The MD77RDI is a NMEA-based Rudder Angle Indicator, housed in a robust, compact aluminium enclosure. Fitted with touch panel dimmer control for background and pointer illumination. The MD77RDI provides a clear and easy to read 118 mm diameter analogue display graduated in 1 degree increments from 45 degrees PORT to 45 degrees STARBOARD. Compact and rugged, the MD77RDI offers a 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 MD77RDI from Marine Data: flexible in application, easy to installand simple to maintain.


• Clear and Easily Read Dial Display
• Rudder Angle up to 40°
• Automatic warning of lost valid rudder sensor angle data
• Automatic detection of previously lost heading data without a reset being required
• Panel or Bulkhead Mounted
• Accepts NMEA data from a Rudder Angle Transmitter
• Local and Remote Dimming Control
• Supports digital RS422 NMEA 0183


• External use on a seagoing vessel
• Used to display RSA Rudder Sensor Angle Data transmitted from marine equipment compatible with the NMEA 0183 data protocol
• Two units may be used to display dual rudder positions


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


• MD61 – Rudder Angle Transmitter
• MD94DDU – Data Distribution Unit
• The complete range of Rudder Angle Indicators from Marine Data



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; 40°sec-1 follow-up rate
Dial Illumination: Backlit white illumination; Remote Dimmer Control
Display: Rudder Angle; range 0-40°; scale graduated in 1° increments; full scale deflection 45º
Error Indication: Loss of Valid Data: Pointer assumes a vertical upward position; flashing red LED (alert condition)


IP rating: IP54
Operating temp: -15°C to +55°C
Storage temp: -25°C to +70°C
RoHS: Compliant
Magnetic: Magnetic Permeability: Category ‘A’
Compass: Safe Distance 100 cm


Conforms with:
IEC 61162-1; IEC 60945; IEC 62288; ISO 20673
IMO Res. A694 (17); IMO Res. A1021 (26)
IMO Res. MSC191 (79)
Type Approval:
Germanischer Lloyd (GL) Wheelmark
Approved for use as part of the Marine Data
RDI System