Eight Days, No One Aboard: What Autonomous Endurance Means for the Inspection Economy

Week 25  |  May 2026

Two vessels. Two countries. The same month.

MARTAC announced on 5 May that its T38 Devil Ray, owned and operated by the US Navy's Point Mugu Sea Range (Point Mugu), had completed a 192-hour autonomous mission 400 nautical miles off the California coast. Eight days, no crew, no chase boats with conditions up to sea state 5 at the peak, and averaging Sea State 3 across the mission. Single-engine operations deliberately sustained for two days at maximum range, not as a failure mode but as a demonstration of operational flexibility. COLREGS-compliant collision avoidance handled throughout.

Then, on Monday 18 May, Maritime Robotics' Mariner X departed its headquarters at Brattørkaia in Trondheim and set out on a 500 nm unmanned voyage down the Norwegian coast, without a human aboard. The first leg alone, Trondheim to Mongstad north of Bergen, covered over 300 nautical miles. A live SeaSight camera feed tracked the entire transit publicly. The hashtags Maritime Robotics used to describe the mission are instructive: #inspeksjon (inspection). #offshore. #havromsteknologi (ocean technology). 

They weren't talking about warships.

The T38's 192-hour mission wasn’t a vendor demonstration. The customer is the Naval Air Warfare Center Weapons Division's Future Capabilities Office, a test-and-evaluation directorate - not a procurement program office. Point Mugu needed an instrumentation platform capable of operating in challenging maritime environments where fixed-position assets can't go. The T38 filled that role for eight days without anyone aboard.

That context matters. This is a US Navy mission, not a pitch deck. The operational parameters, 400 nm offshore, up to sea state 5, deliberate single-engine loiter, continuous COLREGS compliance, weren't chosen to impress a trade show audience. They were chosen because that's what the mission required.

The platform itself is worth understanding. The T38 is a 38-foot (11.6 metre) carbon-fibre catamaran. It has a maximum payload of 4,000 lb, and a burst capability north of 50 knots. Endurance-optimised, it's rated for over 2,400 nautical miles of operational range. It is a defence-fielded platform. Task Force 59 in Bahrain has operated variants, but the operational envelope it demonstrated on 5 May maps directly onto something the offshore energy sector has been asking about for years.

The Mariner X is a different animal. Nine metres (29.5-foot) of high-density polyethylene hull, described by Maritime Robotics as nearly unsinkable, with a rated range of over 2,500 nautical miles at survey speed and endurance of up to 25 days. It carries one tonne of deck payload capacity, two moonpool elevators, and Maritime Robotics' full autonomy stack: the Autonomous Navigation System, SeaControl, and SeaSight live camera feed. This is the same technology stack Ørsted contracted for its offshore metocean USV fleet, on a hull that is designed in line with DNV's CG-0264 autonomous-ship guideline. 

Designed in collaboration with Ulstein Design, Maritime Robotics called the Mariner X all-Norwegian technology, built to make complex and dangerous operations far out at sea safer and more efficient. 

The Trondheim-to-Mongstad transit is the most significant thing about the Mariner’s most recent journey. Mongstad is not chosen arbitrarily. It's home to Equinor's refinery and the Technology Centre Mongstad, one of the world's largest carbon capture test facilities. The destination is an active offshore energy hub. The route runs along one of Europe's most demanding coastlines. Norway has a seven-person autonomous maritime technology team at the NMA that partners with industry rather than waiting for international consensus, and from 1 January 2026 the authority began formally issuing Remote Operations Centre licences for shore-based maritime personnel.

Maritime Robotics already operates the world's first approved commercial autonomous freight route. Trondheim to Vanvikan, approved by Kystverket and Sjofartsdirektoratet in March 2023. The Mongstad transit is a step-change in scale. And the company tagged it explicitly as an inspection and offshore mission.

On 22 May, the final day of MSC 111 in London, the IMO adopted the International Code of Safety for Maritime Autonomous Surface Ships. The MASS Code (the Code). Non-mandatory for now, taking effect 1 July 2026. Mandatory entry into force still targeted for 1 January 2032.

IMO Secretary-General Arsenio Dominguez called this a landmark achievement that positions IMO at the forefront of regulating emerging technologies. The Code covers design approval, remote operations, connectivity, fire safety, cybersecurity, and search and rescue. It requires Remote Operations Centres. It maintains that a master retains overall responsibility for the vessel at all times, even if not aboard.

While the Code applies to cargo ships under SOLAS Chapter 1, meaning it doesn't directly govern the T38 or the Mariner X, that's not the point. The Code is the international goal-based standard that every national regulator, NMA, USCG, UK MCA, will now harmonise toward. It's the framework that makes insurability possible. It's the document that turns 'we're still figuring out liability' into 'here's the chapter and verse.'

