A milestone, but not one rule for every USV
On 1 July 2026, the International Maritime Organization's first International Code of Safety for Maritime Autonomous Surface Ships came into effect. Adopted in May, the non-mandatory MASS Code marks a significant change in how autonomous shipping is discussed: not simply as a technology trial, but as an operation that must be described, bounded and managed.
The scope of the Code matters. The IMO says it applies to cargo ships covered by SOLAS Chapter I—generally vessels over 500 gross tonnage on international voyages—while recommending that Member States apply it, as far as practicable, to smaller MASS.
Many USV trials, survey campaigns and coastal operations involve substantially smaller craft operating under domestic rules. The Code should therefore not be presented as if it directly governs every uncrewed vessel. Flag-state requirements, coastal-state rules, certification, port directions and the circumstances of the individual operation still need to be established.
In the UK, Workboat Code Edition 3 and its associated Maritime and Coastguard Agency guidance are particularly relevant to qualifying remotely operated unmanned vessels operating as workboats. The wider direction is nevertheless clear: autonomous operations are expected to demonstrate safety, accountability and an effective response when conditions or systems do not behave as planned.
Autonomous does not mean responsibility-free
The MASS Code retains an explicitly human element. The master remains responsible for the ship even when not on board, while remote operation centres form part of the safety-management arrangement.
UK guidance follows the same practical logic. MCA MGN 703 addresses the training and competence of remote operators. MGN 710 confirms that remotely operated unmanned vessels certified under Workboat Code Edition 3 require an implemented safety management system, with relevant documentation available at the remote operation centre.
Moving people ashore changes where work is performed. It does not remove the need for competence, watchkeeping, clear authority or tested contingency arrangements.
Start with the operating envelope
One of the most useful concepts in the MASS Code is the operating envelope: the conditions within which the vessel is designed and approved to operate. The IMO identifies factors including wind, sea state, visibility, water depth, adverse weather and day or night operations. The plan must also address what happens when those conditions are exceeded.
Marine support should be considered in the same way. A permanent escort is not automatically necessary for every mission, but neither is 'we will find a boat if something goes wrong' a complete recovery plan.
A proportionate support concept turns support from a vague emergency assumption into a defined operational control.
- Identify the mission phases in which assistance may be required.
- Define the failures or conditions that trigger intervention.
- Specify the capability needed from the assisting vessel.
- Set a realistic time within which that capability must arrive.
- Confirm who has authority to mobilise, tow, recover or terminate the operation.
Plan support around the mission phases
Launch and deployment: capture the USV's dimensions, displacement, tow points, lifting or handling arrangements, safe propulsion state, fendering needs and hazards relevant to the support crew. Deck space alone does not demonstrate that a craft can safely lift, tow or receive a particular USV.
Departure, arrival and constrained waters: a crewed escort, guard boat or line-of-sight support craft may be appropriate during departure, arrival, trials or passage through constrained and traffic-sensitive waters. Its role should be stated clearly and the support-vessel master's responsibility for safe navigation remains intact.
Offshore operations and standby: not every offshore USV needs to be shadowed continuously. A mission may instead use a pre-identified local support vessel, a defined availability window or mobilisation triggers linked to the risk assessment. Selection should consider capability and sea-route response time, not simply which vessel appears nearest on a map.
Tow, intervention and recovery: write the recovery plan before the asset is disabled or drifting. Establish how it can be approached, how propulsion is isolated, where a tow can be connected, whether it remains stable when unpowered, and whether recovery is alongside, on deck or to a safe haven.
Review and learning: close support missions with factual records—what triggered the response, what was observed, which actions were taken and what should change before the next operation. This is how a recovery plan improves rather than remaining a document written once and forgotten.
The practical hybrid fleet
A mature hybrid operation does not treat crewed and uncrewed vessels as opposing choices. It assigns each to the work it can perform safely and effectively.
The USV may carry out the planned remote mission. A local crewed vessel can be prepared for launch, escort, inspection, towage, handling or recovery when the operating plan requires it. The remote operations centre, USV operator and support-vessel master each retain defined responsibilities.
The result is not autonomy without people. It is an operation in which people, systems and vessels are positioned differently.
Build the support brief before mobilisation
Preparing the asset and recovery profile early allows prospective support to be assessed against the actual task rather than a generic vessel description. A useful uncrewed surface vessel support brief should include:
- Asset identity and responsible contacts.
- Mission area, route and operating limits.
- Current or last trusted position.
- Required service and mobilisation trigger.
- Towing, lifting and handling information.
- Expected safe state after a control or propulsion failure.
- Communications arrangements and remote-operation contacts.
- Required support-vessel capability and crew competence.
- Weather limits, safe havens and reporting requirements.
The question every campaign should answer
ARC coordinates suitable local workboats, guard vessels, pilot boats, tugs and specialist craft for planned and time-sensitive USV operations.
The MASS Code does not prescribe one support model for every autonomous vessel. It does, however, make the right operational questions harder to leave unanswered: who remains responsible, what are the limits, what happens outside them, and how will the asset be assisted when remote capability is no longer enough? Those are good questions for any USV campaign.