Harry Bates, 27, is arguably the fastest rally driver in the country but for the first time in seven years will be without his customary co-driver John McCarthy, who rang the team as they loaded their rally truck on board the Spirit of Tasmania late this week to tell them he had tested positive for COVID-19.

Stepping out of the role of team management and strapping on the helmet to take his place for the Tasmanian national title round will be 61-year-old Sydney grandmother Coral Taylor, whose storied co-driving career began long before Harry Bates was born.

"How am I feeling? A bit nervous, a bit excited but that's to be expected, I think," Taylor said, as she began to burn the midnight oil and pore over all the route charts and reconnaissance notes ahead of this weekend's round of the Australian rally championship.

"Even after all these years when I'm getting ready for an event as a co-driver, I find I'm always feeling a little like this but I think that's a good thing."

She said that this role came as a complete surprise.

"I had prepped for this event in the team manager's role and I didn't do the normal prep that I would as a co-driver," she said.

"I'm a real planner; I'm a bit OCD about all that. So this [co-driving role] threw me a bit. We were about to load the load the boat in Melbourne when John [McCarthy] rang and said he wasn't going to make it."

Just before leaving Melbourne, she had been visiting her daughter, Molly, another former Australian rally champion.

Taylor has been a fixture with the Neal Bates Motorsport team for decades but her co-driving in recent years had been restricted to occasional roles with Neal Bates in the team's rear-wheel drive Celica RA40 in the classic vehicle category of the championship.

This weekend she is stepping into a turbocharged, all-wheel drive Toyota Yaris AP4, generally regarded as one of the fastest, most-well developed rally cars in the country.

The big challenge, she admitted, was adapting to the type of pace notes - the complex shorthand-type instructions which the co-driver reads at speed to the driver to help paint a visual picture of the rally road ahead - which Harry Bates and John McCarthy had refined over years of competing together.

"There's a lot that's the same and a lot that's different," she said.

"What's different is that Harry uses a different pace note system to what Neal and I have used over years and years.

"This [Bates and McCarthy] system is more complex than what Neal and I have used. I have had some experience with the system before because I've co-driven with Molly [Taylor, her daughter] before and Molly taught Harry how do pace notes so his system is really her system, essentially."

"But I'd never felt completely comfortable with this system because I've done something different for such a long period of time."

But after a little testing and reconnaissance with Harry Bates on wet and muddy roads in the lead-up to this event, she says she is now getting to really like "and the way Harry constructs his system".

"Everyone's pace note system is individual; there's never two that are exactly the same," she said.

"But once you sit in the car with the notes, there's a really great flow and the information that is in them is really great."

Rally Launceston is a two-day sprint event of 18 special stages on gravel. Muddy roads and wintry weather are expected for the event which will be based on roads around Launceston, in the state's north.