Surfboard Fin Facts

The original surfboards were created and used by the native people of the Hawaiian islands and were gigantic boards called olos. These original surfboards were used to ride straight into the shore. Advancements in the design of surfboards in the 20th century -- including the addition of fins to the bottom of the boards -- enabled surfers to do much more than ride a wave in a straight line.

  1. Fins

    • A surfboard fin is usually positioned beneath and to the rear of the board. The number of fins can range from a single fin to to as many as five. The use of fins beneath the surfboard was first recorded in 1934 by the surfer Tom Blake, who decided to add a keel to the base of his board after observing the use of the keel under a boat, Surfing Handbook reports. The initial keel used by Blake was 4 inches deep and around 1 foot in length. The curved shape of the modern surfboard fin was introduced in the 1940s by Bob Simmons. In the 1980s, three-fin surfboard designs were introduced followed by a five-fin design released in the 1990s. The flexible fin design was created by George Greenhough and was based on the fin of the blue tuna.

    Turns

    • The design of a surfboard fin is created for the specific needs of a rider. A deeper fin allows more maneuverability and sharper turns. The fin is measured from the base of the surfboard to the tip of the fin. Each fin is curved to create an angle measured from the base of the surfboard to the tip of the fin. The distance the fin curves backward is known as the rake or sweep angle. A smaller rake provides less maneuverability but increased speed, Surfing Waves reports.

    Removable Fins

    • Some surfboards feature removable fins. Each fin of a removable fin has a fin plug that fits into a slot on the base of the surfboard. The fin is held in place in the fin box by a screw that is tightened after the fin is placed into position. Glassed-on surfboard fins are not removable.

    Base

    • The base length of a fin is the length of the fin at the point it meets the surfboard. An increased base length adds greater speed but reduces the ability to turn sharply, according to Surfing Waves. By contrast, a shorter base length adds greater maneuverability to a surfboard. The increased ability to make sharp turns was popularized by Australian Mark Richards, who used flexed fins to become world champion from 1979 to 1982.