VDR is the equivalent of a ship’s black box of an aeroplane. It tracks the events of a maritime incident such as the time and date of the incident, the location of the vessel at the moment of the accident, its speed, course and more. The data recorded is an important resource for identifying safety risks and enhancing the operation of the ship.
According to IMO regulations, the standard VDR is required to record an array of data. These include the following: date and time referenced to Coordinated Universal Time (UTC) vessels’ position (latitude and longitude), coordinate reference) along with speed and heading as well as bridge audio (acquisition of voice messages recorded by a microphone or two located on the bridge in order to record conversations and sound alarms) and VHF radio communications (VHF) and radar data (a exact replica of the display that was on view at the time of the recording), rudder order and response, engine order and response watertight doors, their status, as well as accelerations and hull stresses.
The system is composed of a concentrator which process and encodes data streams, sensors which input data to the concentrator and the final recording media (FRM) which can withstand accidents and permit the retrieval of the voyage data. The FRM could be a fixed device mounted on the vessel or a retrievable floating device connected to the EPIRB to allow for the identification of the vessel quickly in the event of a catastrophe.
The most efficient way to ensure the integrity of the vdr system is make its use an integral part of all bridge drills and training for the crew. The data saved can be used to identify areas in need of training and to improve bridge procedures and operational security.
http://www.digitaldealdataroom.info/what-is-the-purpose-of-a-data-audit/