Everything You Wanted to Know About Surfboard Fins But Were Afraid to Ask
Fins 101
A surfboard fin is a hydrofoil (think fluid mechanics, if you can) which is attached perpendicular to the board at the bottom of the tail.
The lateral lift the hydrofoil fin creates provides directional stability and control through steering with foot pressure. The lateral lift is opposed to oncoming water as a surfer rides a breaking wave. It also stabilizes the surfboard's movement forward or trajectory. The fins and the bottom of the surfboard provide the rider control surfaces.
Surfboard fins were a huge advancement over the maneuverability, control and performance of early surfboards. Their engineering, design and material improvement has reached a renaissance in recent years.
Surfboard fins are outfitted on boards in various quantities and configurations. They are now available in many sizes, shapes, and materials (see Fin Materials), all designed to customize your ride. The earliest fins were created and used in Hawaii, where the original surfboards were also invented. Fins are used on all surfboards.