MD71TMC: Transmitting Magnetic Compass (TMC) System

REF: MNE-0025

SKU: MNE-0025


The MD71TMC is a Transmitting Magnetic Compass (TMC) System that uses the latest technology to accurately process and convert the ship’s magnetic compass heading to NMEA 0183 heading data. With unparalleled accuracy to one or more Heading Repeaters (Compass Repeaters) at any convenient location on a vessel.
Instead of using inflexible and bulky optical apparatus (reflectors, periscopes, etc.) to view the magnetic compass, electronic remote displays may be used in the form of a Compass Repeater.
TMC systems from Marine Data are simple and intuitive to use. Also, with quick and easy installation and on-board calibration.


  • Provides Digital Heading Data from a Ship’s Magnetic Compass
  • Unparalleled Accuracy; Intuitive Operator Controls
  • Correction of Magnetic Deviation and Variation
  • Automatic Sensor-to-Compass Calibration
  • Rugged, IP65 rated Magnetic Sensors
  • Industry Proven Design
  • Bright OLED display provides high contrast and wide viewing angles


  • Provides a digital NMEA heading output to drive a Heading Repeater (or other devices). Situated at a convenient location.
  • An elegant alternative to using an optical reflector in a ship’s magnetic compass installation.

ACCESSORIES – For Accessories quotes please email

  • MD54 – Compass Sensor Adhesive Mount
  • MD58 – Compass Sensor Bracket Mount
  • MD71TB – Trunnion Bracket Kit for Display & Control Head
  • MD96JB/8 – Junction Box to supply power and also, act as a breakout box for 2x NMEA 0813 data channels
  • MD94DDU – Data Distribution Unit to supply power and also for feeding several Heading Repeaters


MD97TMC – Standard Transmitting Magnetic Compass System
MD71EMC – Electro-magnetic Compass System

Increasingly, Maritime Authorities areaccepting the use of Transmitting Heading

Device (THD) Systems onboard vessels.

Marine Data offers two types of THD system:

  • A system which senses the angular position of a ship’s magnetic compass card; known as a Transmitting Magnetic Compass System (TMC)
  • A system which directly senses the Earth’s magnetic field; known as an Electro-Magnetic Compass System (EMC)

By Marine Data

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Item Measurements
MD71THD: H 96; W 96; D 35 (mm); 0.50 kg MD97CSP: L 146; W 64; D 41 (mm); 0.35 kg MD52A/B: H 18; 69 (mm); 0.12 kg
Data Sheet

Please note that due to the complex nature of shipping for certain products it will be more cost effective to contact AMI directly using the address or the telephone number +44 (0) 2380 480450, for a bespoke quotation.

Our team are able to create bespoke quotations for you for all of your needs and delivery requirements.

We are able to ship to all parts of the world. Transit times vary and are usually between 2 and 5 days depending on the destination.

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