No abstract

A novel empirical method to study wind-assisted cargo ships is presented. The physical ship model, including propulsion units, interacts in real-time with a numerical sail model during free-running tests. Loads from the (virtual) sails are applied on the physical model using a cable-driven robot. All loads components except heave are applied with high accuracy and repeatability. The method is described thoroughly, and applied to investigate the benefits of wind assistance on a 190m bulk-carrier, equipped with four rotor sails. Key performance indicators for wind assistance are established when sailing in steady wind profiles of various directions and velocities, and a propulsion analysis is performed. An important conclusion is that the increase of hydrodynamic resistance due to heel, leeway and rudder (that balance transverse sail loads) is rather limited for this ship, except when sailing close-hauled in strong winds. It is also demonstrated that experiments in a unsteady (virtual) wind environment can be successfully conducted. The effect of turbulence on the motions of this ship are found to be very limited. The conclusion discusses the other types of studies that can be enabled by this novel cyber-physical empirical method.

The field of sea based modern shipping activities is constantly seeking for its improvements to achieve the economically justified operational patterns. In the same time, the sea transportation activities also need to satisfy currently imposed and, as well as, upcoming in the near future, safety and ecologically friendly footprint characteristics when it comes to the emission of greenhouse gasses and hard particles [1]. Fulfilment of the stated requirements consequently asks for the determination of certain vessels operational parameters such as the total resistance of a vessel which estimation is frequently carried out for predefined calm and deep-water environmental scenario. Current work is dealing with investigation of the total resistance parameter in calm and deep water for the preselected types of the trimaran ship hull configurations. The total resistance is estimated according to [2] recommended procedure through applicability of the robust and reliable method which is capable to address the problem of wave resistance prediction in calm and deep water. The method has origin in ordinary and modified Michell thin – ship wave theory by considering the viscous effects [3]. The differences between the utilized theories are discussed from the qualitative and quantitative point of view of the obtained results in comparison to the open source available theoretical experimental data and from the perspective of common engineering practice. Finally, based on the above description, the performed total resistance studies are used as a base for formulation of the optimization procedure which may be used in the trimaran vessel preliminary designs in the range of the forward speeds commonly expected during the normal operational life of the investigated trimaran vessel.