Ocean Infinity has upped the ante on its robotic vessel fleet, booking its largest shore-controlled boats ever from shipbuilder Vard.

The US marine robotics company, which uses its vessels for ocean and seabed mapping, said it struck a contract for eight of the 78-metre multipurpose vessels.

The boats will ultimately be able to operate unmanned, though a skeleton crew is optional.

"The impact and the scale of this robotic fleet will spark the biggest transformation the maritime industry has seen since sail gave way to steam," said Oliver Plunkett, Ocean Infinity's chief executive.

"With our new fleet we will be able to provide sustainable services to all corners of the industry from offshore energy, to logistics and transport."

The vessels will join Austin, Texas-based Ocean Infinity's planned Armada fleet of carbon-neutral ships.

Ocean Infinity said they will be able to run on ammonia and other alternative fuels. Vard, which is controlled by Italy's Fincantieri, said the ships will have an an "ultra-low carbon footprint".

"We, as an industry, have to embrace the need to be carbon neutral. It is not, however, something that will be achieved overnight or indeed in a year, rather it will be a journey over time requiring bold leaps forward and challenge to all convention," said Plunket. "This move is a giant step forward towards that goal."

Nine vessels are already slated to hit the water in early 2021 for Ocean Infinity's Armada fleet. But the first-phase vessels are smaller, with several at 21 metres and the rest at 36 metres in length overall.

Mid-2022 delivery

The larger, newly ordered vessels are scheduled to be delivered between mid-2022 and the end of 2023. They will be constructed at the Vard Vung Tau shipyard in Vietnam. The price tag for the order was not disclosed.

Vard chief executive Alberto Maestrini said the Norwegian shipbuilding company is working closely with regulators to introduce green fuels like ammonia.

Ocean Infinity's Armada fleet of robotic vessels will be operational next year. Photo: Ocean Infinity

Design and engineering is taking place at Vard Design, and development of onboard control systems is underway at Vard Electro in Alesund, Norway.

The ships will also feature dynamic-positioning-two capabilities, "vast deck space", and twin moonpools that allow deployment of remote-operated vehicles and autonomous underwater vehicles, Maestrini said.

"Together we take a huge leap forward into a new segment of the maritime industry by developing and providing vessels prepared for the future," Maestrini said.

Ove Bjorneset, Vard's vice-president of research and innovation, said the VARD 9 60 vessels will have "highly-optimised hull forms, propellers and engine arrangements".

"The vessels are inherently developed for safe and secure prolonged missions with a redundant mindset like split engine and propulsion rooms, redundant cooling systems, sensor systems, automation and power management systems, navigation and communication systems," he said.

Founded in 2017, Ocean Infinity operates in the energy, renewables and subsea cable sectors, and it carries out work for governments and navies.

Its Infinity fleet is made up of 14 autonomous underwater vessels that operate together to capture large amounts of ocean and seabed data quickly.