Three things happened this month: a US Navy platform proved eight-day autonomous endurance at 400 nm offshore. A Norwegian commercial platform transited 300 nm of active coastline without crew. And the IMO gave the world's maritime regulators a common language to catch up with both.

There is a reasonable challenge to all of this and it goes something like this: autonomous USVs of the T38 or Mariner X class are not Service Operations Vessels. They can't transfer technicians to a turbine transition piece via a motion-compensated gangway. They can't carry intervention teams. They don't do heavy lifts. They can't extract an injured worker from a platform in sea state 6. For offshore wind O&M, which is fundamentally about moving people to assets, that's the ballgame. A 38-foot carbon-fibre catamaran, however impressive its endurance numbers, is not replacing an 87-metre walk-to-work vessel on a 30-year charter.

That's a fair point. And it's worth taking seriously, because not every claim made for autonomous systems in this space is well-grounded.

But it is also answering the wrong question.

The SOV's job is not one job. It is several jobs bundled into one large, expensive platform because historically that was the only way to do them. Crew transfer to turbines: yes, that requires a crewed vessel with a motion-compensated gangway. No autonomous USV can replicate it today. But routine inspection, blade condition assessment, subsea cable route survey, metocean data collection, platform approach monitoring; these do not require a crew aboard. Neither does persistent environmental monitoring, bathymetric mapping, or the kind of continuous asset surveillance that currently requires deploying a vessel and its crew to wait.

Research from the ORCA Hub, funded by EPSRC, puts a number on what's at stake: 80% of the cost of offshore O&M is typically attributed to transporting engineers to remote sites for asset inspection. Not the inspection itself. The transport. The vessel. The crew. The waiting.

Autonomous USVs don't replace the SOV's crew-transfer function. They eliminate a significant portion of what the SOV is doing when it isn't transferring crew.

The offshore SOV and CSOV market is heading into a period of oversupply. Intelatus Global Partners projects the global fleet growing from over 60 vessels in 2024 to at least 123 by 2028. The European newbuild pipeline through 2028 requires an estimated 3,225 additional senior and junior crew positions, a recruitment bottleneck that operators are already flagging in their annual reports.

Offshore wind O&M represents roughly 25 to 35% of total lifecycle cost for a fixed-bottom farm. Higher for floating. That cost structure is under active pressure from developers whose projects are already running over budget. The question procurement teams are quietly asking is not whether autonomous inspection can replace the SOV, it's which SOV missions can be separated out and handed to a platform that costs a fraction of the day rate, needs no crew, and can stay on station for 25 days.

Ørsted has already answered that question for metocean campaigns. Its Hugin USV fleet, built by Tuco Marine with Maritime Robotics' autonomous navigation system, operates continuously in North Sea conditions. Documented in waves up to 9 metres. Argeo's Mariner X variant, branded Argus, is operational for offshore energy mapping in 2 to 200 m water depths. Jan De Nul ordered a Maritime Robotics USV for autonomous offshore surveys in 2022. Ashtead Technology rents the same platform class for maritime data acquisition.

This is not theoretical. It is already happening. What the T38 mission and the Mariner X transit demonstrate is that the operational envelope - endurance, range, sea state tolerance, COLREGS compliance, is no longer the limiting factor.

The binding constraint now is not capability. It is regulation, insurance, and institutional doctrine.

The USCG has limited statutory authority to reduce crew requirements on commercial vessels in US waters. The agency has told the GAO it cannot waive minimum crew requirements outside a single narrow pilot program. That is a legislative problem, not a technology problem. Norway solved the equivalent problem for its domestic waters through the NMA's permitting framework and the Kystverket route approval process. The IMO MASS Code, adopted this week, gives every other jurisdiction a starting point.

Insurance is thin. There is no publicly available actuarial framework for autonomous commercial inspection USVs operating in offshore energy environments. The NMA's approach, clarifying responsibility as a prerequisite for insurability, is the right model, but it requires regulators willing to engage before they have all the answers. Most aren't there yet.

And then there is institutional doctrine. The offshore energy sector's procurement frameworks were built around the assumption that inspection requires a vessel and a crew. Changing that assumption, even where the technology and the economics both support it, requires someone inside a major operator to write a procurement that looks different from every procurement that came before it. That is harder than it sounds. Ørsted did it for metocean. The question is who does it next, and for what mission category.

The T38's 192 hours offshore and the Mariner X's 300 nautical miles up the Norwegian coast didn't change the physics. They confirmed what the physics already allowed. The gap between what autonomous USVs can demonstrably do and what they are actually contracted to do is now an institutional gap, not a technology gap.

We turn to Australia's mine warfare capability gap, and why autonomous MCM is the clearest use case for integrated UUV/USV deployment that almost nobody in Canberra is talking about.

Since you have been, thanks for reading.

Cheers,

Mick

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