How do I choose a marine GPS chartplotter for my boat?
I want to fit a GPS chartplotter to our 31-foot cruising yacht, mainly for coastal sailing and occasional overnight passages. We currently use a tablet, and the boat has an older depth instrument and a separate AIS receiver. What screen size and connections should I prioritise?
Answer
Choose a marine GPS chartplotter you can read and operate clearly at the helm, that accepts the charts you need and connects to your existing equipment. For a typical coastal cruising boat, start with a 9-inch display; pay for a larger screen or extra networking only if your installation and navigation needs justify them.
Check the helm space
Check the mounting position first. Even an excellent plotter is little use if you must leave the helm to read it. Make a cardboard template of the unit's overall dimensions, including its bracket. Check the view seated and standing, clearance behind the panel, and access to connectors and chart-card slots.
- 7-inch: suits a small cockpit or close viewing position, but chart detail becomes cramped when sharing the screen with instruments or sonar.
- 9-inch: a practical compromise for many cruising yachts and small motorboats.
- 12-inch and above: useful for viewing from further away, radar overlays or several information panels, provided the helm has room.
List the make, model and connections of your AIS, autopilot, depth sounder, wind instruments and radar. Photograph their labels and plugs so you know what can be reused before choosing a brand.
Try the screen and controls
Compare displays in daylight, preferably wearing your usual polarised sunglasses. Look from your steering position. Check that you can distinguish depth contours, buoy symbols and shallow-water shading without leaning forward.
A touchscreen makes route planning quick. Physical buttons, a rotary controller or a compatible remote can make zooming and selecting targets easier with wet hands or on a moving boat. Try entering a waypoint, finding an AIS target's details and returning to your position. These everyday tasks matter more than a long feature list.
For an exposed cockpit, check the manufacturer's water-resistance rating and permitted mounting arrangement. An internal GNSS antenna often works well with a clear view of the sky. Metal roofs, enclosed wheelhouses and some mounting positions may require an external antenna.
A tablet is useful for planning and backup. Glare, overheating, charging connections and wet-screen operation can make it less dependable as the sole cockpit display.
Match charts and connections
Check chart coverage for your cruising area, including likely holiday destinations. A worldwide basemap is not detailed navigation charting. Confirm which regional charts are included, how updates work and what remains available when a subscription expires.
Compare Garmin GPSMAP, Raymarine Axiom, B&G and Simrad ranges, but check compatibility by model and generation. Match the exact unit to the exact chart product. A familiar chart brand does not guarantee that an existing card will work.