VDR and S-VDR- Requirements, Working, Benefits, Differences

What is VDR?

A VDR or Voyage Data Recorder is an instrument installed on a ship to continuously record critical information related to the operation of a vessel. It consists of a recording system for a period of at least the last 12 hours which is continuously overwritten by the latest data. This recording is recovered and made use of for various purposes, especially for investigation in the events of accidents.

Just like the black boxes carried on aircraft, VDRs enable accident investigators to review procedures and instructions in the moments before an incident and help to identify the cause of an accident.

Carriage Requirements

​Passenger ships and ships other than passenger ships of 3000 GRT and above, constructed on or after 1 July 2002 must carry voyage data recorders (VDRs) to assist in accident investigations, under regulations adopted in 2000, which entered into force on 1 July 2002. 

Under Regulation 20 of SOLAS Chp V on Voyage data recorders (VDR), the following ships are required to carry VDRs:

  • Passenger ships constructed on or after 1 July 2002;
  • Ro-Ro passenger ships constructed before 1 July 2002 not later than the first survey on or after 1 July 2002;
  • Passenger ships other than Ro-Ro passenger ships constructed before 1 July 2002 not later than 1 January 2004; and
  • Ships, other than passenger ships, of 3,000 GRT and upwards constructed on or after 1 July 2002.

VDRs are required to meet performance standards “not inferior to those adopted by the Organization”.

Performance standards for VDRs were adopted in 1997 and give details on data to be recorded and VDR specifications. They state that the VDR should continuously maintain sequential records of preselected data items relating to the status and output of the ship’s equipment and command and control of the ship. The VDR should be installed in a protective capsule that is brightly colored and fitted with an appropriate device to aid location. It should be entirely automatic in normal operation.

Administrations may exempt ships, other than Ro-Ro passenger ships, constructed before 1 July 2002, from being fitted with a VDR where it can be demonstrated that interfacing a VDR with the existing equipment on the ship is unreasonable and impracticable.

Regulation18 of SOLAS Chapter V on Approval, surveys and performance standards of navigational systems and equipment and voyage data recorder state that:

“The voyage data recorder (VDR) system, including all sensors, shall be subjected to an annual performance test. The test shall be conducted by an approved testing or servicing facility to verify the accuracy, duration, and recoverability of the recorded data. In addition, tests and inspections shall be conducted to determine the serviceability of all protective enclosures and devices fitted to aid location. A copy of the certificate of compliance issued by the testing facility, stating the date of compliance and the applicable performance standards, shall be retained on board the ship.”

Purpose of VDR

  • The main purpose of media is to record and store the data that is shift critical parameters;
  • For navigators, it is a lesson learning tool and does improve improvement into the procedure in the future;
  • A VDR can be used to identify the major cause of actors accident which for the make a major contribution to maritime safety:
    • promotion of the safe practice
    • for investigation and inquiry of accidents;
    • to respond to assessment and study;
    • for training aid and support;
    • for a reduction in insurance costs.

Working of VDR

  • There are various sensors placed on the bridge of the ship and on prominent locations from which the required data is continuously collected. The VDR has to be very flexible in order to be interfaced with the existing equipment and sensors for recording relevant data.
  • The unit should be entirely automatic in normal operation.
    Means are provided whereby recorded data may be saved by an appropriate method following an incident, with minimal interruption to the recording process.
  • All this data or information are then waiting at a storage unit where the whole input is recorded and saved for at least 12 hours.
  • There are also ‘Record” buttons provided in the pressure units that after pushing the button the recorder will start recording a new set of information from that period of time, say during the start of the incident like pollution or grounding.
  • The data collected by VDR is digitalized, compressed, and is stored in a protective storage unit which is mounted in a safe place. This tamper-proof storage unit can be a retrievable fixed or floating unit connected with EPIRB for early location in the event of an accident.

Storage Units:

  • Primary Storage Unit:

    • kept in the Bridge,

    • this is a fixed-type unit

    • has a maximum storage capacity of 30 days or 720 hours;

    • usually used in coastal ships.

