Surrogate Models for Propulsive Performance in the Feasibility Study of Cruise Ships

Propulsive issues are of utmost importance for determining a successful cruise ship design. Estimating the propulsive power and associated propeller revolutions needed in trial conditions is one of the key aspects for writing the contracts between yards and shipowners. Then, it is relevant to be capable of predicting the propulsive performances of the vessel in all the phases of the vessel design. In the present work, the focus is on the feasibility study of the vessel, when main dimensions should be selected before starting any other consideration on the hull form, internal layout and machinery equipment. Therefore, the study proposes the generation of surrogate models for the propulsive characteristics of the ship as a function of the vessel’s main dimensions. Starting from an initial design space discretised with a Box-Behnken methodology, dedicated calculations have been performed by employing validated empirical-statistic methods on each member of the design space. Relevant quantities, like absorbed power, propulsive efficiency and optimal propeller characteristics have been collected in a database to perform a multiple linear regression analysis. The obtained models have all high quality of fit indicators, highlighting the good fitting performances of the regressions. As such, the study provides a good instrument for designers, allowing for estimating propulsive performances in the feasibility study of ships, before the concept design phase begins. Further improvements could be achieved by extending the initial design space.