VDR (Voyage Data Recorder)
The ship's 'black box': what it actually records, when it must be checked, and why its proper maintenance is often neglected until it is needed — too late.
Operational Explanation
The Voyage Data Recorder (VDR) continuously records critical navigational data (position, heading, speed, bridge radio and VHF communications, radar images, AIS data, alarms, and helm and engine commands) for a minimum period, enabling reconstruction of events in the event of an incident.
How many hours, in fact: it depends on when the VDR was installed
“A minimum period” is not an operational figure. The figures exist, and there are two different sets, because the criterion is not the age of the ship but the date the equipment was installed. Res. MSC.333(90) says so itself, recommending that Governments ensure VDRs “if installed on or after 1 July 2014, conform to performance standards not inferior to those specified in the annex to the present resolution” and, if installed earlier, to the preceding standard. There is no mandatory retrofit: in 2026 there are still ships whose VDR lawfully retains twelve hours.
| VDR installed | Standard | What it retains |
|---|---|---|
| before 1 July 2014 | Res. A.861(20), §5.3.3 (for S-VDRs: Res. MSC.163(78), same paragraph) | “at least 12 h” on a single final recording medium |
| from 1 July 2014 | Res. MSC.333(90), §5.4.3 | “at least 30 days/720 hours on the long-term recording medium and at least 48 hours on the fixed and float-free recording media” |
| from 1 July 2022 | MSC.333(90) as amended by MSC.494(104) | the same durations, plus the requirement for the float-free capsule to maintain the recorded data for at least six months following termination of recording |
The last two rows are the difference between recoverable data and lost data: twelve hours are used up in the time it takes to reach an anchorage, thirty days are not. And the six months of MSC.494(104) are something else again from the 48 hours: 48 hours is the recording window retained, six months is the physical survival of the data after recording has stopped.
After an incident: who saves the data, and with how much margin
SOLAS sets no hourly deadline for saving the data. There is a guideline, MSC/Circ.1024, and a qualitative criterion: “Recovery of the VDR information should be undertaken as soon as possible after an accident to best preserve the relevant evidence”. Responsibility rests with the owner, “through its on-board standing orders”; the Master acts “where time and other responsibilities permit”. So the real deadline is not set by the rule: it is set by the overwrite cycle of the equipment actually installed, which is one more reason to know which of the two standards applies to your ship.
A VDR that is installed but not functioning correctly, or whose data cannot be retrieved when needed, defeats the entire purpose of the equipment: maintenance and periodic verification (including the annual performance test) are just as important as the initial installation.
2026 update — electronic inclinometers connected to the VDR: Resolution MSC.532(107) introduces the new paragraph SOLAS Regulation V/19.2.12, which requires the installation of an electronic inclinometer on board new container ships and bulk carriers of 3,000 gross tonnage and above with keel laid on or after 1 January 2026. The instrument, type-approved to the performance standards of Resolution MSC.363(92), must determine, display and record the ship's rolling motion, supplying the VDR with additional data useful both for real-time decision-making on trim and operational stability, and for post-incident reconstruction in casualties involving cargo shift, container loss or dynamic separation of bulk cargo. The new requirement does not apply to existing ships, nor to cargo ships that carry bulk cargo only occasionally, nor to general cargo ships carrying containers on deck only.
Regulatory Reference
SOLAS Chapter V, Regulation 20 (Voyage Data Recorders): installation required for passenger ships and cargo ships according to applicable tonnage thresholds — the S-VDR is admissible only for cargo ships constructed before 1 July 2002. Retention: Res. A.861(20), §5.3.3, twelve hours for VDRs installed before 1 July 2014; Res. MSC.333(90), §5.4.3, 48 hours on the fixed and float-free capsules and 30 days on the long-term recording medium for those installed later. SOLAS V/18.8 for the annual check: the system “shall be subjected to an annual performance test” conducted by an “approved testing or servicing facility” to verify “the accuracy, duration and recoverability of the recorded data”, with a copy of the certificate of compliance retained on board; procedure in MSC.1/Circ.1222/Rev.1. Recovery of data after an incident: MSC/Circ.1024. Performance standards under Resolution MSC.333(90), as amended by MSC.494(104), for VDRs installed on or after 1 July 2022. Annual performance test required by an authorised organization. SOLAS Regulation V/19.2.12 (Res. MSC.532(107)), in force from 1 January 2026: electronic inclinometer connected to the VDR required for new container ships and bulk carriers ≥3,000 GT with keel laid on or after that date, type-approved to Res. MSC.363(92).
Scope of Application
Passenger ships regardless of build date, and cargo ships of gross tonnage at or above the applicable thresholds, according to the SOLAS V/20 phase-in schedule.
Procedure / How to Complete It
- Verify that the VDR is operating continuously during navigation, recording all required channels (position, communications, radar images, AIS data).
- Carry out the annual performance test through an authorised organization, verifying the integrity and readability of the recorded data.
- Periodically check the protective capsule (fixed or float-free) and the underwater locating device associated with the VDR.
- In the event of an incident or significant near-miss, immediately safeguard the VDR data for the relevant period, before it is overwritten by the continuous recording cycle.
- Keep documentation of the last annual performance test on board, available for PSC verification.
- For new container ships and bulk carriers ≥3,000 GT with keel laid on or after 1 January 2026, verify installation and correct operation of the electronic inclinometer connected to the VDR, type-approved to Resolution MSC.363(92).
Practical Example
After a near-grounding, the officer of the watch's first question is not “how many hours do I save” but which standard my VDR carries: the answer is on the certificate of compliance from the last annual performance test, kept on board. If the VDR predates 1 July 2014, the useful window is twelve hours and saving is urgent in the literal sense. If it is later, the long-term recording medium holds thirty days: the urgency remains — the fixed and float-free capsules stop at 48 hours — but there is margin to do it properly, downloading the whole period instead of a fragment chosen under pressure.
What Typically Goes Wrong
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| Annual performance test not carried out or overdue | PSC deficiency, risk that the VDR will not function correctly when needed | Schedule the annual performance test together with the other statutory surveys, without delay |
| VDR data not promptly safeguarded after an incident or near-miss | Permanent loss of information critical to the investigation, through overwriting by the continuous recording cycle | Train the crew to immediately safeguard the relevant data after every significant event |
| Protective capsule or underwater locating device not periodically checked | Inability to recover data in the event of loss of the ship | Include verification of the capsule and locating device in the periodic maintenance programme |
What the PSCO Checks
Operational Tips
- Do not treat the annual performance test as a minor formality: always verify its actual outcome, not just its formal completion.
- Train the crew to immediately safeguard VDR data after every significant event, without waiting for instructions from the Company.
- Include the protective capsule and underwater locating device in the periodic maintenance programme, not just the recorder itself.
Preparation checklist
Educational checklist. This summary supports learning and preparation only. It does not replace the vessel’s approved procedures, manuals, statutory documents, company SMS, or applicable official requirements. Completing it demonstrates neither compliance nor readiness for an inspection: it shows that a list has been read, not that the ship is in order. Always verify the current documents carried on board.
- VDR operating continuously with all required channels active
- Annual performance test carried out and documented
- Protective capsule and underwater locating device periodically checked
- Post-incident data safeguarding procedure known to the crew
- Documentation of the last test available on board for PSC verification
- For new ships subject to the requirement (container ships/bulk carriers ≥3,000 GT, keel laid from 2026): electronic inclinometer installed, functioning and connected to the VDR
FAQ
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Last substantive revision of this page: 19 August 2026 · page fingerprint 898f9eb03c01