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Diving into invention
Navy to use new device in tests on repairs to sub’s dented hull
By CHRIS LAMBIE Staff Reporter
Sat. Jan 12 - 5:25 AM
The navy has finally removed a dent from HMCS Victoria and experts will test the submarine’s hull next month to make sure the work was done properly.
In October 2000, Victoria was the first of Canada’s four troubled diesel-electric subs to arrive in Halifax from the United Kingdom. Nearly two years later, technicians discovered a dent in the sub that forced authorities to limit Victoria to 75 per cent of its maximum diving depth until the problem was fixed, which was supposed to happen by 2004.
"The diving depth of a submarine is very much dependent on the circularity; it’s like an egg," said John Porter, a mechanical engineer at Defence Research and Development Canada’s dockyard lab in Halifax.
"So if that egg is not perfectly spherical, then it can’t take as much pressure."
When technicians discovered Victoria’s dent, navy officials pegged the repair cost at $400,000. Military officials did not respond Friday to questions about the actual cost of the fix or why it took so long.
"That repair has just been completed and we’re hoping to use our system (called the sub mouse) to look at the circularity or the geometry of the shape of the pressure hull as a consequence of the dent that was induced and the repair work that was done to, basically, plug the hole," Mr. Porter said.
Technicians will rub the device, which looks a bit like a computer mouse, over the surface of the sub. The roller probe will use laser tracking and ultrasound to measure both the circularity and thickness of the pressure hull, producing a precise, three-dimensional computer model of the boat.
"They’re two inventions that have just been sitting around for awhile, like peanut butter and chocolate," said Rod McGregor, the engineer in charge of the work on the West Coast, where Victoria is based.
"Then suddenly, someone’s put it together and it’s like, ‘Oh wow, that’s a great idea.’ "
Defence scientists are doing a $60,000 field evaluation of the device, which they invented. It should help spot any flaw in the sub’s egg-shaped hull that could cause it to collapse under pressure.
"Maintaining a submarine’s shell in a perfectly round shape is the ideal and it’s what we would be striving for," Mr. McGregor said. "And what we want to look for over time as the submarine goes through its operational life is to check to make sure that it hasn’t gone out of circularity by too much."
The sub mouse has a second purpose.
"It also gives an ability to look at the integrity of the hull or look for any kind of development of any corrosion," said Mr. McGregor, adding that would give the navy exact numbers on how deep the subs can go.
It took 5,000 worker hours at the Pacific fleet’s maintenance facility to fix the pizza-sized dent in Victoria’s pressure hull.
"You cut a good-sized piece out and then you put a brand new piece back in and weld it into place," Mr. Porter said.
There is a risk the dent could have changed the structural integrity of the sub, he said.
"And in the submarine game, you avoid risks. Because that’s the people tube, we go through a lot of effort to make sure that safety’s not compromised."
Experts are pleased with preliminary tests on Victoria’s dent repair.
"It’s made a huge difference in improving the submarine’s diving capability over what it would have had to be restricted to had it been left with the dent," Mr. McGregor said. "So it’s been a very, very successful repair."
Canada bought the four mothballed subs from the Royal Navy in the late 1990s for almost $900 million. They were built by BAE Systems in the late 1980s and early ’90s but taken out of service when the British decided to go with an all-nuclear sub fleet.
Reactivating the subs has been a challenge for the navy, especially in the aftermath of a fatal fire aboard HMCS Chicoutimi in October 2004.
Technicians eventually plan to use the sub mouse on Chicoutimi, which is not scheduled to have its fire damage repaired until 2010 and is being used for spare parts.
"Chicoutimi did have a fair bit of corrosion. Repair work was done to her. So we need to check her circularity as well," Mr. Porter said.
"So we’ll be using this tool on her at some point in time."
People aren’t always alert to what might cause a change in a sub’s circularity, he said.
"An excursion beyond your safe diving depth could cause a minor ripple that you might not be aware of."
The sub mouse will allow defence scientists to study changes in circularity and corrosion on the subs over time.
"If we detect it right away, we can sort of nip it in the bud," Mr. McGregor said.
HMCS Windsor is undergoing repairs and upgrades in Halifax.
HMCS Corner Brook, which is also based here, is the only sub now in service.
