The MD77HRB from MARINE DATA is a NMEA-based Compact Heading Repeater with a clear and easy to read analogue dial display of heading data.


The MD77HRB from MARINE DATA is a NMEA-based Compact Heading Repeater with a clear and easy to read analogue dial display of heading data. The 118 mm diameter dial is graduated in 1 degree increments. The MD77HRB is housed in a robust, compact aluminium enclosure fitted with a rotary encoder for controlling the level of background illumination. Finished in jet black to complement other marine navigation equipment, it is ideal for any vessel.

When multiple heading sources are available in the heading data (e.g. True and Magnetic) the MD77HRB automatically prioritises and indicates which heading source is in current use. The encoder has a pushbutton facility for an internal self-test.

Compact and rugged, the MD77HRB offers a heading repeater solution for digital heading data (ship’s heading) to be displayed and monitored at any convenient location on a vessel. Suitable for locations where the available space is limited and may be either bulkhead or panel mounted.

The MD77HRB from MARINE DATA: Flexible in application, easy to install and simple to maintain.


  • Automatic selection and prioritisation of NMEA heading data type
  • Prioritisation of heading type: HDT (true), HDG (magnetic + variation), HDM (magnetic)
  • Automatic warning of loss of valid heading data and automatic detection of a previously lost heading data type without requiring a reset
  • Rotary dimming control with remote connection; Supply under-voltage lock-out


  • The MD77HRB displays True or Magnetic Heading Data transmitted from marine equipment compatible with NMEA 0183 (IEC 61162-1) (Gyro compass, TMC, EMC, GPS Compass etc.)


  • Weight: 1.25 kg (on bracket)
  • Dimensions: H 166 mm; W 200 mm; D 101 mm; Fascia 144 x 144 mm; dial Ø 118 mm
  • Mounting: Bulkhead or Panel mounted
  • Connections: 1x data cable to 15-pin D-sub plug
  • Construction: Aluminium alloy enclosure
  • Finish: RAL9005 Jet Black; fine texture paint


  • Power Supply: 24 V dc (18-32 V dc) 4 W nominal
  • Data Input: Digital RS422; NMEA 0183 protocol; 4800 / 9600 / 19200 / 38000 Baud (auto-sensing)
  • Data Sentences: THS, HDT, HDG and HDM; detected on start‐up in descending order of priority
  • Cable: Supplied with 2.5 m multi-core data cable


  • Performance: Better than ± 0.5° accuracy
  • Follow-Up Rate: >= 20° per second
  • Display: Rotating compass card dial display
  • Dial Resolution: Scale marked at 1°, 5°, 10° & 45°
  • Dial Illumination: LED array with local and remote dimming control, red tint
  • 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: Pending


  • Supplied: Panel Mounting Kit
  • Supplied: Data Cable SS20001
  • Option: Custom Paint Finish


  • Bulkhead Mounting Kit – MD77TB
  • Panel Mount Remote Dimmer – SS37120

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