Satellite Speed Log

A satellite speed log is a marine instrument that measures a vessel’s speed over ground (SOG) by using signals from Global Navigation Satellite Systems (GNSS) such as GPS. Unlike traditional Doppler or electromagnetic logs that measure speed through water, a satellite speed log calculates speed based on the vessel’s actual position changes over time, providing highly accurate readings regardless of currents or water conditions. These systems typically include a GNSS receiver and a display unit, and they often integrate with other navigation equipment like ECDIS, radar, and AIS for comprehensive data sharing. Satellite speed logs are valued for their precision, reliability, and minimal maintenance requirements since they have no moving parts or hull penetrations. They are widely used on modern ships to comply with IMO performance standards and are particularly useful for fuel optimization, voyage planning, and ensuring compliance with speed-related regulations.