A structural element, usually made of wood or fiberglass, attached to the bottom of a surfboard to aid maneuverability. Fins were first introduced in 1935 by , who fastened a speedboat keel to the tail of his board. The modification, which prevented the board from haphazardly sliding down a waves face, led to modern surfing as we know it.
Perhaps more than any other factor, its the number, angle, base width, and rake of a surfboards fins that determine how it rides. In the late 1940s, 泭stuck two parallel fins on the bottom of his board, creating a looser, more squirrelly ride. Three decades later, in 1981, Australian 泭assembled the first thruster setup by adding a third fin behind two forward fins, combining the best of single- and twin-fin approaches. Today its by far the most popular design.
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