The MD77HR is a NMEA-based Compact Heading Repeater. Digital heading data (ship’s heading) may be conveniently displayed and monitored at any location on a vessel. When multiple heading sources are available in the heading data (e.g. True and Magnetic) the MD77HR allows the user to select the heading source and indicates which heading source is in current use. Compact and rugged, the MD77HR offers a heading repeater solution for locations where the available space is limited and may be either bulkhead or panel mounted. Finished in jet black to complement other marine navigation equipment.

The MD77HR from Marine Data: flexible in application, easy to install and simple to maintain.


• Traditional Marine Compass Card Display
• Main and Emergency power supplies; with monitoring of both
• Automatic Baud Rate Detection
• Automatic warning of loss of valid heading data
• Automatic detection of a previously lost heading data type without requiring a reset
• Prioritisation of heading type
• Local and Remote Dimming Control
• Rugged, Marinised Aluminium Construction


• The MD77HR displays True or Magnetic Heading Data transmitted from marine equipment compatible with NMEA 0183 (IEC 61162- 1) (Gyro compass, TMC, EMC, GPS Compass etc.)


• Panel Mounting Kit (Supplied)
• Bulkhead Bracket Mounting Kit
• Remote Dimmer Control (0-24 V dc)


• The complete range of Marine Data Heading Repeaters
• Transmitting Heading Device (THD) Systems (TMC and EMC)



Weight: 1.25 kg (on bracket)
H 166 mm; W 200 mm; D 87 mm (on bracket)
Fascia 144 x 144 x 6 mm deep; dial Ø 118 mm
140 mm square panel cut out required
Mounting: Panel or optional Bulkhead mounted
Connections: 1 x data cable to 15-pin D-sub plug
Construction: Aluminium alloy enclosure
Finish: RAL9005 Jet Black; fine texture


Power Supply: 24 V to 28 V dc; 10 W
Data input: Digital NMEA 0183 (IEC61162-1); 4800 baud
Data sentence: RSA ($–RSA,x,x,A,x,x,A*hh)
Cable: Supplied with 2.5 m multi-core data cable


Performance: ± 0.5° accuracy
Follow Up Rate: >20° per second
Dial Illumination: LED array with local and remote dimming control. Red tint
Dial Resolution: Scale marked at 1°, 5°, 10° & 45°
Display: Rotating compass card dial display
Alarm: Power supply failure: Audible and visible indications
Error Indication: Dial oscillates ±35° about the last known good heading. Dial illumination flashes
Heading Type: LED indicator for heading source type: Gyro Compass / Magnetic Compass
MTBF: 30,000 hours


IP Rating: IP54
Operating Temp: -15°C to +55°C
RoHS: Compliant
Compass: Safe Distance 100 cm


Conforms with: IEC 60945; IEC 62288; IEC 61162-1 ISO 8728; IMO Resolution A1021 (26)
Type Approval: Germanischer Lloyd (GL)