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Guidance spotlight on USVs for safe use in energy fields

Published on 9 January 2023

Richard Purser, Technical Adviser – Marine talks about the use of Uncrewed Surface Vessels (USVs), to perform surveys or inspections and how that has been increasing over the last few years. With limited regulation for USVs, IMCA’s MASS Committee, drawn from members, formed a working group to create a guidance document to establish best practice for the safe and efficient use of USVs in energy fields.

The International Maritime Organization’s Maritime Safety Committee (MSC) defined four degrees of Marine Autonomous Surface Ship (MASS) vessel autonomy during MSC 100 in December 2018. It was determined that IMCA’s guidance would be specifically applicable to USVs, not for wider MASS systems. Using the IMO MSC definition our committee’s work was to produce guidance for ‘Degree three’ vessels. These are defined as ‘Remotely controlled ships without seafarers on board’ and are controlled and monitored from another location.

Safe and Efficient Use of an Uncrewed Surface Vessel (USV)’ (IMCA M 257) published earlier this year has been welcomed by members well-used to helpful guidance from IMCA. It has been produced to provide a reference document for the safe and efficient offshore operation of
USVs and the relevant support systems; and represents the initial guidance for this new, and rapidly developing, technology. This is (like all IMCA documents) a dynamic document which will be regularly updated. It is envisaged that ‘Degree four’ vessels may be included within future
revisions as the industry grows. These are defined by IMO MSC as ‘Fully autonomous ships’ on which the operating system o f t he s hip c an make decisions and determine actions by itself.

IMCA Contact

Richard Purser
Technical Adviser – Marine


IMCA M 257 is designed for use by both contractors and clients, the guidance purposely avoids subjects of minority interest. It contains guidelines and recommendations that, when combined with manufacturers’ instructions and companies’ operational procedures/ processes, allow for the maintenance of a high level of safety and efficiency across the sector. However, it does not attempt to replace the need for contractors to maintain comprehensive operations manuals, maintenance manuals, policies, and procedures.

IMCA anticipated that adoption of this document and adherence to the guidance contained within it will contribute to a safe and efficient industry that operates to common standards and that has proved to be the case with comments from users including:

“Now that M257 is out there in the industry we have something to work with, hopefully IMCA will continue to evolve the document.”

“It is good to know that credible industry experts have been actively involved with development of M257.”

“M257 is a sound base for moving forward with this very fast evolving industry.”


Our eleven-strong committee comprising representatives from Class, oil majors, vessel operators and leading pioneers developing the technologies established they wanted to keep the document user-friendly, with dedicated sections containing short paragraphs. First comes a descriptive foreword followed by an introduction to USVs; an invaluable glossary of abbreviations and acronyms (fitting for guidance concentrating on a vessel identified by its own acronym) follows; then detailed sections on USV Tasks; USV Operations; and USV Personnel. The 22-page document ends with references.

USV systems have the potential to provide a full scope of services as currently provided by crewed vessels. The section on USV tasks considers hydrographic operations; bathymetric operation; ROV/AUV operations; unmanned aerial vehicles support operations; seabed drilling operations;
environmental monitoring; and inspection and intervention operations.

The section on USV Tools is similarly comprehensive, explaining that for USVs to be effectively used for various operations, attention must be paid to the various tools, equipment and systems on board that facilitate safe and proper use.

All USVs are equipped with systems and tools, each of which fits into one of the following three areas:

  • Navigation equipment for basic operation as a vessel (which also refers the reader to the Operations section)
  • Communication equipment (with a link to the relevant section in the ‘Operations’ section)
  • Survey equipment – covered in detail in this section under three headings:
    • Vessel mounted
    • Passive deployed
    • Active employed

As industries use of USVs now encompasses a wide range of vessels, ships, and craft, each of them may exhibit varying degrees of the above; from the most basic having only simple navigation hardware, to the most complex being equipped with a range of different systems.

The fourth section,’ Environmental Considerations’, covers weather (including sea state and swell; currents; and marine life – refencing the fact that the Joint Nature Conservation Committee (JNCC) is currently unaware of any issues regarding USV operations and interfaces with marine mammals).

Next on the agenda is ‘Systems’, with an explanation that USV systems managing power and onboard auxiliary support systems requirements must demonstrate safety and require management systems that communicate to shore to monitor the potential for uncontained release of energy damaging
the environment or USV.

This leads into sub sections on ‘Operating Criteria’ including ‘safe state’; ‘Redundancy’ (covering system reliability; redundancy of systems; performance protection detection; – the three key elements of a fault tolerant design; as well as power units; internal combustion engine (ice); ice/ electric; electric;
and finally, ‘alternative fuels’, with grids focussing on ‘Carbon Fuels’; ‘Carbon Neutral Fuels’ and ‘Carbon Zero Fuels’.

‘USV Operational Activity’ follows, embracing risk assessment; operating procedures (including operational activity planning; activity specific operation guidelines (ASOGs); manuals and documentation (under which sit USV FMEA; USV Operations Manual); Communications (including Line of Sight (LoS); Over the Horizon; (OtH); Cyber Hazards; Operational Technology and IT Risks). Next comes Physical Hazards with its sections on Obstacle Avoidance/Anti Collision; and finally Remote Control Centre with short sections on Risk Assessment; Operating Procedures (both Operational Activity Planning and ASOGs); and Manuals and Documentation.

The final full section is devoted to ‘Personnel’ explaining that the aim of M 257 is to improve the safety and efficiency of USV operations, by defining minimum industry guidelines for:

  • training, qualification, and competence levels of key USV personnel;
  • developing and sustaining competence through continuous professional development (CPD) for key USV personnel

Then, looking at the objectives supporting the achievement of the aim; and at the key RCC personnel identified – RCC Commander; USV Controller; USV Operator and RCC Engineer; as well as training and qualification and knowledge requirements of RCC Personnel. A section that we readily acknowledge will be updated once further IMO and Flag State guidance is developed and issued.

Our working group has done a superb job producing M 257 and its members are well aware that change will be in the air as time goes on for it will be regularly updated keeping in step with the development of the industry.
Indeed, we encourage anyone with suggested improvements to forward these to IMCA (e-mail [email protected]) for consideration by the appropriate technical committee.

All IMCA documents are written by the industry for the industry, and we therefore welcome all constructive thoughts that aid safe and efficient operations.