Mast device for aerodynamic improvement of sail boats

The creation of the Guide Vane system comes as a direct response to the need for a competitive edge present throughout the sailing world (amateur and professional). This competitive edge can be expressed both as the capability to sail faster (i.e. larger net forward force acting on the boat), and to cover a more direct route towards the desired target (i.e. the finish line). The Vanes working principle is entirely based on the weakening of the adverse pressure gradient present in the rear section of the mast. It achieves this by decelerating the flow traveling through its slots (increase of static pressure). This aerodynamic mechanism induces a reduction of the separation bubbles created by the mast's wake (constant detrimental effect on the boats performance). This provides two beneficial effects: first, the reduction on the amount of disrupted flow over the Main Sail, which in turn leads to a beneficial collateral impact over the entire Main+Fore Sail System (greater group Lift generation, and the capability of the boat to fly closer to the wind); secondly, the reduction of the mast Drag (and hence increase of the net forward force acting on the boat). These binary slots have two degrees of freedom (height and incidence), allowing a tailored setting for specific sailing conditions. Extensive wind tunnel work was carried out using Force/Moment transducer, Pressure Sensing and Tufts Visualization methods to correlate the aerodynamic behavior of the Mast with and without the Vane's. Drag reductions of 20% to 50% were recorded, within specific operating regions. The Tufts system provided a visual proof of the reduction of the mast's wake. The Pressure system allowed the identification of the velocity profile of the wake. The Vanes System drag reduction effect "activates" at a critical speed, depending both on the Slot's Height and Incidence (Vcrit=10.6m/s for slot's Height=13mm and Incidence=90°). Both unwanted Aeroelastic Effects and Stall (high speed + low incidence conditions) were suppressed, due to the presence of the Slots. © 2004 by L. D. Gomes, K. Kontis.