Voyage Data Recorder

The Voyage Data Recorder captures a comprehensive record of what is happening on and around a ship so that, if an accident occurs, investigators can reconstruct the sequence of events and understand its causes. Required by SOLAS on many ships, it is the marine counterpart of the aviation black box, and its purpose is safety improvement: by learning accurately what went wrong, the industry can prevent similar accidents in future. It also protects crews and companies by providing objective evidence rather than relying on memory and conflicting accounts.

A VDR records a wide range of parameters continuously. These typically include audio from microphones on the bridge and from the VHF radio, the radar and ECDIS display images, the ship's position, heading and speed, rudder and engine orders and responses, depth under the keel, wind data, and the status of alarms, watertight and fire doors. All of this is time-stamped and stored so that the final period before an incident (the most important window) is preserved. Data is held in a protected capsule designed to survive fire, pressure and impact, and often also streamed to a float-free unit so it can be recovered even if the ship sinks.

The recorder keeps a rolling record covering a defined recent period, and after an incident the relevant data must be preserved by stopping the overwrite and saving it for the investigation. A simplified version, the S-VDR, records a reduced set of parameters and is fitted to some existing cargo ships. VDRs are subject to annual performance testing to confirm all sensors and recordings are working. While their primary role is accident investigation by the flag state and safety authorities, the data they hold is powerful evidence, and their presence also encourages good bridge practice, since the record is impartial and complete.