Numerical simulation as a powerful design tool for the propulsion and manoevring performance prediction of pleasure craft

Although a more and more increasing industrial interest regarding the production of effective and safe propulsion systems for high performance craft has been shown in the last years, some important propulsive aspects, as the manoeuvrability of planing boats, are not yet widely covered in literature. In order to respond to the growing demand of high quality marine systems by the pleasure boat market, University of Genoa has recently begun to validate its numerical codes, originally developed mainly for naval vessels applications, also for the investigation of the planing craft behaviour. In comparison with the displacement ships applications, the simulation activity carried out in this new research field has required further efforts to develop an effective numerical methodology for the computation of the manoeuvrability dynamics of the planing hulls. The paper deals with the simulation approach adopted by the authors for the development of a planing craft simulator, realised in a modular structure and where each module represents the dynamics of the several components involved in the propulsive phenomena. Thus the hydrodynamic characteristics of the planing hull, the engine behaviour, the propeller or waterjet performance, the rudder and the control system dynamics are implemented in this simulator. As an example, two applications (for which some data from sea trials were available) are presented, i.e. the 34 meters yacht “Leopard 34”, by Cantiere Navale Arno, propelled by three waterjets, and a smaller planing boat with a length of about 40 ft, by Azimut-Benetti S.p.a, with a conventional configuration with twin screw propellers and rudders. The aim of the work is to develop a complete propulsion simulator to be used in the design phase of the boat, able to provide useful information about the selection and the design of the several propulsive components.