A typical Simplified Voyage Data Recorder (S-VDR)

The S-VDR collects data from the sensors on board the vessel, it digitises, compresses and stores this information in an externally mounted Crash Survivable Module (CSM) or float-free module. The data storage is a tamper-proof unit designed to be easily recovered in the event of a maritime incident, enabling the data to be replayed for investigative purposes.