Windsurfing fins have five key features: outline shape and length, profile and width, rake angle, flexibility and twist, and fin box system. Most of windsurfing fins are made from G10 / fiberglass / carbon materials.
The system incorporated in a fin determines the type of fin and its purpose. Normally there are four types of systems used in designing windsurfing fins.
1. Tuttle Box: A tuttle box fin system comprises of aligned sides and a fin base which measures 1.60cms. The tuttle box fins fit snugly on the sides and its front and rear angles determine the depth of the fin. One of the variations of the tuttle box system is the Deep Tuttle system. In the deep tuttle system, only the depth of the fin base increases with the remaining specifications (front and rear angles and width) being constant. The deep tuttle fin base usually measures about 7cms in depth, about 2cms deeper than the normal fin depth in a standard tuttle box system.
Tuttle box systems are usually used for wide race board fins. Tuttle box fin systems are considered the strongest fin systems. The deep tuttle fin system is used for racing surf boards. The standard tuttle system fins are used in slalom windsurf boards.
2. Power Box: Unlike the tuttle box fins with aligned sides, the power box system fins consist of tapering sides as well as at the front and rear ends.
3. Trim Box (often referred to as a Power Trim box): The fin box system fins also consist of straight sides along with plastic spacers. The spacers may be placed either in front or at the back of the fin. These spacers enable free movement of the fin in the fin box.
4. A and E boxes: are the oldest styles. The fin is mounted from the bottom. The two systems look the same, except that the E base is a little deeper. They are weak, but offer adjustment, so they are still used on some wave and convertible boards where strength is less important than exact fin placement. Widely used on older boards.