Display & Interface GPS Chartplotter

A GPS chartplotter is a navigation system integrated into many fish finders that combines a GPS receiver with digital mapping to display your boat's position on a detailed electronic chart. Chartplotters allow you to mark productive fishing spots as waypoints, create routes between locations, track your path on the water, and navigate safely by showing depth contours, channel markers, and hazards.

Modern combo units combine chartplotter functionality with sonar in a single device, eliminating the need for separate GPS and fish finder units. These combos typically come preloaded with mapping data — Garmin units include LakeVü maps, Lowrance includes C-MAP or Navionics, and Humminbird offers LakeMaster and CoastMaster charts. Many units also support real-time mapping features that build custom contour maps as you drive over unmapped waters.

The chartplotter becomes especially powerful when paired with sonar. You can split the screen to view your GPS position alongside live sonar, mark waypoints directly on the map when you find fish or structure, and navigate back to productive spots on future trips using saved coordinates. Premium units allow you to overlay sonar data — like structure scan images or custom depth contours — directly on the chart view for a comprehensive picture.

GPS accuracy in modern fish finders is typically within 3 to 10 feet, depending on conditions and the quality of the GPS receiver. Higher-end models use GLONASS, Galileo, and WAAS satellite augmentation in addition to GPS for improved accuracy and faster position fixes, which matters when trying to return to a precise spot on a featureless flat.