The Marine Data MD77HRB is a weatherproof, bracket-mounted NMEA dial compass heading repeater display manufactured in the United Kingdom by Marine Data Systems. Derived from the standard MD77HR panel repeater, the “B” variant is housed within a fully enclosed, IP66-rated weatherproof enclosure featuring an adjustable trunnion/bulkhead mounting bracket for exposed bridge wings, steering stations, and open wheelhouses.

The display features a high-contrast 150mm (approx. 6-inch) dual-scale dial card layout (360° outer scale paired with an expanded inner scale) providing 0.1° heading resolution. Built into a powder-coated marine-grade aluminum housing, the MD77HRB decodes serial NMEA 0183 heading sentences ($HDT, $HDG, $HDM, $THS) from gyrocompasses, satellite compasses, and magnetic heading sensors. Variable red LED dial illumination ensures glare-free night-watch operation on the bridge.

Key Features:
• IP66 Weatherproof Bracket Mount: Heavy-duty enclosed housing with adjustable mounting bracket designed for exposed wheelhouses, chart tables, and bridge wings.
• 150mm High-Visibility Dial Display: Clear dual-concentric dial layout delivering precise heading readings with 0.1° digital resolution.
• Universal NMEA 0183 Interfacing: Decodes standard NMEA 0183 serial heading data ($HDT, $HDG, $HDM, $THS) with automatic baud rate sensing.
• Variable Red Night Illumination: Dimmable red LED dial backlighting controlled locally via rotary knob or remotely via NMEA commands.
• Marine Class Approved Reliability: Rugged aluminum alloy chassis engineered to satisfy IEC 60945 environmental, vibration, and EMC standards.