Page "Fin" Paragraph 13

A fin configuration with fins near the edge of the board stabilizes and contributes lift during turning maneuvers, which contributes to the board's ability to " hold " during turning maneuvers.

Rail fins are often seen in addition to a central fin, but can be used without a central fin as well.

Some of the most popular multi-fin configurations use two rail fins ( a " twin-fin "), two rail fins plus a similar-sized central fin mounted further back ( e. g. a " Thruster "), or four fins ( a " quad ").

Rail fins are more or less engaged by the rider's heel and toes as they lean in the desired direction of their turn.

As the rider does so, an " inside " rail fin sinks deeper and its angle of attack is increased, as is its lift-induced drag.

Rail fins also add lift ( known as " drive ") in trim and with greater holding ability, enable steeper wave faces to be ridden and higher speed " down the line.