On the Distribution of Cross Flow Drag over the Length of a Ship Moving Transversely

Abstract

It is of importance to evaluate the ship manoeuvring motion, such as the berthing in a harbour, the drifting behaviour of a disabled ship. A significant part of the lateral hydrodynamic forces acting on a ship will be due to cross flow drag, as the ship's drift velocity becomes relatively larger compared to the ahead speed. For the prediction of ship manoeuvrability at larger drifting angles, it will be required to estimate the cross flow forces accurately.In this paper, a calculation is given to the longitudinal distribution of the cross flow drag coefficient over the length of ship moving transversely. The theoretical method on basis of vortex model developed by the authors is applied to the Wigley hull and a container ship hull.By comparing with the measured results of captive model tests, the prediction results agree well with model tests. Therefore, this method will be useful for practical prediction of cross flow forces acting on a ship moving laterally, taking into account the forms of the ship's cross sections