13 thoughts on “The Various Takes On The Submersible”
My comment at InstaPundit:
“The certification isn’t worthless, but it’s generally some third party’s opinion that certain specified standards have been met. This might seem more compelling to those who have not been involved in the development of such standards, which is often an arbitrary, and sometimes corrupt or self-interested, process.”
There’s an old saying in aviation that regulations are written in blood. A good number of aviation regulations trace their origin to lessons learned during accident investigations. The same can be said for aviation standards. I have little doubt this is true for maritime regulations and standards as well.
Yesterday, ABC News interviewed Robert Ballard about this accident. Anyone familiar with Robert Ballard’s career would admit he knows far more about this subject than any of us, and likely all of us. He stated that while the deep ocean is unforgiving, in the more than 60 years of extremely deep ocean exploration, this was the first fatal accident. The design standards developed over the years have proven their worth, but OceanGate choose to ignore them at the cost of 5 lives. The deep ocean is very unforgiving.
Chesterton wrote that before you tear down a fence, you should find out why it was built in the first place. I think the same applies to regulations and standards of design when it applies to very unforgiving environments
Good interview of James Cameron about the sub design.
“Certified”. To what standard? By whom? How? It has to take place from the original design throughout construction and deployment. There are probably only a handful of people competent to set it up and I’m betting they’re busy with their own projects. How much $? How do you justify it for a one off?
There’s a long history of experimental aircraft, often home built but they are placarded as such an prohibited from any sort of commercial use. Titan was just a piece of deck cargo until the continental shelf and nearly all laws were far astern. Anyone wanting to file a suit needs to brush up on Admiralty Law. Since the last port of call was in Canada, that’s probably where any sort of action would have to be brought.
Making deep submersible vehicles out of steel or titanium is proven technology, but the builders of such vehicles still test them rigorously in pressure chambers before launching them with people inside. Building such vehicles using composites for the pressure hull is unproven technology. It should have been subject to even more testing than a steel or titanium vehicle. Instead, it really wasn’t tested at all. Did anyone ever test a composite hull through multiple compression cycles to see if the design was free of delamination?
Experimental aircraft are prohibited from carrying passengers for hire. They aren’t allowed to carry any nonessential passengers until they’ve flown off a prescribed number of hours, typically about 40 hours for a light plane.
I disagree on the location of any lawsuits that will be filed about this accident. The suits after Bhopal were filed in California, not any jurisdiction in or near the disaster.
Presumably California had a better chance of enforcing a judgment, even though Union Carbide wasn’t (IIRC) incorporated or headquartered there. Full faith and credit, probably.
This lawsuit, when it comes, will undoubtedly follow the same principle.
Titan was a commercial passenger submarine as soon as its owner took money on the promise of a ride in it. If the contract specified going to the Titanic, that will be material to any legal examination of the disaster.
On a side note, I’d like to opine on the engineering design decision to not have a conventional hatch and conning tower.
Normally there would be an upper hatch, which is a circular through-hull opening with the hull thickened around the rim of the whole, and the extra material around the rim roughly equals the volume removed to form the hole, though not exactly. There’s a tremendous amount of engineering knowledge about how to properly do that without creating either a weak area or a stress riser.
Another possibility is to make the conning tower as a T-junction between a small pipe (the conning tower) and a large pipe (the main hull). That is also a well-understood engineering problem when made of regular metals like aluminum, steel, or titanium, or even injection-molded plastics.
But if you are set on making the hull out of unidirectional fiber-reinforced plastic that will be under tremendous stress, how do you possibly make either of those shapes? There is no wrap or weave pattern that will give you a pipe tee or a thick-rimmed hole. It would be a hand lay-up with layers of woven cloth. Even if you just laid up a cylinder and then cut out a hole, you’ve severed all those wonderful continuous strands, and done so at every angle from 0 to 90 degrees. Then you have to somehow add a thick rim that restores the strength without making a stress riser, able to smoothly handle the axial and hoop stresses. And no amount of bonding is going to do that with the same strength as the original fibers because the interface will still amount to a glued joint.
So the obvious solution is just to sidestep the problem by not having a conning tower because there’s no good way to attach one to a unidirectional carbon fiber cylinder. Instead of taking that as a reason not to build a submarine pressure hull out of carbon fiber, Rush decided to make the forward cylindrical end-cap a bolt-on “hatch”, since the end caps had to transition to metal cylinders anyway, and metal-to-metal pressure seals were well understood.
But this mean the crew couldn’t get in or out of the sub unless it was fully out of the water, and thus the little submerging platform.
One extremely difficult design problem that was the result of material selection led to the creation of additional layout and operational problems, which led to the adoption of several ad-hoc solutions. At some point early in the design process, an experienced submariner or marine architect should have waved a big red flag and said “No.”
There are not a lot of human-carrying, extreme deep-diving submarines out there. I don’t recall any of them having a conning tower. The structural issues you mentioned may be one issue, but in reality, these subs don’t need conning towers. They don’t spend time cruising on the surface. They do have a hatch for crew access built into the pressure hull, which tends to be spherical to handle the crushing pressures of the deep. In addition to using composites for their submarine, OceanGate used a cylindrical shape with hemispherical end caps. This is not a very good design for handling pressure loads of several thousand PSI.
By “conning tower” I’m referring to the hatch. Usually they put a fairing around it to help keep a wave from washing over the top and into the sub. The Trieste was a bit odd in that the hatch was at an angle and opened into an entrance trunk that had a ladder that went all the way to the conning tower on top of the sub. Or look at a diagram of Alvin, which was a spherical pressure hull with a hatch that went to the conning tower.
