Ship maneuverability has assumed increasing importance in ship design over the last forty years as a result of major marine disasters, increasing focus on environmental protection, increasing waterway congestion, and ever larger vessels increasing the potential impacts of accidents. Agreement on performance-based international criteria for maneuverability, however, was not reached until 2002, when the International Maritime Organization (IMO) adopted a set of detailed maneuvering performance criteria and standards. Those criteria are based on empirical relationships derived primarily from ship trials data and, to a lesser extent, towing tank test data for vessels operating in deep and unrestricted water. The IMO Standards and associated performance criteria provide a valuable tool for ensuring minimum maneuverability and enhanced controllability, and for increasing operational safety in unrestricted waterways. They are of less value when applied to the highly important case of restricted waters where bottom and bank suction forces and effects of tugs and other harbor facilities play important roles in assuring safe ship controllability. It is in these restricted waters where efficient, reliable and safe operations are most important and are an absolutely necessary attribute of the logistics chain servicing today's just-in-time global maritime transportation. Existing mathematical models, which are sufficiently accurate for study of deep-water operations, generally cannot accurately predict performance under the conditions found in ports and waterways. Existing tools are thus not adequate for developing vessel designs that will meet needed, but not yet existing shallow and restricted water maneuverability performance standards. If such standards were created, compliance would probably require at a minimum full scale trials in shallow water, trials which are not possible economically. Newly available ship trials data acquisition techniques, together with major advances in modeling techniques and computers can make possible early realization of maneuvering performance standards for restricted waters and the analytical determination of ship adherence to such standards. Data measurement using dual frequency GPS positioning and other advanced navigation systems not available more than decade ago can now provide highly accurate full scale measurements of vertical in addition to horizontal position of a ship. This permits gathering data upon which to validate theories and build accurate prediction and modeling tools with which to design and check a vessel's capabilities without the necessity of performing economically feasible full scale trials in typical, critical operating conditions. In this paper, the need for further maneuvering criteria and standards is indicated. Possible means for advancing existing IMO ship maneuverability standards are discussed, together with the uncertainties associated in this process. It is believed that more accurate modeling tools can be developed with the aid of new and greatly improved shipboard instrumentation. These tools will enable further development of ship maneuverability performance standards with a methodology for assuring required capabilities through analytical means that do not require running of full-scale tests in impractical conditions. Through these means ship design, ship operational safety and maritime ship controllability standards can be developed and come to a practical implementation.
