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Voyage Data Recorder (VDR)

Explanation of Voyage Data Recorder (VDR):

  • A VDR or voyage data recorder is an instrument installed on a ship to continuously record vital information related to the operation of a vessel.
  • It contains a voice recording system for a period of at least last 12 hours.
  • This recording is recovered and made use of for investigation in events of accidents.
  • The data records covering the last 12 hours are continuously overwritten by the latest data.
  • A VDR is capable of withstanding heavy weather, collisions, fires and pressure conditions even when a ship is at a depth of several meters in water.
Voyage Data Recorder (VDR)
Voyage Data Recorder (VDR)

Working of VDR:

  • There are various sensors placed on bridge of the ship and on prominent location from which the required data is continuously collected.
  • This data which comprises of voices, various parameters, ships location etc. are then fed to a storage unit where the whole input is recorded and saved for at least 12 hours.
  • There is also a record button provided in the bridge unit so that after pushing button (say during starting of any incident like collision or grounding), the recorder will start recording new set of information from that period of time.
  • The data collected by VDR is digitalised, 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 accident.

Main Components of VDR:

  • Data Management Unit: It acquires data from various sources using interfaces, processes and stores the data in a specified format.
  • 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 can also be interfaced with this unit.
  • Final Recording Unit:
    • This is a fire resistant, pressure tight storage medium to store recorded data.
    • The capsule is resistant against shock, penetration, fire, deep sea pressure and immersion. Housed in a highly visible protective capsule which can withstand high temperatures (1100OC) and deep sea pressure of 6000 m.
  • Remote Alarm Module: This is a small panel connected to the Data Management Unit that will sound an alarm should any error or fault develop in the equipment.
  • Replay Station:
    • This is an optional module for downloading and replaying the recorded data.
    • The data when played back can help in casualty investigations as well as for self analysis.
  • Information Recorded:-
    • Date & Time from GPS every 1s
    • Position & Datum – Lat/Long and datum from GPS, Loran-C etc. The source of data is identified on playback.
    • Speed (water / ground) recorded every 1s to 0.1k resolution
    • Heading (gyro or magnetic) is recorded at intervals of 1s to a resolution of 0.1 deg
    • Auto pilot settings for speed, latitude, rudder limit, off-course alarms etc.
    • Bridge audio in real time, both internal & external (150-6000Hz). The mic test beeps every 12 hrs & this is recorded.
    • Radar image recorded every 15s includes range rings, EBLs, VRMs, radar maps, parts of SENC & other essential navigational indications.
    • Wind speed/direction from the Anemometer is recorded & stored individually with time stamps.
    • VHF communication from 2 VHFs are recorded for both transmitted and received audio signals. Audio is compressed and labeled VHF 1 & VHF 2.
    • Hull openings & watertight doors status is received every 1s and stored with time stamps
    • Hull stresses are received and stored with time stamps.
    • Thruster status (bow/stern) can be recorded for their order and response
    • Rudder order and response angle is recorded to a resolution of 1 deg
    • Engine order and response from the telegraph or direct engine control with shaft revolution and ahead and astern indicators are recorded to a resolution of 1 rpm
    • AIS target data is recorded as a source of information regarding other ships.
    • Alarms are recorded with time stamps. All IMO mandatory alarms as well as other audible alarms are stored individually by the bridge audio microphones.

Purpose of VDR:

  • The main purpose of VDR is to record and store ship’s critical parameters to facilitate reconstruction of the incident for the purpose of analysis
  • Additionally navigator can use this for self-analysis, as lessons-learning tool and thus improvement of procedures in the future.
  • VDR can be used to identify cause of an accident and thus make major contribution to maritime safety.
    • The benefits are:
    • Promotion of safe practices
    • Accident investigation and enquiry
    • Response assessment and study
    • Training aid and support
    • Reduction in insurance costs
    • Statistics generation

VOYAGE DATA RECORDER – DATA ITEMS TO BE RECORDED:- IMO Performance Standard (Res. A.861(20)) and IEC Information format (IEC 61996).

DATA ITEM SOURCE
Date & Time Preferably external to ship (e.g.GNSS)
Ship’s position Electronic Positioning system
Speed (through water or over ground) Ship’s SDME
Heading Ship’s compass
Bridge Audio 1 or more bridge microphones
Comms. Audio VHF
Radar data- post display selection Master radar display
Water depth Echo Sounder
Main alarms All mandatory alarms on bridge
Rudder order & response Steering gear & autopilot
Engine order & response Telegraphs, controls and thrusters
Hull openings status All mandatory status information displayed on bridge
Watertight & fire door status All mandatory status information displayed on bridge
Acceleration & hull stresses Hull stress and response monitoring equipment where fitted
Wind speed & direction Anemometer when fitted

Recovery of VDR: Recovery of the VDR is conditional on the accessibility of the VDR or the data contained therein.

  • In the case of a non-catastrophic accident, recovery of the memory should be straightforward. For example, in some VDRs it can be accomplished by removal of a hard disc from the VDR unit. This action will have to be taken soon after the accident to best preserve the relevant evidence for use by both the investigator and the ship owner. As the investigator is very unlikely to be in a position to instigate this action soon enough after the accident, the owner must be responsible, through its on-board standing orders, for ensuring the timely preservation of this evidence in this circumstance.
  • In the case of abandonment of a vessel during an emergency, masters should, where time and other responsibilities permit, recover the memory and remove it to a place of safety and preserve it until it can be passed to the investigator.
  • In the case of a catastrophic accident, where the VDR is inaccessible and the data has not been retrieved prior to abandonment, a decision will need to be taken by the Flag State in co-operation with any other substantially interested States on the viability and cost of recovering the VDR balanced against the potential use of the information. If it is decided to recover the VDR the investigator should be responsible for co-ordinating its recovery. The possibility of the capsule having sustained damage must be considered and specialist expertise will be required to ensure the best chance of recovering and preserving the evidence. In addition the assistance and co-operation of the owners, insurers and the manufacturers of the VDR and those of the protective capsule may be required.