The Marine Data MD73HR is a specialized electromechanical tape-style NMEA compass heading repeater manufactured in the United Kingdom by Marine Data Systems. Designed for overhead bridge mounting, main helm consoles, and wheelhouse steering positions, the MD73HR provides visual heading indication using a continuous moving tape compass display alongside a digital numeric readout.

The display features a wide horizontal tape card scale (showing a continuous 35° section of the compass card) that moves smoothly behind a fixed lubber line, simulating traditional submarine tape repeaters and high-visibility steering indicators. The MD73HR processes standard NMEA 0183 heading sentences ($HDT, $HDG, $HDM, $THS) from shipboard gyrocompasses, satellite compasses, and magnetic sensors. Variable red LED backlighting guarantees glare-free operations during night watches without impairing night-adapted vision.

Key Features:
• Continuous Moving Tape Scale: High-contrast moving tape display provides smooth, intuitive visual tracking of vessel heading changes.
• Combined Digital & Analog Layout: Features an electromechanical tape scale paired with a digital numeric readout for precision and quick readability.
• Universal NMEA 0183 Interfacing: Decodes serial NMEA 0183 heading sentences ($HDT, $HDG, $HDM, $THS) with auto-sensing baud rate selection.
• Variable Red Night Illumination: Dimmable red LED backlighting controlled locally via front panel knobs or remotely via NMEA serial commands.
• Rugged Marine Build: Enclosed in a powder-coated marine-grade aluminum alloy housing built to satisfy IEC 60945 standards.