Air is often used as a lifting element, to support and sustain a high speed craft, by generating an aircushion at high pressures. The air can be used also as a lubrication system on a faired bottom of a fast or slow boat, by generating artificial cavities, which reduce the boat viscous resistance. Russian researchers, at Krylov Institute of St. Petersburg, studied these phenomena since the sixties and allowed the development of such typology of ships, both fast and slow.
After a short explanation of the basic principles which define the supercavitation on a hull bottom, and after having defined the most important physical variables which influence the cavity growth, a series of results obtained on three ACS (Air Cavity Ship) models, tested at DINMA facilities, are shown.
The results obtained are discussed and a series of considerations regarding the recent development of these hulls are made.
