Line design and optimization for polar expedition cruise ships with transoceanic voyage characteristics

With the rising interest in polar tourism, polar expedition cruise ships are attracting attention as a novel, promising ship type with typical transoceanic voyage characteristics, i.e. voyages involving both open water and ice regions through flexible routes. With the carbon-neutral requirement, especially in the polar areas, it is urgent to achieve low carbon emissions for cruise ships. This study investigates the voyage features of typical routes representing typical operational scenarios of the expedition cruise ships by surveying the statistics of various routes. Then, it develops a multi-step line design and optimization frame to achieve multiple objectives such as the minimum overall resistance and delivered power gradually. A case study is investigated to describe the process. The optimum results are discussed with four typical representative hull forms. At first step, at least 8.36% reduction for overall resistance can be achieved. Further improvement can be achieved at second step with an extra reduction of delivered power up to 1.68%. Furthermore, after third step analysis, it is necessary to provide an additional 2.2% or more of the propulsion power to maintain the navigation in the ice region at the service speed. Then, a set of regression formulas have been obtained during lines design and optimization by investigating the open water and ice regions with their combinations. In short, this study provides a reference for assessing the ice loads and depicting the transoceanic voyage features in polar expedition cruise ship designs.