The Naples Systematic Series – Second part: Irregular waves, seakeeping in head sea. (15th December 2019) - De Luca, F.
Abstract: The main aim of this study is to characterize the dynamic behavior of the Naples Systematic Series ( NSS ) in irregular head sea. A further aim of the study is to provide data to detect the influence of hull form on the sea-keeping performances in the planing and semi-planing speed range. The NSS derives from a parent hull that has shown to behave well in rough seas, characterized by high deadrise angles of the bottom at the bow, to reduce acceleration. All the models of NSS were tested in three different sea states and in Fr range from 0.515 to 1.197. The relatively high Froude numbers associated with the forms of the series make inappropriate the statistical analysis usually carried out to describe the behavior of the displacement ships. To overcome these unsuitableness, Cartwright Lounguet Higgins, extreme value and normal distribution fittings have been furnished for heave and pitch maxima and minima; gamma and extreme value have been furnished to represent acceleration in the centre of gravity and bow. Finally, a case study is presented to show a useful procedure for designer evaluation. Highlights: Seakeeping experimental tests in irregular head sea. Resistance in waves. Study of behavior of high speed craft in waves. Statistics on motion of planing hulls of Naples Systematic Series. Fitting of probability density function.