Abstract: A navigation system provides a shore-based continuous visual signal to a ship navigating a channel or approaching a jetty. This indicates to the ship the optimum velocity program that it should be following, which is normally a gradual reduction of speed as the ship approaches its destination. The signal is a moire fringe display (33, 34, 35) from a rotating projector (21) which tracks the intended path under the control of a computer program. From the ship, the fringes are static if it is at the correct speed, but they move in one or other direction to indicate too fast or too slow. If the ship strays beyond an acceptable sector, the projector and program can be stepped on or back to maintain an appropriate signal visible to the ship.