The cost of the already over budget Bluenose II rebuild is increasing as the project undergoes design changes to meet an upcoming certification CBC News has learned.

Communities, Culture and Heritage Minister Leonard Preyra said the final cost won't be known until the ship sea trials are completed sometime in June.

“I think we will have a much better idea of what additional costs may be involved. There definitely will be labour costs because all of these things, including adaptations and responding to the regulator, requires time,” he said.

The rebuild of Nova Scotia's sailing ambassador is being carried out under the watchful eye of the American Bureau of Shipping.

The body will certify the vessel as safe and seaworthy.

Preyra was unable to tell CBC News whether the decision to go with ABS was made before or after the rebuild contract was awarded.

The American Bureau of Shipping is requiring some design changes, including the rudder. In the past it was made of wood, but now shipping bureau is demanding it be made of steel.

“It made sense for us to go with a standard that would be acceptable to our international partners and international waters,” said Preyra.

Bluenose II was built in 1963 and weighs around 285 tonnes. (The Canadian Press)

But design changes cost money.

Already the Bluenose II is $1 million over budget and Preyra acknowledges that figure will go up.

“There will definitely be labour costs but we haven't done an assessment of that,” said the minister.

Preyra was also unable to say when the Bluenose II will sail again.

He said that will depend on the result of sea trials, but he hopes to see it in the water this summer.

Bluenose II history plagued with delays

The Bluenose II was built in 1963 and transferred to the province in 1971 for just $1, saving it from being scrapped. The Nova Scotia government invested nearly $17 million to rebuild the ship.

But the restoration project was delayed for over a year.

The Bluenose II was supposed to launch in early July 2012, putting the boat in the water just in time for the busy tourist season, but more delays meant the schooner missed the province's tall ships festivals that summer.

It launched on Sept. 29, 2012.

The original Bluenose was famous for winning every Fisherman's Cup in 18 years of competition after its launch in 1921. It was built in Lunenburg in the same shipyard as the current renovation.

The schooner is featured on the Canadian dime.