An experimental comparison between different artificial air cavity designs for a planing hull

For several years it has been studied how to obtain resistance reduction by means of air injection under the hull. The most studied applications are essentially slow hulls; however, significant results in planing hulls can be achieved. Unfortunately, for this kind of crafts, there are very few experimental data. This study has been performed to compare different cavity shapes, obtained by modifying a mother-hull of a high-speed planing yacht. The design has been obtained with the idea to use the natural low pressure under the bottom of high-speed crafts, in order to stabilize an air-layer instead of the traditional air-cushion. The experimental tests were carried out in a towing tank by varying numerous parameters, including the model speed and the flow rate of air. Results and influence of geometrical and physical parameters are discussed.