VDES and NAVDAT: the Next Generation of Digital Maritime Communications
The VHF channel we knew as voice-only becomes a data channel too: two new systems enter the SOLAS framework for ship-shore digital information exchange and safety broadcast transmission.
Operational Explanation
The NCSR (Navigation, Communications and Search and Rescue) sub-committee finalised, at its NCSR 12 (May 2025) and NCSR 13 (June 2026) sessions, the technical framework for two new maritime digital communication systems. VDES (VHF Data Exchange System) introduces digital data exchange over the VHF channel, on a voluntary basis, through amendments to SOLAS Chapter V: adopted at MSC 111 (May 2026), with entry into force expected from 1 January 2028. NAVDAT is instead a shore-to-ship digital broadcast transmission system for maritime safety and search-and-rescue information, with the manual and technical roadmap being finalised.
NCSR 13 also finalised the MSC circular on the transition scheme for digital VHF voice communications, with a roadmap that keeps the existing GMDSS safety channels in place during the introduction of digital capability.
31 December 2026 is not a deadline for the ship
There is no “mandatory MSI reception through all recognized operational RMSS by the end of 2026”. That obligation does not exist. The deadline is real, but it sits at the other end of the link.
MSC 108 (May 2024) agreed that maritime safety information should be disseminated through all recognized mobile satellite services (RMSS) in operation by 31 December 2026. The commitment falls on MSI providers and the States responsible for dissemination: in practice, completing publication on services other than the historic one. It is an implementation target, not a convention requirement.
What SOLAS asks of the ship, by contrast. Chapter IV, replaced in its entirety by resolution MSC.496(105) and in force since 1 January 2024, says at Regulation IV/7.1.4 that every ship shall be provided with “a receiver or receivers capable of receiving MSI and search and rescue related information throughout the entire voyage in which the ship is engaged”. A receiver, or more than one, capable of receiving MSI for the whole voyage: no number of satellite services, no multi-RMSS reception obligation. Across Regulations IV/7–IV/11 the phrase recognized mobile satellite service always appears in the singular, and always in a transmitting or alert-watch function.
The amendments that bring the dissemination obligation into the Convention — Regulations IV/5, V/4 and V/5 — were approved at MSC 110 (June 2025) and adopted at MSC 111 (May 2026), entering into force on 1 January 2028. There too, the obligation is one of dissemination. Declared limit: for the MSC 108 decision on 31 December 2026 we found no verbatim wording in an IMO document; we take it from four concurring independent sources — the Liberian Registry, DNV, the US Coast Guard GMDSS Task Force and Lloyd's Register. For the 1 January 2028 entry into force we do not have the MSC 111 resolution number: it does not appear in the IMO list of amendments updated to 3 July 2026, and the classification societies' session summaries are the only source we opened.
The practical advice remains true and useful: checking that the on-board equipment can receive from more than one RMSS is good practice, because from 2027 a notice may be published on a service other than the one the Company holds a long-standing contract with. But it is operational prudence, not a prescription: calling it an obligation sends people looking on board for a non-conformity the PSCO cannot raise.
Regulatory Reference
SOLAS Chapter V (NCSR 12/13 amendments, adopted at MSC 111, May 2026): voluntary introduction of VDES, in force from 1 January 2028. SOLAS Chapter IV, replaced by res. MSC.496(105) and in force since 1 January 2024: Regulation IV/7.1.4 asks the ship for “a receiver or receivers capable of receiving MSI” — no multi-RMSS reception obligation. Regulations IV/5, V/4 and V/5, amended at MSC 111 (May 2026) with entry into force 1 January 2028: obligation to disseminate MSI and SAR-related information through all operational RMSS. Distinct from both, the 31 December 2026 implementation target agreed at MSC 108, falling on MSI providers. NAVDAT: manual and roadmap being finalised, approval expected at MSC 112 (December 2026); carriage of NAVDAT equipment is not mandated by SOLAS.
Scope of Application
Every ship subject to SOLAS Chapters IV and V. VDES applies on a voluntary basis from 2028, as an alternative to AIS. On MSI reception the ship remains subject to Regulation IV/7.1.4 as replaced in 2024: a receiver, or more than one, capable of receiving MSI for the whole voyage. The 31 December 2026 target and the 2028 amendments concern dissemination, and therefore providers and States, not shipborne equipment.
Procedure / How to Complete It
- Monitor publication of the consolidated text of the SOLAS Chapter V amendments on VDES, ahead of voluntary entry into force from 2028.
- Verify that on-board equipment can receive MSI from RMSS providers other than the one historically installed. It is not a convention obligation — Regulation IV/7.1.4 does not impose it — but from 2027 a notice may arrive on a service other than the usual one, and a ship that does not receive it has no non-conformity: it has one notice fewer.
- Follow the transition scheme for digital VHF voice communications published by NCSR 13, maintaining full familiarity with the existing GMDSS safety channels during the digital introduction phase.
- Train officers of the watch on the distinction between existing systems (traditional GMDSS) and new digital capabilities (VDES, NAVDAT) as soon as they become commercially available.
- Coordinate with the on-board equipment supplier to understand the timeline for commercial availability of the new VDES/NAVDAT capabilities.
Practical Example
Example: a Company verifies that its fleet's satellite equipment can receive maritime safety information from RMSS providers other than the long-standing contracted one. It does so because from 2027 providers will publish on every operational service, not because a rule requires it: in a PSC inspection that check has no box, but at sea a safety notice not received still counts.
What Typically Goes Wrong
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| The 31 December 2026 target read as a shipboard deadline, and multi-RMSS reception treated as an obligation of the ship | People look on board for a compliance no Regulation prescribes (IV/7.1.4 asks only for “a receiver or receivers”), while losing sight of the one real convention date: 1 January 2028 for Regulations IV/5, V/4 and V/5 | Keep the three dates apart: 1 January 2024, modernized Chapter IV already in force; 31 December 2026, implementation target for MSI providers; 1 January 2028, convention obligation to disseminate through all RMSS |
| Introduction of new digital capabilities (VDES, NAVDAT) confused with a replacement of the existing GMDSS safety channels | Mistaken underestimation of the importance of maintaining full familiarity with traditional safety channels during the transition | Treat VDES and NAVDAT as additional capabilities, not substitutes for the existing GMDSS safety channels, until the transition is complete |
What the PSCO Checks
Operational Tips
- Do verify the multi-RMSS compatibility of on-board satellite equipment, but knowing what it is: operational prudence, not compliance. If someone in the Company presents it as an obligation with a 31 December 2026 deadline, they are reading an MSI providers' target as though it were a shipboard rule.
- Follow publication of the consolidated SOLAS text on VDES and finalisation of the NAVDAT manual (expected at MSC 112, December 2026) to plan fleet upgrades ahead of time.
- Do not treat the new digital capabilities as substitutes for the existing GMDSS safety channels: they are additional capabilities during a long-term transition phase.
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.
- MSI reception compliant with Regulation IV/7.1.4: receiver (or receivers) capable of receiving MSI throughout the intended voyage
- Compatibility with more than one RMSS verified as good practice, not as a requirement
- Consolidated SOLAS Chapter V text on VDES monitored ahead of the 2028 entry into force
- Finalisation of the NAVDAT manual monitored (expected MSC 112, December 2026)
- Officers of the watch trained on the distinction between existing GMDSS systems and new digital capabilities
- Traditional GMDSS safety channels kept fully operational during the transition
FAQ
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Last substantive revision of this page: 19 August 2026 · page fingerprint ba0f10cd1d90