Nearly two decades after their purchase, the Royal Canadian Navy’s fleet of Victoria-class submarines are finally in the water and "operational."

Earlier this week, HMCS Victoria gave a demonstration off the coast of B.C. The long-range hunter-killer submarine was one of four submarines purchased by the Canadian navy from the British navy in 1998.

Canada acquired the four subs second-hand from Britain for nearly $900 million. And over the years, the Canadian navy has been footing the bill of the costly repairs needed to bring the fleet up to operational standards.

The vessels were full of rust and dents, and plagued by mechanical issues. National Defence contacted CTV's Richard Madan and said that it spent $427 Million to repair them, although some analysts say the total costs are much higher.

And while three of four subs have been cleared to patrol Canadian waters, critics say they're also nearing the end of their lifespans.

"These submarines will need to be replaced within the next decade, and it is striking that there's no mention of (them) in the government's national shipbuilding procurement strategy," said Michael Byers, a professor who specializes in Canadian foreign and defence policy at the University of British Columbia, in an interview with CTV News.

Canada’s submarine program has a troubled past

Just hours into its maiden voyage in 2004, a fire aboard HMCS Chicoutimi killed Lt. Chris Saunders and injured eight others. And in 2011, HMCS Corner Brook sustained extensive damage when it hit the ocean floor.

HMCS Corner Brook is currently docked in Victoria, B.C., and the navy says it is undertaking a "schedule of deep maintenance" and won't be ready until 2017.

As HMCS Victoria cruised below the waves during its demonstration earlier this week, the crew conducted a mock-torpedo test, sending a blast of air through the cabin.

"There's no restrictions in what we're capable of doing, we have full weapons capability," said Cmdr. Alex Kooiman.

Out of the four subs, the vessel is only one that is capable of firing a torpedo, and two of them have dive restrictions.

Despite the criticism, the navy calls the launch of HMCS Victoria a critical step forward, and says that Canada's newly operational submarine fleet is important to the country's military missions around the world.

"These subs have the legs and the endurance to deploy around the globe, to position themselves to areas that are strategically important to the government of Canada and still have an effect," said Capt. James Clark.

But Byers says the launch of the fleet is nothing to celebrate.

"Canada has the longest coastline of any country in the world, and we have a navy in advanced stage of rust-out," he said.

"The navy feels (it is) necessary to celebrate the fact that three of its four submarines are actually in the water," he added.

Two of the submarines, HMCS Victoria and HMCS Chicoutimi, are set patrol waters along the B.C. coast, and a third, HMCS Windsor, will operate out of Halifax.

With a report from CTV’s Richard Madan