The Houston/Galveston Navigation Channels are located along the Gulf of Mexico Coast in eastern Texas. These channels include the Entrance Channel, the Bar Channels (Bolivar Roads Area), Galveston Channel, the Texas City Channel, the Gulf Intercoastal Waterway (GIWW), and the Houston Ship Channel (HSC), which branches off the Bolivar Roads Channel, traverses Galveston Bay, and ends in Houston. The HSC consists of approximately 65 miles of improved deep-draft channels. The present channel is 400 ft wide and 40 ft deep at mean low tide for most of the channel distance. The project design calls for the channel to be improved in two phases. The Phase I channel is to be 530 ft wide and 45 ft deep, and the Phase II channel is to be 600 ft wide and 50 ft deep. A navigation study was conducted for the Houston/Galveston Navigation Channels, including a real-time ship simulation of the project area, to determine a cost-effective channel design for safe navigation. The Texas City Channel and the section of the HSC past Boggy Bayou are not included in the improvement project. The HSC is designed for two-way deep-draft traffic. The capability of large loaded vessels to meet and pass is the primary factor in determining safe channel width. In the highly restricted channel, both bank and ship interaction effects are significant factors in conducting bow-on meeting and passing maneuvers. Prototype data and data from a physical model were used to provide guidance in simulating this maneuver. Other considerations in channel design include several sharp turns, strong currents in certain areas, shallow-draft traffic, location of docks and moored vessels, turning basin operations, overtaking area, and channel marking. Hydrodynamic modeling of the bay was a key element of the study and provided currents for the navigation design.