(5th Report) A Study on Evaluation of Seakeeping Performance for Passenger Ships : Measurements of Vomiting Ratio in Long and Short Voyages and Occurrence of Parametric Roll Motion

Abstract

The authors measured ship motions and the vomiting ratio of passengers on a cruise ship in three months voyage and on a small ship in short voyage. The results demonstrate that it is possible to estimate the vomiting ratio in fairly good accuracy by the authors' estimation method on the bases of O'Hanlon's experimental data. In the measured data of the small ship, it is observed that the period of rolling is twice as long as that of encounter in following and head seas. Using a numerical simulation using the database of restoring moment varying in wave, the occurrence of parametric resonance is confirmed numerically.