Comparative study of various strip-theory seakeeping codes in predicting heave and pitch motions of fast displacement ships in head seas
The study focuses on a comparative investigation of three seakeeping codes based on the ordinary strip method: the open-source code PDstrip, the commercial code MaxSurf and an in-house code earlier developed at CENTEC. All programs were applied to two fast displacement ship forms upon head seas: a mono-hull and a catamaran, for which experimental data from model testing were available. In the latter case, an assumption about negligible hull-to-hull interaction, acceptable in head and following seas, was exploited. The peculiarity of these vessels is reaching Froude numbers up to 1.14, which increases possible uncertainties caused by the strip method assumptions. All codes are linear and formulated in the frequency domain. Heave and pitch RAOs have been compared, computed whenever possible both with and without transom terms activated. The observed differences between the three codes and from the experimental data motivated an analysis of the computed added masses and damping coefficients.