Instead, the lower part of the hulls have skegs typical for a beach catamaran. The lower part of the hulls have skegs typical for a beach catamaran. Many have steering gear or tracking aids in the form of rudders or skegs. Originally, a propeller was installed between two skegs under the transom. The vessels had four screws, with the two outboard screws mounted in skegs. Some Skegs may be more effective at countering pitch, roll and yaw. Skegs have been used to improve the directional stability of seaplanes. Originally, skegs were installed to decrease slippage on a wave face.