The federal government has decided to extend the life of one of Canada's largest scientific research vessels, the CCGS Hudson.

It means months of work replacing corroded steel on the Halifax-based ship, as the federal government delays a replacement date for the ship, first launched in 1962.

The Hudson is the main platform for Canada's marine research, a floating home base for generations of Canadian scientists.

Transport Canada forced the issue after a survey by its ship safety branch in January detailed steel corrosion above Hudson's waterline.

"Ship safety is the certifying body. Once you get to a 30 per cent wastage, you have to replace things," said Capt. Dave Martin of the Hudson.

The rust problem left the Department of Fisheries and Oceans with a dilemma — spend about $1 million to make Hudson seaworthy or idle the ship and find other vessels to carry out scientific programs.

In the end the department opted for repairs.

Two Northern science expeditions planned for Hudson this year have been moved to other vessels while repairs continue.

"They say we wont issue a certificate to sail unless repairs are made. The department has made the choice to keep Hudson going until a replacement gets here," Martin said.

The date for a replacement isn't known.

As recently as last fall Ottawa was predicting Hudson's replacement would be in service by 2014. Now DFO says the date has been pushed back to 2016.

The repairs underway at Bedford Institute of Oceanography give the department more time.

"With the repairs that are going on now and at the end of the month of August and into September, we should be good to go for another several years," Martin said.

Repairs are ahead of schedule and Hudson is set to return to sea for three science programs this fall.