Hydrodynamics of Surfboards by Rainer Butler-Schafer
In the anatomy of a surfboard, fins are the crucial
this causes the board to plane rather than pushing
part that makes everything work together. A board
water back with the tail. Creating a surfboard fin
without fins would slide around because it wouldn’t
that can hold onto the wave during hard turns, flow
have anything for the board to pivot around or to
through the water and gain speed, but also release
stabilize it. The fin’s sole purpose is to help the board
when the surfer wants to perform an aerial trick, is a
track well and prevent it from sliding around, as well
daunting task.
as making sure that the board is responsive to the surfer’s feet when it turns. The two elements acting on surfboard fins are lift and drag. An upward lift can be generated if the end tip of the fin is on the outside of the base of the fin, making the fin slant just enough to create lift. Lift is used on a surfboard to gain what surfers call “drive” and “hold,” referring to the fin’s ability to gain speed, and the fin’s ability
Surfboard Fin Showing Thrust, Lift, Weight, and Drag Forces
to make the board stay locked in on the wave when performing sharp and aggressive turns. Lift can also
There are a few different types of drag acting on
push the board, making the ride smoother because
the surfboard fin: skin-friction drag, interference drag,
