4.1 Initial Validation Efforts

　

 Initial simulation tests to compare the ship model results have been performed to start defining the validation methodologies. Initial simulations of the mini-zig-zag maneuver of the New Amity in the Lower Bay using the measured rudder and RPM positions were unsuccessful. After several attempts to model the currents in a simplified uniform field, attempts to model this maneuver were abandoned. This portion of Galveston Bay experiences relatively high currents and, therefore, current patterns need to be accurately modeled for this simulation. Such model results were not available for this paper, therefore, this effort was abandoned.

　

　

　

 The next attempt for simulation comparisons was to model approaching, making, and recovering from the turn at Red Fish Island (Channel Markers 51-52). At this location, the currents tend to be reduced significantly and are generally aligned with the navigation channel. However, the navigation channel widening and deepening 530ft x 45 ft (161.6m×13.7m) transitions suddenly at this location to the old channel dimensions 400 ft × 40 ft (122 m x 12.2 m), see Figure 7. Survey lines and modeled cross-sections are also shown in this figure. Again, the simulations using the measured controls did not reproduce the measured ship track and behavior.

　

　

 As a result of these initial test, it was decided to concentrate the initial tests on the simplest case possible. This would allow the determination of whether the simulation model (consisting of ship, channel, currents, shallow water effects, and bank effects sub-models) can reproduce the confined channel effects on the control with minimual complications.