  • Secondary Storage:

    • also of a fixed-type;

    • kept inside the Bridge;

    • has 12-hour storage;
    • has a display on the VDR

  • Float-free Storage System

    • has a storage of 48 hours;

    • has a fixed HRU

    • contains a portable capsule.

    • can float free with one EPIRB for up to SIX months at least;

    • this is also called as Black Box;

    • should be made of highly visible colors and use retro-reflective material

Data to be recorded by VDR

The VDRs installed before 1st July 2014 must record the following data:

  • Date & time every 1 second, preferably external to ship (e.g.GNSS)
  • The ship’s position in lat and long,
  • the datum used
  • Speed Over Ground or Speed through Water, Recorded every 1 second to 0.1k resolution
  • Ship’s Heading from Ship’s compass, recorded at intervals of 1s to a resolution of 0.1 deg.
  • Bridge Audio from one or more bridge microphones. Recorded in real-time, both internal and external (150-6000 Hz). This mic test beeps every 12 hrs and this is recorded
  • Communication Audio, from two VHFs; recorded for both transmitted and received audio signals. Audio is compressed and labeled VHF-1 and VHF-2
  • RADAR/ ARPA Display, every 15 secs, from master RADAR Display, including Range Rings, EBLs, VRMs, Radar Maps, parts of SENC, and other essential navigational indications
  • ECDIS Display, in use at the time as the primary means of navigation; 
  • Water Depth from Echo Sounder recorded to a resolution of 0.1 meter
  • Main alarms such as the Main Engine alarm, Steering failure alarm, Fire detection alarm; Bridge VDR Microphones to be recorded with time-stamps. All IMO Mandatory Alarms as well as other mandatory alarms are stored individually
  • Rudder Order and response from/to steering gear and autopilot
  • Engine order & response from telegraphs, controls, and thrusters;
  • Bow thruster order and response; from Bow and/or Stern thrusters. Can be recorded for their orders and responses
  • Hull opening status; from all mandatory status information displayed on the Bridge. to be recorded every 1 sec and stored with time-stamps
  • Wind speed and direction; from Anemometer if fitted, should be stored individually with time-stamps; 
  • AIS target data (if Radar picture is not recorded) should be recorded as a source of information regarding other ships

VDR installed after 1st July 2014 must record, in addition to, or alternately, following data:

  • Bridge Audio should be recorded through the use of at least two channels of audio recording. Microphones positioned outside on bridge wings should be recorded on at least one additional separate channel.
  • VHF Communications audio VHF communications relating to ship operations should be recorded on an additional separate channel to those referred to in the point above.
  • RADAR- Recording of the main displays of both ship’s radar installations as required by SOLAS regulations.
  • AIS- All AIS data should be recorded.
  • ECDIS display in use at the time as the primary means of navigation.
  • Rolling Motion- VDR should be connected to an electronic inclinometer if installed.
  • Configuration data: In addition to the data items, a data block defining the configuration of the VDR and the sensors to which it is connected should be written into the final recording medium during the commissioning of the VDR.
  • Electronic Logbook: Where a ship is fitted with an electronic logbook in accordance with the standards of the Organization the information from this should be recorded.

Additionally, the following requirements shall be fulfilled by the VDRs installed after July 1st, 2014:

The final recording medium should consist of the following items:
a) Fixed Recording Medium:

  • Data recorded for 48 Hrs and continuously overwritten with new data
  • should maintain the recorded data for a period of at least two years following the termination of the recording.

b) Float-free Recording Medium:

  • Data recorded for 48 Hrs and continuously overwritten with new data
  • should maintain the recorded data for a period of at least six months following termination of recording;

c) Long-term Recording Medium:

  • Data recorded for 30 days/ 720 Hrs and continuously overwritten with new data
  • be capable of being accessed from an internal, easily accessible area of the ship;

Components of VDR

Components of Voyage Data Recorder

Data Management Unit: This data, which comprises of voices, various navigational parameters, ship’s location, etc. are fed to a unit called the Data Management Unit. The data collected by the Data Management Unit is digitalized, compressed, and is stored in a specified format in a protective storage unit, called
Final Recording Medium” which is mounted in a safe place.

