These splashproof cards take the mystery out of using radar on a small boat for navigation and collision avoidance. A radar screen in the cockpit is the most useful tool for navigation. It can show you the land and approaching boats in daylight, in darkness and in fog. And, combined with GPS, it can show you your position and destination relative to the land as a 'birds eye view'. Pat Manley concentrates on using the controls to get the best picture, then explains how to understand the display and gives plenty of examples of radar plots.