The Second Generation of Unmanned Surface Vehicles: Design Features and Performance Predictions by Numerical Simulations

Paper presents the basic principles and the main characteristics of an innovative family of Autonomous Surface Vehicles (ASV). Their design features a new type of unconventional SWATH hulls forms optimized for low resistance at high speeds and excellent seakeeping properties. The concept design is presented in his major aspects by means of the results of the numerical hydrodynamic simulations used to optimize and verify the performance of the vehicles both in calm waters and in waves. Specific numerical tools have been developed to drive the design with accurate seakeeping and resistance predictions process and automatize the parametric optimization of the hull shape. The result of the integrated design procedure is a new generation of small-medium sized ASVs with reduced propulsion requirements (up to 30% with respect to a conventional SWATH hull form) and superior seakeeping ability: 1/2 heave amplitude and 1/3 pitch amplitude with respect to an equivalent catamaran over a wide range of wave lengths. Two design examples are finally given: the first is a relatively small (6m long) vessel for the autonomous launch recovery and recharging of AUVs. The second vessel is a hybrid Hydrofoil-SWATH, capable of reaching a top speed of 120 knots in the foil-born mode, at which four specially devised and studied supercavitating hydrofoils are used to sustain the vessel in combination with the wing in ground effect of the specially designed superstructure.