Voyage Data Recorders (VDRs) are a crucially important component onboard ships around the world. They are rightly referred to, as the ‘Black Box’ of ships! In this article, we would be explaining you everything you need to know about Voyage Data Recorders.
Definition of Voyage Data Recorder (VDR)
Voyage data recorder (VDR) is generally a two-part system comprising of a data collecting unit and a protected storage unit which accumulates the retrieved data. The IMO specifies VDR as a complete system, comprising any items required to associate with the sources of input signals, their processing and encoding, the final recording medium, the playback equipment, the power supply and a reserve power source.
Corresponding to black box on airplanes, VDR is an equipment that is onboard a ship which records several data on a ship which may be used for rebuilding of the ship details and crucial information amidst accident investigation.
The important part of this system is carried inside the ship and attached to a deck-mounted protective capsule which houses a fixed high-capacity solid state memory block. The capsule is used to resist fire, shock, deep sea pressure and penetration.
VDR consistently records 12 hours of ship’s activity which includes ship position, date & time, physical status, speed, bridge audio, radar information which shows the actual radar image at the time of recording, engine order & response, fire doors and watertight status, status of hull opening, wind speed and direction. Above information is used during the investigation to recognize the reason of accident. Not only for the investigation during an accident, but it is also used for maintenance, performance efficiency and training activity to enhance safety and decrease running costs. VDR of a ship is better than the black box of an airplane because it stores several data and for a period of at least 12 hours (VDR’s installed post-July 2014).
Working of VDR
The VDR are categorized in two types:
- Data collection unit (DCU)
- Data recording unit (DRU)
The Data collection unit (DCU) is located on the bridge that extracts data from all integrated sources. While the Data recording unit (DRU) is situated on the monkey island which stores the data which is recorded through the unit inside the wheelhouse. The DCU comprises backup batteries, interface modules and Data processor unit. According to the standards set by IMO and IEC, collection of data is done by sensors. If the power of a main ship fails, power is supplied with the use of batteries to the DCU to record bilge audio for 2 hours. The data which is coming from DCU is stored by the flash memory in the DRU. The components of DRU are symbolized in the protective capsule. After the accident, capsule makes sure the recovery and the survival of the data recorded.
Collection of data is done from all the sources as discussed above and it is kept in the capsule for 12 hours (or 48 hours) and unceasingly refreshed as the voyage continues. A record button is available in the bridge unit, so after pushing the button (for instance during beginning of an accident), a new set of information will be recorded by the recorder from that time.
Operational Requirements For VDR
The VDR must consistently maintain the records of pre-selected data items connecting to the status and output of the ship’s equipment and control & command on ship. For allowing subsequent scrutiny of factors surrounding an accident, the technique of recording must ensure that the several data items can be corresponded in date and time during playback on capable equipment. A performance test can be conducted any time for that, the system must comprise several functions. With the help of playback equipment, this test can be conducted and also must be sure that all the necessary data items are recorded correctly.
What Does VDR Record?
Following are the important aspects onboard ships, which are recorded by Voyage Data Recorders (VDR):
- Bridge audio (SVDR)
- Radar data (SVDR)
- ECDIS data (SVDR)
- Communication audio (audio) (SVDR)
- Echo sounder
- Main alarms
- Ship’s position
- Status of hull opening (doors)
- Hull stresses
- Speed and acceleration
- Date and time (SVDR)
- Wind speed and direction
- Watertight and fire door status
- Speed and heading
- Rudder order and response
Maintenance of VDR
For proper operation of any electronic systems, maintenance is very important. For maintenance check, only certified personnel must work inside the equipment. About the routine checks, one must inspect the cables for signs of damage and inspect that all the connections are firm. Also, the battery must be replaced after every 4 years, while a qualified and certified service engineer should replace the backup battery with the new one. Regulation 18.8 of SOLAS Chapter V articulates the requirements for maintenance. Onboard a ship, a certificate has to be retained stating that the results of all the tests were acceptable and satisfactory.
Simplified Voyage Data Recorder (S-VDR)
A S-VDR is an equipment which records information that is very necessary and valuable & does not record information as substantial as VDR. S-VDR is more in usage on board a ship as it is cost-effective. To understand the concept of S-VDR, we must compare the data with that of VDR. Only necessary information to be recorded are marked next to the category above. If there are standard interfaces available, the least two interfaces of ECDIS and radar are likely to be recorded.