A new radar system invented by the author and his colleagues provides a novel solution to the problem of automatic navigation along a confined waterway. The system is called “Polarimetric Radar for Accurate Navigtion” (PRAN) as it exploits polarization. The heart of the system is a retro-reflector that changes the polarization of the incident electromagnetic signal through 90°.The PRAN system uses a dual-polarized antenna (located on board the ship) and a series of reflectors located at strategic points along the shore of the waterway. It operates by transmitting a horizontally polarized signal; each reflector rotates the polarization of the incident signal by 90°; and the resulting echo is picked up by the ship’s radar on its vertically polarized antenna. The use of polarization effectively eliminates the clutter produced by natural and man-made objects located along the shores.An experimental PRAN system (using off-the-shelf components) has been set up at a site located on Hamilton Harbour. Results of experiments conducted there confirm that the system does locate the reflectors, despite the presence of clutter produced by the surrounding environment.