Computational fluid dynamics analysis on the course stability of a towed ship

Due to the highly complex phenomenon of a ship towing system associated with the presence of a dynamic nonlinear towline tension, a reliable investigation allowing for an accurate prediction of the towed ship’s course stability is obviously required. To achieve the objective, a Computational Fluid Dynamic simulation approach is proposed by investigating attainable and precise course stability outcomes, whilst a hydrodynamic description underlying the rationale behind the results is explained. Several towing parameters such as various towline lengths and tow point locations with respect to the centre of gravity of the barge have been taken into account. Here, tug and barge is employed in the simulation as the tow and towed ship, respectively. In addition, a towing velocity is constantly applied on the tug. The results revealed that the course stability of the towed ship increases in the form of more vigorous fishtailing motions as the towline length subsequently increases from 1.0 to 3.0. Meanwhile, the increase of tow point location from 0.5 to 1.0 leads to a significant improvement in the course stability of the towed ship, as indicated by the reduction of the sway and yaw motions by 227% and 328%, respectively. It is concluded that the increase of tow point location is a recommended decision to achieve a better towing course stability for the barge.