been as manned scale models of ships, referred to as manned models, used primarily for shiphandling training. Radio-controlled scale models have also been used for shiphandling training, but only to a very limited extent. Although scale models have not been developed for training in either the coastwise or inland towing industries, where on-the-job training for shiphandling is common practice, they have been used extensively in channel design and to develop maneuvering strategies in new and unusual situations.

The level of trajectory and rates of motion (i.e., vessel response) accuracy and fidelity that are needed and delivered in the replication of ship maneuvering behavior for simulation training in both computer-based and manned-model simulation are debated within the hydrodynamic modeling, marine simulation, and marine education and training communities.

This appendix describes the modeling of vessel maneuvering used in marine simulation, the levels of accuracy present in the various modeling approaches, and where the different modeling approaches and levels of sophistication and accuracy may be most appropriate for specific training purposes. Accuracy and fidelity are also discussed from a modeling viewpoint. What constitutes a vessel's inherent maneuvering capability are described, including how these capabilities affect operations. A brief description is given of the development of modeling and simulation for marine training, with some comments on utility. Future developments are discussed, along with their potential for practical implementation. The final section is a general summary of modeling approaches and levels of sophistication available to support training objectives.

GENERAL DEVELOPMENT OF MARINE SIMULATION

Computer-Based Simulation

Ship maneuvering, a branch of naval architecture, originated from the need to design ships with maneuverability characteristics that either meet specific requirements (turning circle diameter, or tactical diameter, was an early specified requirement) or are reasonable for the mission of the ship. As the mathematical theory and the hydrodynamics of ship movement advanced, more accurate, computer-driven mathematical models were developed to represent and predict ships' trajectories.

Although analog computers were used for early models, digital computer modeling replaced analog because of the complexity of the models used for ship design. Shiphandling simulators capable of involving the human in a real-time experience were developed by combining digital computer-based models with bridge equipment, bridge mockups, and visual projection systems. As computer technology and computer-generated images advanced, so to did the shiphandling simulator (Puglisi,1987). Modern computers made it practical to create ship-bridge simulators for full-mission and multi-mission training. Computers also



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