Quite amount of efforts have been made to rescue the grounded ships in the shallow water of ports or coastal lines in the recent decade due to the increasing of the vessel principal dimensions and vessel traffics. The major grounding reason is the restriction of water depth of the port or coastal water area during the ship maneuvering operation. The under keel clearance of a maneuvering ship in the port or coastal water zone should be such that the ship can move safely. Also as many pilots experienced that maneuvering controllability such as the rudder and propeller functions in shallow water is different from the ones in deep water. The shallower the water depth, the higher the inflow velocity at the rudder which will increasing the rudder normal force or create the partial vacuum in the region of the propeller. Therefore, the vessel maneuverability may become erratic or out of control. In current study, the factors which could be possible to affect the ship operating behavior in shallow water have all been included such as the under keel clearance, the squat, the sinkage and trim, the wave making resistance, the rudder normal force and propeller efficiency, the hydrodynamic hull lateral forces and yaw moments. The certain predicted results have been verified by the sea trial measurements. The reasonable agreements have been found for squat and turning circles. Therefore, the suggestion for the navigation simulator is that all the simulations should cover the water depth effects.
Ship usually has a couple of motion modes before it gets grounded such as the vertical motion mode in shallow water zone to touch down the ocean floor and suffer grounded, or, the plane motion mode to climb on the sea bed shelf and get grounded.
