Optimising ferry routes

In open waters, the skippers of passenger ferries have some leeway to plot a course that balances fuel efficiency, safety, and passenger comfort whilst still maintaining a tight schedule. This paper describes the seeking of an optimal ferry course for a 400t vehicular and passenger ferry. Numerical dynamic optimal control studies based on the vessel's actual operating data, bathymetry and tidal streams showed that depth under keel was important in periods of slack water which fortuitously in this location happens to be adequately approximated by a simple straight line. During times of strong tidal streams, the optimal trajectory improved travel time by about 3.5% compared to the simple hooked curve course.