A Voyage Data Recorder( VDR) is like a black box for vessels, designed to continuously capture and store essential nautical and functional data. Its primary purpose is to help investigators in determining the cause of maritime accidents by furnishing critical information leading up to an incident.

 VDRs are obligatory under SOLAS Regulation V/ 20, which requires passenger ships and cargo ships of 3,000 GT and above to carry a VDR. This ensures vital data is recorded and available for analysis if a casualty or near- miss occurs.

 What VDR Records

 The VDR system captures multiple data streams, including

 Ship’s position( from GPS)

 Heading( from gyro)

 Speed( from speed log)

 Radar and ECDIS shots

 Bridge audio( via microphones)

 VHF dispatches

 Engine orders and responses

 Rudder angle

 AIS data

 Bridge alarms and events

 Status of watertight doors, hull openings, and fire doors

 new age VDRs store at least 48 hours of protected data and generally over to 30 days in a separate memory unit for extended playback.

How VDR Works – Technical Overview

 The VDR acts as a central core for recording real- time data from various shipboard systems. Here’s how it operates

1. Sensor Inputs

 The VDR is connected to multiple sensors and systems, including GPS, gyro compass, speed log, ECDIS, radar, AIS, microphones, and engine monitoring devices.

2. Signal Conversion & Processing

 These signals, which may be digital( e.g., NMEA 0183/2000) or analog, are collected and converted into a standard format by the VDR’s interface modules. Audio signals are filtered and digitized, and radar/ ECDIS shots are taken at intervals

3. Data Encoding & Compression

 Once gathered, the data is compressed to reduce file size and ensure effective storage. The system runs on a loop, continuously overwriting the oldest data with the newest.

3. Data Storage

 The Final Recording Medium( protected capsule) holds the last 48 hours of critical data and is constructed to survive fire, pressure, and impact.

 An internal storage drive stores longer- term data( generally 30 days) for playback and analysis.

4. Float- Free Capsule

 Located externally, often on the monkey island, this capsule detaches and floats free if the vessel sinks. It’s fitted with an Underwater Locator Beacon( ULB) that emits signals for at least 30 days to assist recovery.

5.Backup Power

 A dedicated Uninterrupted Power Supply( UPS) ensures the VDR keeps recording during power failure, generally for a minimum of two hours.

6. Self- Monitoring and Alarms

VDRs perform self- checks. However, visual or audible alarms are activated on the bridge to warn the Officer of the Watch, If faults occur.

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 Where VDR Equipment is Located

 Main VDR unit – generally placed on or near the bridge or in the ECR

 Microphones – Fixed overhead on the bridge to capture conversations, alarms, and VHF

 Radar/ ECDIS interface – Connected directly with bridge display systems

 Float- free capsule – Mounted outside on the bridge top or monkey island

 ULB( Underwater Beacon) – Attached to the capsule for locating wreckage

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 Maintenance & Testing

 Weekly performance checks( as per ISM)

 Regular testing of ULB battery and capsule status

 Verifying proper audio recording

 Software updates( if applicable)

 Logbook entries for any failures or maintenance

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 VDR Data – Beyond Accidents

 While VDRs are primarily forpost-incident analysis, they also help with

 Internal audits and safety reviews

 Navigational performance assessments

 Bridge team evaluations