Vertical Motion Assessment in the Concept Design Stage of a Small Cruise Ship

The traditional approach to cruise ship concept design has always focused on satisfying constraints related to propulsive and strength issues, shifting the estimation of other attributes to more advanced design stages. This is the specific case for the motion induced comfort onboard a vessel, a quantity related to the vertical accelerations onboard. The literature does not provide examples of simple formulations that can be used in concept design to estimate vertical motions. To this end, the present work provides a set of simple formulations for estimating vertical motions onboard cruise ships in the concept design stage. Starting from an initial database of 58 hulls, dedicated seakeeping calculations have been carried out for several sailing conditions. As a result, regression formulae have been generated for the TRFs of the vertical motions, providing useful instrument for the concept design predictions of a vessel. This work presents the database and the calculations performed to determine the TRFs, together with the process employed to obtain the simple regressions. An example performed on a vessel not included in the initial database underlines the good approximations provided by the obtained regressions.