UNDERKEEL: a computer model for vertical ship movement in waves when the underkeel clearance is small

Using a simplified representation of flow beneath the hull, it has been possible to extend an earlier mathematical model for heave and pitch to describe all 6 modes of motion of a free ship in waves. The model, called UNDERKEEL, has been developed specifically for coastal applications. Its use is two-fold. It can be used directly to provide a realistic first estimate of safe underkeel allowances for vessels in navigation channels, or at berths. Its second use is in defining the hydrodynamic coefficients needed for a separate computer model called SHIPMOOR which, when fully developed, will be capable of providing a realistic first estimate of berth tenability for feasibility studies of port development.