Herding AUVs

Elaine Maslin reports on the launch of a new concept in AUV deployment, which sees six vehicles deployed in conjunction with USVs.

The multi-AUV concept. Image from Swire Seabed.

It is said that the oceans are the most underexplored places on the planet, not least deep in the major subsea trenches. Now a Norwegian subsea firm is hoping to help make its discovery – and potential for development – somewhat faster.

Swire Seabed has taken delivery of a subsea vessel that is being modified to carry and deploy up to six, 6000m-rated autonomous underwater vehicles (AUVs). They will be joined by a matching fleet of unmanned surface vehicles (USVs) and two, work class remotely operated vehicles (ROVs), rated to 5000m and 6000m. The vessel, which will also have subsea lifting capability to 6000m subsea, may well be the most kitted out vessel, in terms of autonomous vehicles, in the world.

“Deploying six AUVs at one time has never been done before,” says Jan Arvid Ingulfsen, senior advisor, Survey & AUV Operations at Swire Seabed, which was founded in 2008 in Bergen and bought by Swire Pacific Offshore in 2012. “Similar work has been done in shallow water and in the military, so the technologies in a way are working today. But, quite a lot of development needed to be done to do this. We acquire six times more data than others, we shall process it [the data] much faster than others and we have an ongoing development program with software vendors.”

An unmanned surface vehicle. Image from ASV Global.

The move – putting six AUVs on one vessel – is aimed at speeding up subsea seafloor survey work.

Swire Seabed already has a six-year contract in place for its new vessel with UK-based mapping company Ocean Infinity, the owner of the AUVs and USVs. The vessel will serve as the host for the multiple AUV operations in a combined venture between Ocean Infinity, with Swire Seabed providing survey processing and project management, and SeaTrepid DeepSea of Louisiana conducting operations of the AUVs.

“To get a really good mapping product, you need high resolution,” says Arvid Pettersen, Swire Seabed’s CEO. “This is normally achieved by flying close to the seabed – using one AUV from one vessel. We will be flying up to six simultaneously – you can do large scale mapping in high resolution in a fraction of the time.” This could be for the telecommunications or oil and gas industries, where areas of the seabed need to be mapped.

Interestingly, there’s nothing revolutionarily in the technology to do this, Pettersen says, it’s what is being done with the technology that is new.

Swire’s Seabed Constructor. Image from Swire Seabed.

The vessel, recently bought from Olympic Shipping and renamed Seabed Constructor, hints at Swire Seabed’s plans for this vessel to be more than just an AUV transporter.

The vessel is 115m-long with a 23m-beam. It is now undergoing modifications for it to support its new payload – the six Hugin (Kongsberg) AUVs, and six USVs, from UK firm ASV Global – before starting its six-year contract in April.

Ingulfsen says that the AUVs will be stored onboard in six containers, which will mean they can easily be redeployed to other vessels, if required. There will also be three operations containers, which can also be redeployed. But, on the Seabed Constructor, operations will be done from a main control room in the vessel. There are also two davit systems, for launch and recovery of the USVs, plus a station for USV repair.

Each Hugin AUV has enough battery capacity for 72-hour deployments, while the USVs have double that capacity – at 140hrs – from diesel powered propulsion. Each USV can operate up to 43km from the vessel, maintaining communications, which means the six AUVs can be spread out in up to a 90km diameter around the mothership, Seabed Constructor.

During an operation, each AUV will be deployed sequentially – with up to 12 hours between each – when they’re on a joint operation, with the first deployed also the first retrieved. While this makes operations possible – maximizing battery life for each unit – and smooth, it also means data download and analysis is smoothed out, too.

While each AUV operates independently, according to pre-planned missions, they can also “talk” to each other, which can enable more precise positioning, Ingulfsen says. “We will also have a full team of data processors and geophysicists on board,” he says. “The target is to do all the processing and reporting on board,” further speeding up to process.

The ROVs onboard will be an FMC Technologies Schilling Robotics HD 5000m-rated and a high-powered 6000m-rated Kystdesign (a Norwegian subsea robotics firm), 150hp WROV, complete with its own tether management system, ordered specifically for this vessel. All the systems on the vessel will have heave compensation systems, Ingulfsen says. Wire rope currently on the vessel’s crane will be switched to fiber rope, reducing weight and easing handling requirements.

While few companies are ploughing investment into their fleets, Swire Seabed is investing. It’s an enviable position. Furthermore, the company will be able to lean on parent firm Swire Pacific Offshore’s extensive network of 20 offices globally. “It’s a really good challenge to take on and really exciting. And it’s a great time to go full speed ahead on this,” Ingulfsen says.