A wave-powered unmanned surface vessel (USV) was recently tested as a remote controlled mobile weather buoy in a joint trial carried out by MOST AV, Plymouth Marine Laboratories (PML) and the Met Office.
Plymouth Marine Laboratories (PML) helped install a suite of calibrated weather sensors provided by the UK weather agency on Iona, a 3.5m pre-production Autonaut USV, the creation of MOST Autonomous Vessels, a technology start-up based on the UK’s south coast, with the aim of testing the viability of collecting forecasting data more economically.
The Met Office’s head of marine observations, Jon Turton, said: “We are looking to assess whether an unmanned surface vehicle can be used to make reliable metocean measurements of the same quality as a moored weather buoy, and whether USVs could offer an alternative to operating moored buoys.”
Iona carried the same sensors as the Met Office use on ocean buoys to provide data for weather forecasting, including wind speed and direction, barometric pressure, air humidity and temperature, and also sea temperature.
The trial took place over four days and nights on the Western Channel Observatory run by PML where there are scientific buoys with the same sensors fitted. This will make possible a direct comparison between calibrated data from the buoys, and data gathered aboard the AutoNaut USV.
Last year Iona was out for 11 days in the same area, carrying a weather station on the mast. While the data was encouraging, it was not scientifically comparable because the sensors were not of a type endorsed by the Met Office. This time round calibrated sensors were employed with the aim of providing a validated trial.
The trial aims to find out what are the differences in data provided by a moored buoy, and a small boat circling in the same area. One difference will be the height of the sensors. On buoys they may be 3m above the water, while on the Iona they were 1.5m above the water. However AutoNaut says it would not be difficult to build larger boats with 3m masts, if the results are positive.
Moored metocean buoys are expensive to moor and maintain and sometimes break free in storms. If the USV can gather the same quality data, it will be possible to collect data for weather forecasting at reduced cost.
AutoNaut says its USV can be launched from a beach or slipway and make its own way to the buoy location. Once there it can circle on a 25m radius until told to return to base for recovery. This means that with a couple of AutoNauts to replace each other on station it will be possible to do all the maintenance ashore, even for buoys moored in the deep Atlantic. This would be another step forward in making practical use of modern autonomous capability.
“During this trial we had a good range of weather, from flat calm to 42 knot gusts,” said MOST AV director Mike Poole. “These small boats have been through storm and gale in the open Atlantic, so we are quite confident they are seaworthy.”