Out of 103 boats in the Sydney to Hobart fleet, only one will be powered by electricity.
Just six 22-kilogram batteries will power J-Bird and her crew on the 628-nautical-mile trip to Hobart's Constitution Dock.
The 52ft yacht is co-skippered by Ocean Crusaders charity founders and spouses Annika and Ian Thomson, and it will be their second crack at the bluewater classic.
"We're just trying to set the example," Ian Thomson told AAP.
"The first person who probably had an electric car here in Australia was frowned upon - 'Yeah, they'll never take off'.
"But electric engines will come into sailing. They make a lot of sense.
"We spend a lot more time sailing and enjoying the environment a whole lot better.
"There's nothing worse than a diesel sound in the middle of a yacht race, and that's what every other boat here is going to do.''
Annika Thomson said the couple's yacht reflected the times, and was a sign of progress.
"We're designing yachts, we're designing sails to be faster and faster, but we still have old fossil fuels to run it - that's not so forward-thinking," she said.
"You don't need to have that. We can have a big battery bank instead of diesel and you can run your vessel out of wind, solar or hydro-generated power."
The Thomsons' passion project began in 2020 when they saved J-Bird from rotting on a mooring in Pittwater in Sydney's north.
Her restoration required a new deck and a new engine, giving the duo an opportunity to go electric.
Two years later, the co-skippers hoisted the sails to become the first electric yacht to race the Sydney to Hobart.
J-Bird finished with line honours in the two-handed class in 2022, meaning Annika was the first woman skipper to reach home.
And they finished with 72 per cent battery power to spare.
"We had no idea because it was all really new to us. It was a trial," Ian said.
"A year later we know our boat a lot better and we have a lot more faith in what we can do and how we can do it.
"Annika has become a genius when it comes to carbon work. As we like to say, 'I cut it apart, she fixes it'."
Limiting their carbon footprint isn't just about how they get there for the Thomsons.
"The only thing we're going to leave in Hobart is paper," Annika said.
"We pre-cook all the foods at home, have it frozen and then we put it in the microwave.
"When people want to eat lunches, wraps are made fresh and wrapped up in paper.
"All drink bottles belong to the boat so they get filled, and we have cleaned up the tank so we can have fresh water out of the tub."
Outside of sailing, the Thomsons clean waterways as part of their charity work.
With their volunteers, 278 tonnes of rubbish was pulled out by hand from southeast Queensland's waterways.
The pair were most recently cleaning out Cooks River in Sydney's southeast.
