Vara System - Variable aspect rudder assembly - US Patent # 5791277

THE CONCEPT

The design of a typical inboard rudder is limited because of the diameter of the rudderstock. For a given rudder size and it's associated forces, the rudderstock must be a certain diameter, which usually means the rudder must be thicker than is optimum. The VARA system allows the use of both a high-aspect planform and a thinner section to maximise the the lift-to-drag ratio and to minimise drag, because no rudderstock needs to fit inside the blade.

The system consists of a drum that turns on upper and lower bearing races with a daggerboard-style slot into which the rudder fits. The rudder can be raised to reduce wetted surface when sailing downwind or in light air. The blade can be quickly and totally removed for trailering. Adjustment plates on the top of the drum permit the rudder to be swept fore-and-aft to optimise the helm's "feel" and loading. For example, in light air, sweeping the rudder aft increases feel and helm pressure; in heavy air, having zero or a small forward sweep eases the helm pressure.

The plates on the top can be made to allow the rudder to be canted from side-to-side to bring it more vertical when the boat is healed, thus increasing the blades efficiency, a feature that can be advantageous in offshore distance racing.

We have created a hydrodynamically optimised, fully adjustable system for inboard rudders.

The Vara System is fitted as standard on many Henderson Designs. It has also been supplied and retrofitted to an SR 33, Beneteau 10m and Quest 30 and enhanced performance significantly. On site installation is made simple by Soca supplying a fully finished, completely mounted system.