Seakeeping Analysis of a Medium-Speed Twin-Hull Containership

The use of twin-hull ships for high-speed passenger and carpassenger transportation is widespread while their potential use for high-speed cargo transportation was estimated as limited. In this paper the seakeeping performance of a medium-speed twin-hull container ship is presented. The hull form underwent a hydrodynamic optimization at the School of Naval Architecture and Marine Engineering of NTUA both for resistance and seakeeping, within the EU project “CARGOEXPRESS.” The seakeeping analysis was performed by applying numerical tools and also by performing a series of experiments in the towing tank of NTUA. More specifically, calculations have been performed using three different approaches of varying complexity and theoretical consistency. The first is based on a strip theory adapted to twin-hull vessels. The second, a fully 3D approach, is based on the distribution of pulsating Green sources over the wetted surface to calculate the velocity potential, using appropriate correction terms to account for the forward speed. The third also fully 3D approach is based on the distribution of Rankine sources over the wetted and the free surface, to satisfy the linear free surface condition. The numerical results are compared with each other and with experimental ones measured in the towing tank of NTUA using a 1:24 scaled model of the hull form. The validity of the applied approaches is discussed.