VICTORIA - Canada's top military officer defended the battered image of the military's submarine fleet Monday during undersea training exercises on board HMCS Victoria off Vancouver Island.

Gen. Walt Natynczyk, chief of the defence staff, said submarines are vital and necessary parts of the military machine with their ability to protect sovereignty in a stealth-like machine that packs formidable firepower.

Natynczyk and Vice-Admiral Paul Maddison, chief of Canada's Navy, spent about five hours on board the Victoria-class submarine as the vessel conducted dive sea trials about 12 kilometres south of Victoria.

The crew of about 50 men and women are participating in 25 days of exercises that will include about two weeks at sea, where the crew will conduct round-the-clock tests that include fire drills, tracking exercises and battle preparations.

Natynczyk, who mingled with submariners throughout the voyage, taking control of the vessel's steering wheel at one point, spoke candidly about the pounding the submarine program's image has taken.

But he said Canadians should understand that things are getting better after an inactive period where he said a state of atrophy developed.

The HMCS Corner Brook sustained damage last June after it hit bottom in Nootka Sound off the West Coast of Vancouver Island.

A military board of inquiry found was accident was caused by human error last year, but military officials are downplaying recent photos of vessel's damage, comparing the gash in the vessel's hull to a ding on a car bumper.

The 70-metre long Victoria recently underwent a three-year period of refits to repair damage that included dents that prevented the vessel from deep-sea diving.

Natynczyk said some of the criticisms of the submarine program are well-founded because there were long periods where the vessels were in repair and crews were not able to practise properly.

"But as the commander of the Navy says, we're at the end of the beginning," he said.

The federal government bought four submarines from Britain in 1998 for $750 million. They were renamed Victoria-class subs and named four Canadian cities, Chicoutimi, Windsor, Corner Brook and Victoria.

Repairs on the vessels since their purchase have reported cost hundreds of millions of dollars.

HMCS Chicoutimi caught fire on its maiden voyage to Canada in October 2004, was travelling to Canada in October 2004 when it caught fire. One sailor died and numerous others suffered smoke inhalation.

Natynczyk said the submarines need the opportunity to show their value to Canada's military forces.

"From a sovereignty standpoint, from a stealth standpoint and from a strike standpoint, this is one of the most potent capabilities that the Canadian forces has," he said. "The problem is not a lot of people understand that. When this boat is underwater nobody knows where it is, and that's powerful."

Natynczyk said he can't worry about the political pressures the federal government is facing over the future of the submarines.

"For me to achieve the missions the country has asked of me, to exercise sovereignty, to work as a reliable partner with our allies and to project leadership abroad and to enable our people to be successful, we need submarines," he said.

The sailors on board Victoria, who expect to spend much of the next two weeks underwater, said the support and presence of the chief of defence staff was uplifting.

"The crew are jazzed to have the chief of defence staff and the admiral on board," said Lt.-Cdmr. Christopher Holland. "It's great for the team to be able to show off their skills and show what they've been able to accomplish over this past year."