Prediction of Porpoising Instability of Planing Boats Based on RANS Simulations

In the present paper a stability analysis of the porpoising problem for a luxury yacht is proposed. The approach is based on a linearization of the sink and pitch motions of the boat around the center of gravity (CG. The stability coefficients, usually calculated by means of simplified approaches, are now evaluated through unsteady RANS simulations, in order to perform a deeper and more close to reality investigation of this problem. Two in-house numerical codes have been employed, both based on a finite volume method with a level set approach, in order to cross-check the results for the lowest speed. A total number of four speeds, spanning from 18 to 34 knots, has been studied and an encouraging porpoising analysis is finally discussed.