USV Maxlimer Maps Pacific Hunga-Tonga Underwater Volcano in a Survey Mission

  • August 21, 2022

The British company SEA-KIT International’s developed Robot Boat, aka Uncrewed Surface Vessel (USV) Maxlimer has returned from an initial survey mission inside the caldera of the Hunga-Tonga Hunga-Ha’apai (HT–HH) volcano carrying a plethora of data and imagery to fill important gaps in current understanding and knowledge of the seamount and water above it.

For the ongoing second phase of the NIWA/Nippon Foundation Tonga Eruption Seabed Mapping Project – TESMaP, funded by The Nippon Foundation, USV Maxlimer is equipped with a Multibeam Echo Sounder (MBES) to acoustically measure depth and state of the seabed. Importantly, the vessel also has new winch capability for deployment of multiple sensors down to 300 metres to obtain direct water column measurements.

The 12m-long Maxlimer may be in Tonga, but it is being remotely controlled from 16,000km away in the small coastal village of Tollesbury in Essex. Everything is done over satellite link.

In a dark control room in Sea-Kit’s HQ in the UK, several large screens display live feed images from the 10 cameras on board Maxlimer. Operators, who work in shifts around the clock, watch on as real-time data gets beamed in from the South Pacific.

On this survey mission, clear signs of continuing volcanic activity were seen inside the crater, with high particle concentrations in the water that are consistent with earlier observations of ash in the water column. The water in the caldera was also found to be homogenous between 150 and 300 metres depth, suggesting strong mixing inside the caldera. The previously observed oxygen minimum was not as distinct.

Ashley Skett, director of operations at Sea-Kit, told BBC Radio 4’s Inside Science programme that the operators can even communicate via radio with other vessels in the area, so much so that other boats wouldn’t know that nobody was on board Maxlimer.

“The boat has been designed from the ground up to be remotely controlled and remotely operated. So every switch, every function on the boat, every light, we can control from here.”

Robotic, remotely controlled boats are likely to be the future of maritime operations. When surveying a dangerous area such as the active HTHH volcano, remote control ensures no crew are put in harm’s way.

There are also environmental benefits to USVs. As there is no onboard crew to support, the vessel can be much smaller, leading to reduced carbon dioxide emissions.

“We use 5% of the fuel that an equivalent manned vessel doing the same job that we’re doing now would use,” Ashley said.

The boat is gradually building up a bathymetric (depth) map of the volcano’s opening, or caldera

In January the eruption of the volcano caused extensive damage far beyond Tonga, triggering a massive tsunami that spread across the Pacific Ocean. The atmospheric shockwave caused by the eruption was felt as far away as the UK.

USV Maxlimer is on a short break due to rough weather in the region. Once conditions improve, the robot-boat is expected to return back to the underwater volcano for filling in the remaining gaps in the caldera’s map.

The collected data could help understand the eruption’s huge and violent impact, as well as help predict the nature of future eruptions.

Credit to: BBC