CRITICAL NEEDS FOR SHIP MANEUVERABILITY: LESSONS FROM THE HOUSTON SHIP CHANNEL FULL-SCALE MANEUVERING TRIALS

The Standards for Ship Maneuverability approved by the International Maritime Organization (IMO) in 2002 represent a significant step forward in ensuring adequate maneuverability of ships. The Standards provide numerical criteria for assessing the adequacy of maneuverability in deep, unrestricted water at sea speed. Explanatory notes to the Standards provide useful guidelines to the assessment and validation process that help with various issues, such as adjusting full-scale trial results for environmental and loading conditions. Major issues exist, however. In question is the ability of the standards to ensure adequate maneuverability in shallow, restricted, and congested waterways under vessel meeting and passing conditions with the interaction effects, bank suction, and other situations that are encountered in normal port, harbor, and waterway operations. Historically, even in shallow water that is unrestricted, only a couple of ship trials have ever been conducted due to the great cost to prepare for such tests. The lack of accurate full-scale data has seriously limited the accuracy capable of being built into mathematical prediction models. Recently, however, revolutionary positioning technology has enabled collecting highly accurate track and vertical position data on ships operating in shallow and restricted water, with and without interacting ship traffic. Accurate mathematical modeling of ship operations in complex harbors and waterways has become a critical need, and now the possibility of advancing the science finally exists. With accurate full-scale trials data and improved prediction techniques, such as computational fluid dynamics, such ability now seems attainable.