How Split Fins Work

Five-step diagram of how split fins work

Dive center shelves are stocked with a broad spectrum of fins of various shapes, designs and stiffness, and one of the more interesting trends in diving over the past 10 years has been the development of split-fin designs. Unlike the standard “paddle” fins that consist of a single rigid or semi-rigid blade, the split fin sports a lateral split, extending through the majority of the blade length, which is designed to enhance the efficiency of the fin.

According to designers, a split fin allows the two blades to assume a propeller-like configuration during the power stroke. The force of the blades against the water causes them to bend into a foil shape, which reduces the drag while increasing the suction or lifting force to enhance propulsion (see illustration).

© Alert Diver — Q4 Fall 2009