An unmanned solar vessel could provide a solution to illegal fishing and people smuggling around the world.
Designed for Australian conditions, the Bluebottle can carry up to 300 kg of equipment, such as sensors and modules, and all its electricity needs come from solar power, which is stored in lithium ion batteries. An underwater flipper means it can also be powered by waves.
The technology behind the vessel began with a 100-passenger ferry that Robert Dane, founder of Ocius, built in 2000 for use on Sydney Harbour. It went on to win the Australian Design Award of the Year in 2001, and in around 2008 he received orders for five ferries around the world.
He began thinking about how to make a smaller unmanned version that could carry a significant payload, run at reasonable speeds in Australian currents and be powered by a minimum of 10 W for 10 days without any sun.
Dane built a 10 ft prototype to show the team was on the right track, and two years ago they won a $2.8 million contract from the Commonwealth’s Defence Science and Technology Group. The team also recently won a Pacific 2017 International Maritime Expo award.
While the defence project finished in August 2017, the team has now been invited to apply for further funding under the Defence Innovation Hub. Dane spent a significant amount of time doing wave tank, model and prototype testing in order to meet the power requirement; while the team had the solar sail technology from the work on the ferry, applying that to an unmanned surface vessel was a challenge.
“The other thing that we wanted to be able to have was ‘speed of advance’ under all conditions, so if there was no sun or wind, we wanted to be able to use wave power to steer and propel the Bluebottle,” Dane said.
Firstly, it has put the flipper on the forward rudder, so the one appendage could steer the vessel and drive it forward. Secondly, the team has used a high-tech material that can be bought relatively cheaply if ordered in large quantities.
Bluebottle has 19 solar panels at 50 W each: six on each side of the sail and seven on the deck, weighing about 12 kg.
The team carried out endurance testing in March on Lake Macquarie in NSW. It was a particularly rainy period, but Dane said the team put the vessel’s sail up and all the diffused light – off the clouds and water – enabled the team to capture 250 to 300 W of power.
“Our aim is to get enough power into the batteries from the sun and use as little of it as possible for propulsion so we can roam the oceans sustainably and give about 50 W, on average, per hour to the customer if we have eight hours of sun,” Dane said.