VDR (Voyage Data Recorder)

Understanding Voyage Data Recorders or VDRs

Often considered similar to airplane black boxes, a Voyage Data Recorder is a system fitted onboard ships that record the various data on a ship which can be used for reconstruction of the voyage details and vessel information during an accident investigation.

The IMO defines the Voyage Data Recorder as a system, including any items required to interface with the sources of input signals, their processing and encoding, the final recording medium, the playback equipment, the power supply and dedicated reserve power source.

VDR information is stored in a secure and retrievable form, capturing the movement, status, position and command and control of a ship. This information can be used during any subsequent safety investigation to identify the cause of the incident. As well as incident investigation, VDRs are increasingly used for preventive maintenance, performance efficiency monitoring, damage analysis, accident avoidance and training purposes to reduce running costs, improve safety and provide greater onshore visibility of how the vessel is being operated.

Netwave NW6000 VDR configuration

VDR recording Requirements

A voyage data recorder is a system installed on a ship to continuously record key information related to the operation of a vessel. It contains a voice recording system for a period of at least last 12 hours, for VDRs installed post-July 2014, the period of the integrated details recorded is 48 hours as per the MSC Resolution 333.90. This compressed and digitised recording can be recovered and made use of for incident investigation. The VDR recording media is designed to be capable of withstanding collisions, water pressure and extreme heat, ensuring relevant data is preserved.

The VDR has a Data Collection Unit (DCU) fitted on the bridge that pulls in data from all the integrated sources. The Data Recording Unit (DRU) stores all of the data that is recorded via the unit within the wheelhouse, including microphones to record bridge audio. The DCU contains the Data Processor Unit, interface modules and backup batteries. It collects data from sensors as required by the IMO and IEC standards. The batteries supply power to the DCU to record bridge audio for 2 h in case of a main ship’s power failure. The flash memory in the DRU stores the data coming from the DCU. The data can be retrieved by using playback software for investigation after an incident. The DRU components are embodied in the protective capsule, designed for survival and recovery of the recorded data after an incident.

VDR data that is collected or pulled in from all the integrated sources is stored in the storage capsule and holds information for the 12 hours (or 48 hours) preceeding it and is continuously refreshed as the voyage progresses.

There is also a float-free arrangement linked to an EPIRB allows a data source to be released from the vessel in the case the vessel is lost.

  • Date and time (SVDR)
  • Ship’s position (SVDR)
  • Speed and heading (SVDR)
  • Bridge audio (SVDR)
  • Communication audio (radio) (SVDR)
  • Radar data (SVDR)
  • ECDIS data (SVDR)
  • Echo sounder
  • Main alarms
  • Rudder order and response
  • Hull opening (doors) status
  • Watertight and fire door status
  • Speed and acceleration
  • Hull stresses
  • Wind speed and direction


The SVDR is a simplified VDR, that records information that is only absolutely necessary and does not record information as extensive as the VDR. It is more cost effective and more in usage on board merchant vessels.

Legal Requirements for VDR

The VDR comes under the purview of the SOLAS Chapter V, Regulation 20 as well as Annex 10. The details of it are as follows:

Passenger ships constructed on or after 1 July 2002 VDR
Ro-ro passenger ships constructed before 1 July 2002 VDR
Passenger ships other than ro-ro constructed before 1 July 2002 VDR
Ships other than passenger ships of 3000 GT and upwards constructed on or after 1 July 2002 VDR
Cargo ships of 20000 gt. and upwards constructed before 1 July 2002* VDR or S-VDR
Cargo ships of 3000 GT and up to 20000 GT constructed before 1 July 2002 * VDR or S-VDR

* Cargo ships built before 1 July 2002 may be exempted from requirements to carry VDR /S-VDR when they are to be taken permanently out of service within 2 years of the relevant implementation date.

General Operational Requirements

The VDR should continuously maintain sequential records of pre-selected data items relating to the status and output of the ship’s equipment and command and control of the ship. To permit subsequent analysis of factors surrounding an incident, the method of recording should ensure that the various data items can be correlated in date and time during playback on suitable equipment.

The system should include functions to perform a performance test at any time, e.g. APT or following repair or maintenance work to the VDR or any signal source providing data to the VDR. This test may be conducted using the playback equipment and should ensure that all the required data items are being correctly recorded.


Regulation 18.8 of SOLAS Chapter V states the requirements for maintenance. A certificate stating that the results of Annual performance tests (APTs) are required to be retained onboard. Only qualified personnel should review and maintain VDR systems and carry out APTs. The battery should be replaced every four years, the backup battery must be replaced with new one by a qualified service engineer.

Underwater Acoustic Beacon

This beacon can be seen in the capsule on the monkey island and is fitted as a homing device to locate the capsule after a mishap. It is attached to a bracket on the capsule. Triggered by immersion in water, they give out pulses in the ultrasonic that can be detected by airborne or shipborne units.

It is important to understand that the VDR/SVDR is not just a way to record data for use later on during accident investigation, but it gives the trainers as well as the trainees to understand real life situations at sea and the ways they could be combatted to further prevent any future mishaps, enabling better practical approach towards ship operations at sea.