That will lead to millions of dollars being spent with Tasmanian businesses.

"We are confident that at least 50 per cent of the refurbishment will be undertaken by Tasmanian businesses," Infrastructure Minister Rene Hidding told The Advocate yesterday.

Details of the winter refurbishments of the state-owned vessels and the lead contractor will be announced today.

One of the vessels will be refurbished while anchored in Devonport and while making its Devonport-Melbourne runs.

The other will be refurbished in Sydney, while it is in scheduled dry dock.

"This kind of injection, while related to the general building industry, features a substantial amount of work that is special to a large marine refit such as this," Mr Hidding said.

"So it's not just the building industry; Tasmania's got well developed skills in the marine fitout area due to its successful boat building industry."

Trades workers to be sourced locally will include joiners, soft furnishers, floor and carpet fitters, welders, electricians, decorators, plumbers and tilers.

The refurbishment to be done out of Devonport had previously been going to be done in Melbourne.

Mr Hidding said the government's plan for the Spirits involved boosting jobs in Tasmanian manufacturing and trades, as well as in tourism and hospitality.

Spirit passenger numbers have been growing strongly in recent months.

"The refurbishments ... are aimed at improving the passenger experience to encourage more people to travel on the Spirits, particularly the planned additional day sailings," Mr Hidding said.

"Further, given the importance of the Spirits to regional tourism courtesy of the self-drive market, growing passenger numbers will see more visitors across the Coast, as already evidenced by the pre-refurbishment spike in business, which was recently welcomed by Cradle Coast Tourism.

"In targeting an overall growth in passenger numbers, TT-Line's business plan shows fares will likely reduce by an average of 14.8 per cent over the next four years."