The Global Positioning System (GPS) is the first worldwide 24 hour, all-weather navigation system. This book aims to help yacht owners get the best from their sets and make full use of the facilities available, whether simply position fixing and course setting or interfacing with radar, Loran, autopilots, logs, chartplotters, video sounders and fishfinders. The author explains how to use and interpret the data received, test it for accuracy and correct it when necessary. He advises what to look for when buying a set, how to achieve optimum accuracy and unravels the jargon associated with instruction manuals.