Hydrodynamic Forces Caused by a Ship in Confined Waters

The use of slender-body theory to predict the hydrodynamic disturbance caused by a ship maneuvering in confined waters is reviewed. Various configurations are described including: (1)Shallow water; (2)canals; (3)dredged channels; and (4)ship-to-ship interactions. Particular attention is paid to the determination of the sinkage, trim, lateral force and yaw moment. Examples are also given to the pressure distribution over the bottom and on the canal walls. Several general conclusions are drawn. The important speed parameter is the Froude number based on depth. Near the critical value of Fh=1.0, the simple linear analysis used is no longer valid. Secondly, as the waterway becomes more restrictive (i.e., as the water depth or width, or both, decreases), the forces acting on the vessel increase dramatically. This results in an increase in the squat and greater difficulty in controlling the ship.