The Sonic Heading Gyro is the heart of the system. It is a light weight and maintenance free electronic Gyro Compass, manufactured by TECNAUTIC since 1992. It sends the ships heading to the cockpit displays and to the Autopilot with a precision of 0.1degrees. In addition, it transmits rate of turn with a precision of 0.05 degrees per second. Without delay and with zero hysteresis (no backlash). Rough seas and rapid motion will not cause an error of the Heading Gyro. The Sonic Heading Gyro is attached either to a display unit or to an electronic steering wheel. The gyro is slewed to magnetic north by a flux gate or by a GPS receiver. Together with a GPS, the gyro forms a GPS-Gyro-Compass on a moving boat. This feature is especially useful on large vessels, where a flux gate cannot work reliably.