Svea's new ROV went straight to the bottom

ROV stands for remotely operated vehicle: an uncrewed underwater vehicle controlled from the ship. Cameras allow the pilot to see what is happening beneath the surface and manoeuvre the vehicle in all directions.

Svea's ROV is equipped with several cameras, powerful lighting and sonar for navigation and high-quality documentation. Its manipulator arm and gripper can be used to collect samples, handle objects and deploy or retrieve equipment. Different sensors and tools can be added depending on the mission.

“We have seen a need for this capability for a long time, both in our ongoing work and among researchers who want to use Svea. Having our own ROV on board makes Svea an even more versatile platform for marine surveys and gives us greater scope to carry out ROV surveys offshore and at greater depths,” says Mattias Sköld, scientific coordinator for Svea and researcher at the Department of Aquatic Resources at SLU.

One important application is surveying marine environments that are difficult to access, such as vertical reefs with overhangs, where camera systems suspended from the ship cannot be used. Such environments are encountered, for example, in SLU's work to monitor biodiversity in marine protected areas on Sweden's west coast.

Maiden mission: recovering a lost ‘silverfish’

A ROV also comes in handy when things do not quite go according to plan.

That became clear during an expedition this summer, when the cable to Svea's MVP (Moving Vessel Profiler) broke and the instrument – known on board as the ‘silverfish’ – sank to the seabed in Hanö Bay. During normal operation, the MVP is allowed to free-fall and is then winched back up through the water column behind the ship, measuring parameters including temperature, salinity and oxygen as it goes. This time, however, it was sitting motionless at a depth of 86 metres.

“We first went down with the ROV to locate the MVP and see exactly where and how it was lying on the seabed. Once we had a good position, we made a second dive, this time with an open carabiner attached to a lifting line. Using the ROV, we hooked the carabiner onto the instrument and locked it in place. What can make this type of operation difficult is the precise manoeuvring required, particularly in poor visibility, which was the case this time. Once the lifting line was in place, we brought the ROV back on deck and were then able to recover the instrument by hauling in the line on a cable drum,” says Björn Lindell, vessel coordinator at SLU's Vessel Unit.

Collaboration on both equipment and expertise

The ROV initiative is a tangible result of collaboration within the Ship Operators Network (SON), in which seven Swedish universities and government agencies work together to develop and improve the efficiency of Sweden's research vessel fleet. Several members of the network had a need for ROV capability and worked together on the procurement.

“Research vessels and the technical equipment they require are major investments. Through SON, we can share expertise and resources and find common solutions instead of everyone trying to solve everything independently. The ROV is a good example of what we can gain by working together,” says Lasse Thorell, Head of SLU's Vessel Unit.

The ROV was supplied by Ocean Modules in Åtvidaberg, and collaboration has also been a central part of that process. Svea's requirements could not be fully met by an off-the-shelf solution, so parts of the system have been specially developed and adapted for the vessel.

Work is also currently under way on a launch and recovery system for the ROV, known as a LARS (Launch and Recovery System).

“Once the system is in place, we will be able to manoeuvre Svea safely and with high precision during ROV operations, without the risk of the cable becoming entangled in the ship's propellers. This will allow us to operate the ROV more efficiently and safely at depths of up to 500 metres,” says Björn Lindell.