Collection: Compass

Navigation compass: heading accuracy and system stability

The electronic compass is the essential directional reference for the consistency of your network. Its accuracy determines the quality of the autopilot's heading and the correctness of the radar overlay on your chartplotter, particularly during low-speed navigation or in strong currents.

Choosing the technology for your navigation compass

The performance of a compass varies according to its ability to filter out boat movements and magnetic disturbances.

• Fluxgate and 9-axis (Solid State) compasses: These sensors measure the Earth's magnetic field without moving parts. 9-axis models (e.g., B&G's Precision-9) incorporate accelerometers and gyroscopes to instantly compensate for heave, roll, and pitch.

• Satellite compasses (GNSS): Unlike magnetic models, they use two or three GPS antennas to calculate the true heading. The Furuno SCX20, for example, surpasses conventional 9-axis compasses by completely eliminating errors due to metallic masses or electromagnetic interference on board.

• Heading sensors vs gyroscopic compasses: Higher-end compasses offer faster data updates (10 Hz or 20 Hz), essential for ARPA radars and wind-mode pilots.

Connectivity and integration of electronic compasses

A modern compass must deliver smooth and stable information to all instruments via standardized protocols.

• NMEA 2000: Current standard allowing heading, roll, and pitch data to be shared across the entire network with minimal latency. A single compass thus feeds data to the autopilot, radar, and multifunction display.

• NMEA 0183: Still used for direct connection to certain older autopilots or specific radars requiring a high-speed data phrase (AD-10 or HS).

• Self-calibration: Recent models incorporate automatic calibration algorithms that correct magnetic deviation during the first few miles of navigation, simplifying installation.

Key features of precision compasses

Beyond simply displaying heading, high-end sensors provide crucial dynamic data for safety and performance.

• Heel and pitch compensation: Maintains heading accuracy even when the sailboat is heeled over, avoiding errors in calculating true wind.

• Heave measurement: Available on satellite compasses, this data allows sounders to correct the display of the bottom by removing the effect of swell on the signal.

• Rate of Turn: Vital information for autopilot anticipation calculations, enabling smoother tacks and trajectory corrections.

💡 Skysat Tip : Location is crucial for magnetic models. Keep your compass at least 1 meter away from any source of interference (electric motors, speakers, power cables). For steel vessels or those carrying metallic equipment, always use a satellite compass (GNSS) to ensure a true heading without deviation.