What is VDR OR Voyage data recorder ? What data items must be recorded by the VDR as per IMO Resolution ? |

What is VDR OR Voyage data recorder ? What data items must be recorded by the VDR as per IMO Resolution ?

vdr system
Written by Amit Sharma

Voyage data recorder, or VDR, sometimes also called Black box of the ship is a data recording system designed for all vessels required to comply with the IMO‘s International Convention SOLAS Requirements (IMO Res.A.861(20)) in order to collect data from various sensors on board the vessel. It then digitizes, compresses and stores this information in an externally mounted protective storage unit. The protective storage unit is a tamper-proof unit designed to withstand the extreme shock, impact, pressure and heat, which could be associated with a marine incident (fire, explosion, collision, sinking, etc.).

The protective storage unit may be in a retrievable fixed unit or free float unit (or combined with EPIRB) when the ship sinks in a marine accident The last 12 hours of stored data in the protected unit can be recovered and replayed by the authorities or ship owners for incident investigation. Besides the protective storage unit, the VDR system may consist of a recording control unit and a data acquisition unit, which are connected to various equipment and sensors on board a ship.

Although the primary purpose of the VDR is for accident investigation after the fact, there can be other uses of recorded data for preventive maintenance, performance efficiency monitoring, heavy weather damage analysis, accident avoidance and training purposes to improve safety and reduce running costs.

Data types

Date and time:

Referenced to UTC with an indication of the source. The source could be the GPS .

Ship’s position:

In latitude and longitude with the datum used. The source could be the GPS .


Through water or speed over ground with indication of which it is. The source could be the speed log.


As indicated by the ship’s compass. The source could be the gyro compass.

Bridge audio:

As picked up by one or more microphones positioned on the bridge so that conversation at or near the conning stations, radar displays, chart tables, etc., is adequately recorded. As far as practicable, the positioning of microphones should also capture intercom, public address systems and audible alarms on the bridge

VHF communications

Relating to ship operations should be recorded

Radar data:

Electronic signal information from within one of the ship’s radar installations with recording of all the information which was actually being presented on the master display of that radar at the time of recording

AIS data:

If it is impossible to obtain radar data by using a commercially available interface then AIS target data should be recorded as a source of information regarding other ships. If radar data is recorded, AIS information may be recorded additionally as a beneficial secondary source of information on both other and own ship. AIS data is not mandatory, but an option when it is impossible to obtain radar data by means of a commercially available interface.

Additional data:

Items listed by IMO with the requirements set out in resolution A.861(20) should be recorded when the data is available in accordance with the international digital interface standard NMEA0183 using approved sentence formatters. The additional data listed by IMO with the requirements in resolution A.861(20) are:

  •  Echo sounder
  • Main alarms
  • Rudder order and response
  • Engine order and response
  • Hull openings status
  • Watertight and fire door status
  • Accelerations and hull stresses
  • Wind speed and direction
  • The additional data (any or all) shall only have to be recorded if the data are available on the bridge and the data    signals are available in NMEA0183 format.

Simplified Voyage Data Recorder (S-VDR), as defined by the requirements of IMO Performance Standard MSC.163(78), is a lower cost simplified version VDR for small ships with only basic ship’s data recorded. It is not required to store the same level of detailed data as a standard VDR, but nonetheless should maintain a store, in a secure and retrievable form, of information concerning the position, movement, physical status, command and control of a vessel over the period leading up to and following an incident.

Hence, the principle difference between VDR and S-VDR lays in the requirements for recording of additional data

Date and Time X X
Ship’s Position X X
Speed X X
Heading X X
Bridge Audio X X
Communications Audio X X
Radar Data X X
AIS – (Radar alternative)   When no radar signal is available
Acceleration and Hull Stresses (if fitted) X Only when they are available on the bridge via an IEC 61162 interface
Echo Sounder X
Engine Order and Response X
Hull Openings (Doors) Status X
Main Alarms (IMO Mandatory Bridge Alarms) X
Rudder Order and Response X
Watertight and Fire Doors Status X
Wind Speed and Direction




About the author

Amit Sharma

Graduated from M.E.R.I. Mumbai (Mumbai University), After a brief sailing founded this website with the idea to bring the maritime education online which must be free and available for all at all times and to find basic solutions that are of extreme importance to a seafarer by our innovative ideas.