Audio Module: It consists of an audio mixer for recording audio from microphones placed in the wheelhouse, bridge wings, ECR, and various other locations. VHF audio signals are also interfaced
with this unit.

Final Recording Unit: The final recording module, also sometimes called VDR CAPSULE, comprises of a tamper-proof electronic storage medium(s) encased in a protecting casing. A VDR Capsule is capable of withstanding heavy weather, collisions, fires, and pressure conditions even when a ship is at a depth of several meters in water.
This tamper-proof storage unit can be a retrievable fixed type with an underwater locator or floating unit with an in-built EPIRB for early location in the event of an accident.
Properties of Final Recording Unit:

  • Highly visible color
  • Can withstand temperature up to 1100ºC
  • Can sustain deep-sea pressure of 6000 m
  • Electronically tamper-proof data
  • Easily accessible/ Float-free

Remote Alarm Module: This is a small panel connected to the Data Management Unit that will sound an audio-visual alarm should any error or fault develop in the equipment or if the sensor inputs are missing.

Replay Station: The VDR should provide an interface for downloading the stored data and playback the information to an external computer. The interface should be compatible with an internationally recognized format, such as Ethernet, USB, FireWire, or equivalent.
A playback software should be provided with VDR with the capability to download the stored data and playback the information. The software should be compatible with an operating system available with commercial off-the-shelf laptop computers and where non-standard or proprietary formats are used for storing the data in the VDR, the software should convert the stored data into open industry-standard formats.

Power Source: The VDR should be capable of operating from the ship’s main and emergency source of electric power.

If the ship’s source of electrical power supply fails, the VDR should continue to record Bridge Audio from the dedicated reserve power source for a period of 2 hours. At the end of this 2 hour period, all recording should cease automatically.

S-VDR (Simplified Voyage Data Recorder)


An S-VDR (Simplified VDR) is the same as a VDR. There is no principle
difference between a VDR and an S-VDR except for the amount of information required to be recorded by S-VDR is less.

Data Recorded by S-VDR

  • Date and time; preferably external to ship (e.g. GNSS)
  • Ship’s position from the electronic positioning system
  • SOG and/or STW from Ship’s SDME
  • Heading from Ship’s compass
  • Bridge Audio from one or more bridge microphones
  • Communications audio from VHF communications
  • Radar data: post-display selection from Master Radar display
  • AIS Data to be recorded if it is impossible to record Radar data. If Radar is recorded then AISmay be recorded as an additional source of information
  • Other items to be recorded when additional items for VDR when interfacing is available.

Carriage Requirements

The MSC at its 79th session in December 2004 adopted amendments to regulation 20 of SOLAS chapter V (Safety of Navigation) on a phased-in carriage requirement for a shipborne simplified voyage data recorder (S-VDR). The amendment entered into force on 1 July 2006.

The regulation requires a VDR, which may be an S-VDR, to be fitted on existing cargo ships of 3,000 gross tonnage and upwards, phasing in the requirement for cargo ships of 20,000 gross tonnage and upwards first, to be followed by cargo ships of 3,000 gross tonnage and upwards.

The S-VDR 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.

The phase-in is as follows:

  • To assist in casualty investigations, cargo ships, when engaged on international voyages, shall be fitted with a VDR which may be a simplified voyage data recorder (S-VDR) as follows:
  • in the case of cargo ships of 20,000 GRT and upwards constructed before 1 July 2002, at the first scheduled dry-docking after 1 July 2006 but not later than 1 July 2009;
    in the case of cargo ships of 3,000 GRT and upwards but less than 20,000 GRT constructed before 1 July 2002, at the first scheduled dry-docking after 1 July 2007 but not later than 1 July 2010; and
  • Administrations may exempt cargo ships from the application of the requirements when such ships will be taken permanently out of service within two years after the implementation date specified above.

Comparison of VDR and S-VDR