Use a marine GPS by configuring the unit, setting the destination and following the onscreen or voice-directed instructions for navigation. Combination fishfinder and marine units may also allow users to choose GPS-directed courses towards the nearest sensed concentration of fish, and more advanced units may have additional setup requirements.
Turn on the unit, and wait for the GPS to load. Configure the marine GPS by choosing the hemisphere in which the boat currently rests. The unit connects with GPS satellites to determine the current location of the vessel. Use the chartplotter function of the marine GPS to set a destination. This may be the name of a city, longitudinal coordinates, a buoy or another nautical point of interest. Units with fishfinders may also offer options for courses charted to common locations of specific fish species.
Launch the coursefinder path from the GPS, and follow the instructions provided by the system to the destination. Users who wish to sail without a set destination may still select a location as a home point on many GPS systems and choose to return to a homeward course at the press of a button. Many systems offer voice-aided navigation that allows captains or navigators to pilot the vessel without needing to watch the screen for updates. Some may even let users select multiple alternate routes in case of crowded fishing, shipping channels or inclement weather.