depth – The distance the fin penetrates into the water. Depth directly relates to hold. The greater the depth the more hold, the shorter the depth the more a board will slide and release.
Surfboard Fin Sizing (by Surfer’s Weight in lbs.)
FCS thruster and quad sets are categorized by size. Each size category has an optimum wight range that can be used as a guide when choosing a fin:
Surfboard Fin Brands
FCS – The leader in the fin industry, FCS. “Today FCS has operations in several continents, with expanding global distribution networks statigically positioned to ensure the products are available all over the world. FCS continues to be dedicated to the design, manufacturing and marketing of innovative and quality surfing hardware and surf travel products.” A Guide To FCS Fins.
Futures – “Revolutionary thinking has always been behind leaps of progress – the larger the scale, the larger the culture, the larger the paradigm shifts that result. Future Fins is a company based on revolutionary thinking. A culture of experimentation, innovation and out-of-the-box thinking is combined with a sound base of technology, science and “under the feet research.”” – Futures Fins
Captain Fin Co. – Artsy, soul arcing surfing pirates; who make fins.
Rainbow Fin Co. – “One of RFC’s goals is to never produce fins on the basis of hype or make a fin lacking in performance. Working closely with surfboard manufacturers, team riders and
personally testing every fin design is the key to making our product line what it is today.” -RFC
Bahne Fins – Bahne Fin boxes are designed to provide versatile fin placement and allow fine tuning of the action of the board. The farther forward the placement of the fin, the stiffer the board will react and the farther to the rear the looser the board will be.
True Ames – Chuck Ames and the True Ames Fins team have been developing fiberglass and molded plastic fins since 1979.