The Royal Canadian Navy's Damage Assessment and Options Analysis report for HMCS Corner Brook tells a story of a submarine suffering "extensive damage" from "tearing and dents" that left a gaping, two-metre hole in the submarine’s bow.
Seawater was "roiling" in the parts of the submarine and two of its torpedo tube doors had been torn off when it rammed the ocean floor off British Columbia two years ago.
The submarine had 60 people aboard, including some of the most experienced and senior submariners in the navy, when it rammed the rocky seafloor while cruising 45 metres below the surface.
Two sailors were slightly injured during the June 4, 2011 collision.The navy's official board of inquiry blamed Lt.-Cmdr. Paul Sutherland, the sub's captain, for the collision.
The inquiry was closed to the public and the navy only released a one-page summary of the hearing.
The navy has publicly called the accident a "fender bender" which resulted in no structural damage. But the navy's internal report tells a much different story.
The damage report obtained by CBC under Access to Information was completed three days after the grounding and contains photographs detailing the damage to the Corner Brook.
While Vice-Admiral Mark Norman, now commander of the Royal Canadian Navy, assured Canadians the damage was not as bad as it looked, the report says "structural state of sub unk." Unk is navy shorthand for unknown.
"Location of strike likely to have caused shock stress transmission within forward structure," states the navy's early damage report.
Norman had denied the damaged extended beyond what could be seen in several photographs obtained by CBC in February 2012.
The photos showed the submarine after it was hauled from the water with a hole in it the size of a ping-pong table.
"The navy has not been upfront with Canadians about the degree of damage and just how close we came to a truly serious accident. I think the Canadian navy has to come clean across the board with respect to Canada's Victoria class submarines,” said Michael Byers, a University of British Columbia defence expert who has been critical of the submarine program in the past.
The report said that there are "strong indications" of damage to the main ballast tank that may extend to the pressure hull of the submarine. The pressure hull is a thick, rolled-steel area of the submarine where sailors live and work.
"This accident came very close to claiming the lives of the entire crew,” said Byers, who co-authored a recent report on Canada's fleet of four second-hand British-built submarines.
Byers said if the pressure hull is twisted or damaged, it may be impossible for the navy to fix.
“Please bear in mind that the documents you have from the ATI request were created very soon after HMCS Corner Brook ran aground in 2011,” wrote Department of National Defence spokeswoman Tracy Poirier in an email to CBC.
“While I can say that more work has been done since then to look into what damage the submarine incurred, I have not been able to find out any details as to what was learned during these subsequent surveys.”
The navy has said it intends to repair the 2,400-tonne submarine during its scheduled refit period, which is to begin this year and run until 2016. The navy will replace the British torpedo system and other sensors and communications equipment that came with the four Victoria-class submarines Canada bought in 1998.
A similar refit process was just completed on another submarine from the class — HMCS Windsor — and it took five years instead of the planned two.
The cost of the work on the Windsor totalled $209 million and still only one of the sub's two generators is operational, limiting the distance the sub can go away from land.
The navy has not said how much more it will cost to attempt to repair the collision damage to the 70-metre-long Corner Brook.
"If it turns out not to have worked after an attempt at repairing the vessel then Canadian taxpayers will have poured close a billion dollars into a bottomless pit trying to recover this submarine," said Byers.