Navy to use new device in tests on repairs to sub’s dented hull
By CHRIS LAMBIE Staff Reporter
Sat. Jan 12 - 5:25 AM
The navy has finally removed a dent from HMCS Victoria and experts will test the submarine’s hull next month to make sure the work was done properly.
In October 2000, Victoria was the first of Canada’s four troubled diesel-electric subs to arrive in Halifax from the United Kingdom. Nearly two years later, technicians discovered a dent in the sub that forced authorities to limit Victoria to 75 per cent of its maximum diving depth until the problem was fixed, which was supposed to happen by 2004.
"The diving depth of a submarine is very much dependent on the circularity; it’s like an egg," said John Porter, a mechanical engineer at Defence Research and Development Canada’s dockyard lab in Halifax.
"So if that egg is not perfectly spherical, then it can’t take as much pressure."
When technicians discovered Victoria’s dent, navy officials pegged the repair cost at $400,000. Military officials did not respond Friday to questions about the actual cost of the fix or why it took so long.
"That repair has just been completed and we’re hoping to use our system (called the sub mouse) to look at the circularity or the geometry of the shape of the pressure hull as a consequence of the dent that was induced and the repair work that was done to, basically, plug the hole," Mr. Porter said.
Technicians will rub the device, which looks a bit like a computer mouse, over the surface of the sub. The roller probe will use laser tracking and ultrasound to measure both the circularity and thickness of the pressure hull, producing a precise, three-dimensional computer model of the boat.
"They’re two inventions that have just been sitting around for awhile, like peanut butter and chocolate," said Rod McGregor, the engineer in charge of the work on the West Coast, where Victoria is based.
"Then suddenly, someone’s put it together and it’s like, ‘Oh wow, that’s a great idea.’ "
Defence scientists are doing a $60,000 field evaluation of the device, which they invented. It should help spot any flaw in the sub’s egg-shaped hull that could cause it to collapse under pressure.
"Maintaining a submarine’s shell in a perfectly round shape is the ideal and it’s what we would be striving for," Mr. McGregor said. "And what we want to look for over time as the submarine goes through its operational life is to check to make sure that it hasn’t gone out of circularity by too much."
The sub mouse has a second purpose.
"It also gives an ability to look at the integrity of the hull or look for any kind of development of any corrosion," said Mr. McGregor, adding that would give the navy exact numbers on how deep the subs can go.
It took 5,000 worker hours at the Pacific fleet’s maintenance facility to fix the pizza-sized dent in Victoria’s pressure hull.
"You cut a good-sized piece out and then you put a brand new piece back in and weld it into place," Mr. Porter said.
There is a risk the dent could have changed the structural integrity of the sub, he said.
"And in the submarine game, you avoid risks. Because that’s the people tube, we go through a lot of effort to make sure that safety’s not compromised."
Experts are pleased with preliminary tests on Victoria’s dent repair.
"It’s made a huge difference in improving the submarine’s diving capability over what it would have had to be restricted to had it been left with the dent," Mr. McGregor said. "So it’s been a very, very successful repair."
Canada bought the four mothballed subs from the Royal Navy in the late 1990s for almost $900 million. They were built by BAE Systems in the late 1980s and early ’90s but taken out of service when the British decided to go with an all-nuclear sub fleet.
Reactivating the subs has been a challenge for the navy, especially in the aftermath of a fatal fire aboard HMCS Chicoutimi in October 2004.
Technicians eventually plan to use the sub mouse on Chicoutimi, which is not scheduled to have its fire damage repaired until 2010 and is being used for spare parts.
"Chicoutimi did have a fair bit of corrosion. Repair work was done to her. So we need to check her circularity as well," Mr. Porter said.
"So we’ll be using this tool on her at some point in time."
People aren’t always alert to what might cause a change in a sub’s circularity, he said.
"An excursion beyond your safe diving depth could cause a minor ripple that you might not be aware of."
The sub mouse will allow defence scientists to study changes in circularity and corrosion on the subs over time.
"If we detect it right away, we can sort of nip it in the bud," Mr. McGregor said.
HMCS Windsor is undergoing repairs and upgrades in Halifax.
HMCS Corner Brook, which is also based here, is the only sub now in service.