MASS Code: What the IMO Just Imposed on Your Ship Safety Management System

On 22 May 2026, the IMO Maritime Safety Committee (MSC 111) adopted the MASS Code — the first international regulatory framework dedicated to Maritime Autonomous Surface Ships. This is not a future scenario. It is maritime law in the making, with concrete implications for your Safety Management System today.

What is the MASS Code?

The MASS Code (International Code of Safety for Maritime Autonomous Surface Ships) is the first global regulatory framework covering autonomous and remotely operated vessels. It is the result of nearly a decade of work by the International Maritime Organization, which launched its regulatory scoping exercise in 2017.

Its objective: to ensure that autonomous and remotely operated ships achieve a level of safety, security, and environmental protection equivalent to that of conventional vessels. It applies to cargo ships and enters into force on 1 July 2026 as a non-mandatory instrument. The mandatory version will enter into force on 1 January 2032.

Between now and then: an Experience Building Phase (EBP), during which operational data from MASS in service will be collected worldwide. Drafting of the mandatory code begins in 2028 — that is the critical date, not 2032.

The Four Degrees of Autonomy Recognised by the IMO

The MASS Code is the first international instrument to formalise a four-tier classification of autonomy for commercial vessels. This framework now stands as the global regulatory reference.

• Degree 1 — Ship with automated processes and decision support. Seafarers are on board and in full control of all operations. This covers the vast majority of modern commercial vessels today.

• Degree 2 — Remotely controlled ship with seafarers on board. The ship can be operated from a Remote Operation Centre (ROC) ashore, but a reduced crew remains on board. Control is partially delegated.

• Degree 3 — Remotely controlled ship without seafarers on board. The ship operates with no crew aboard, under continuous supervision from an ROC. This degree carries specific requirements around cybersecurity, system redundancy, and autonomous emergency procedures.

• Degree 4 — Fully autonomous ship. The ship makes its own decisions without direct human intervention. This degree remains largely experimental.

Most ship operators currently operate at Degree 1, sometimes approaching Degree 2. The immediate challenge of the MASS Code is not about reaching Degree 3 or 4 — it is about documenting where you stand today and what that means for your operational procedures.

Master’s Responsibility: A Non-Negotiable Principle

“The master remains legally responsible for the ship, whether on board or operating from a Remote Operation Centre ashore.” — Core principle of the MASS Code, adopted at MSC 111

This is the most important — and most misunderstood — principle of the MASS Code. The IMO has been explicit: regardless of the technology on board, regardless of the degree of automation, the chain of responsibility remains attached to an identifiable individual. It may shift geographically — the master may operate from a shore-based centre — but it does not dissolve.

For technical superintendents and fleet managers, this raises an immediate operational question: does your SMS clearly document who decides what? Under what conditions can a decision be delegated to an automated system? If the answer is no, that is a compliance risk — even today.

What the MASS Code Requires from Your SMS Right Now

The MASS Code will not wait until 2032 to affect your organisation. Three concrete workstreams emerge for your Safety Management System.

Map human vs automated decisions. Every procedure that delegates a decision to an on-board system must be identified. Navigation, propulsion, stability management, alarm systems: for each critical function, who — or what — makes the final call? This mapping exercise is not a formal obligation before 2032, but it is exactly what PSC inspectors and ISM auditors will look for once SOLAS amendments enter the drafting phase from 2028.

Update your emergency procedures. From Degree 2 onwards, your SMS must anticipate scenarios where the ROC connection is lost. Who takes over? With what procedure? These questions need documented, tested answers.

Contribute to the Experience Building Phase. The EBP is a concrete opportunity for proactive ship operators. Documenting your automation practices today — on-board systems, human-machine interfaces, sensor data — means actively shaping the mandatory code due in 2032. And being far better prepared to comply with it.

The Regulatory Timeline You Cannot Afford to Confuse

The adoption of the MASS Code at MSC 111 (13–22 May 2026) marks a first milestone. Here are the key dates to integrate into your regulatory planning.

• 1 July 2026 — MASS Code enters into force (voluntary instrument). Flag states may begin applying it.

• 2026–2030 — Experience Building Phase (EBP). Global collection of operational data from MASS in service.

• 2028 — Mandatory code drafting begins + SOLAS amendments. This is the pivotal date for ship operators.

• 1 July 2030 — Expected adoption of the mandatory code.

• 1 January 2032 — Mandatory MASS Code enters into force.

2028 is the critical date, not 2032. That is when technical trade-offs become legal obligations. Operators who have documented their practices during the EBP will hold a decisive advantage when the mandatory drafting phase begins.

Maintenance and CMMS: Autonomy Changes Your Entire Intervention Chain

Maritime autonomy does not only affect the bridge. It touches every function on board — including maintenance.

A Degree 2 or 3 vessel is equipped with automated monitoring systems: engine sensors, level alarms, propulsion monitoring. These systems generate continuous operational data. For that data to carry regulatory weight during a PSC inspection, an ISM audit, or an accident investigation, it must be integrated into a structured traceability system — not stored in isolated logs or reconstructed after the fact in spreadsheets.

The boundary between an automatically detected anomaly and a manually decided human intervention must be traceable, timestamped, and archived. This is precisely where maritime CMMS stops being a convenience tool and becomes a compliance tool.

Preparing Your SMS for the MASS Code with BoatOn Book

BoatOn Book integrates maritime CMMS, digital logbook, and ISM procedure tracking in a single interface designed for vessels between 15 and 150 metres. In the context of the MASS Code, this translates into direct operational advantages.

• Logging human interventions in the digital logbook creates a clear audit trail distinguishing crew decisions from automated triggers.

• Structuring SMS procedures around the four degrees of autonomy makes ISM audits faster and adaptation to evolving MASS Code requirements straightforward.

• Archiving maintenance data with timestamps and crew validation creates audit-ready traceability, fully compatible with EBP requirements and PSC expectations.

If your preventive maintenance programme is not yet structured in a CMMS, now is the right time to act — before the regulatory pressure of 2028 turns that decision into an emergency.

Key Takeaways

The MASS Code is not a 2032 topic. It is the signal that the regulatory framework for maritime autonomy is now set — and that operators who document their practices today will hold a decisive head start.

The first question to ask: does my SMS clearly distinguish between human decisions and automated decisions? If not, that is where to start.

To go further, the BoatOn Consulting team can support you in auditing your SMS and progressively aligning with the MASS Code.