The idea is that any submersible can surface and the crew can get out in a reasonable sea state without the sub getting swamped and returning to the bottom. From up top they can coordinate whatever is needed before and after the dive.
Rand, out of curiosity – any uptick in book sales apropos the Titan implosion?
They’ve slung a lift strap through the big hole where the front viewport used to be. And they have the titanium rings as separate from the carbon fiber hull. Those were supposed to stay glued on.
My comment at InstaPundit:
“The certification isn’t worthless, but it’s generally some third party’s opinion that certain specified standards have been met. This might seem more compelling to those who have not been involved in the development of such standards, which is often an arbitrary, and sometimes corrupt or self-interested, process.”
There’s an old saying in aviation that regulations are written in blood. A good number of aviation regulations trace their origin to lessons learned during accident investigations. The same can be said for aviation standards. I have little doubt this is true for maritime regulations and standards as well.
Yesterday, ABC News interviewed Robert Ballard about this accident. Anyone familiar with Robert Ballard’s career would admit he knows far more about this subject than any of us, and likely all of us. He stated that while the deep ocean is unforgiving, in the more than 60 years of extremely deep ocean exploration, this was the first fatal accident. The design standards developed over the years have proven their worth, but OceanGate choose to ignore them at the cost of 5 lives. The deep ocean is very unforgiving.
https://abcnews.go.com/US/video/bob-ballard-reacts-catastrophic-implosion-titanic-submersible-100316625
Chesterton wrote that before you tear down a fence, you should find out why it was built in the first place. I think the same applies to regulations and standards of design when it applies to very unforgiving environments
Good interview of James Cameron about the sub design.
https://abcnews.go.com/US/james-cameron-compares-submersible-tragedy-titanic-sinking-im/story?id=100314415
“Certified”. To what standard? By whom? How? It has to take place from the original design throughout construction and deployment. There are probably only a handful of people competent to set it up and I’m betting they’re busy with their own projects. How much $? How do you justify it for a one off?
There’s a long history of experimental aircraft, often home built but they are placarded as such an prohibited from any sort of commercial use. Titan was just a piece of deck cargo until the continental shelf and nearly all laws were far astern. Anyone wanting to file a suit needs to brush up on Admiralty Law. Since the last port of call was in Canada, that’s probably where any sort of action would have to be brought.
Making deep submersible vehicles out of steel or titanium is proven technology, but the builders of such vehicles still test them rigorously in pressure chambers before launching them with people inside. Building such vehicles using composites for the pressure hull is unproven technology. It should have been subject to even more testing than a steel or titanium vehicle. Instead, it really wasn’t tested at all. Did anyone ever test a composite hull through multiple compression cycles to see if the design was free of delamination?
Experimental aircraft are prohibited from carrying passengers for hire. They aren’t allowed to carry any nonessential passengers until they’ve flown off a prescribed number of hours, typically about 40 hours for a light plane.
I disagree on the location of any lawsuits that will be filed about this accident. The suits after Bhopal were filed in California, not any jurisdiction in or near the disaster.
Presumably California had a better chance of enforcing a judgment, even though Union Carbide wasn’t (IIRC) incorporated or headquartered there. Full faith and credit, probably.
This lawsuit, when it comes, will undoubtedly follow the same principle.
Titan was a commercial passenger submarine as soon as its owner took money on the promise of a ride in it. If the contract specified going to the Titanic, that will be material to any legal examination of the disaster.
On a side note, I’d like to opine on the engineering design decision to not have a conventional hatch and conning tower.
Normally there would be an upper hatch, which is a circular through-hull opening with the hull thickened around the rim of the whole, and the extra material around the rim roughly equals the volume removed to form the hole, though not exactly. There’s a tremendous amount of engineering knowledge about how to properly do that without creating either a weak area or a stress riser.
Another possibility is to make the conning tower as a T-junction between a small pipe (the conning tower) and a large pipe (the main hull). That is also a well-understood engineering problem when made of regular metals like aluminum, steel, or titanium, or even injection-molded plastics.
But if you are set on making the hull out of unidirectional fiber-reinforced plastic that will be under tremendous stress, how do you possibly make either of those shapes? There is no wrap or weave pattern that will give you a pipe tee or a thick-rimmed hole. It would be a hand lay-up with layers of woven cloth. Even if you just laid up a cylinder and then cut out a hole, you’ve severed all those wonderful continuous strands, and done so at every angle from 0 to 90 degrees. Then you have to somehow add a thick rim that restores the strength without making a stress riser, able to smoothly handle the axial and hoop stresses. And no amount of bonding is going to do that with the same strength as the original fibers because the interface will still amount to a glued joint.
So the obvious solution is just to sidestep the problem by not having a conning tower because there’s no good way to attach one to a unidirectional carbon fiber cylinder. Instead of taking that as a reason not to build a submarine pressure hull out of carbon fiber, Rush decided to make the forward cylindrical end-cap a bolt-on “hatch”, since the end caps had to transition to metal cylinders anyway, and metal-to-metal pressure seals were well understood.
But this mean the crew couldn’t get in or out of the sub unless it was fully out of the water, and thus the little submerging platform.
One extremely difficult design problem that was the result of material selection led to the creation of additional layout and operational problems, which led to the adoption of several ad-hoc solutions. At some point early in the design process, an experienced submariner or marine architect should have waved a big red flag and said “No.”
There are not a lot of human-carrying, extreme deep-diving submarines out there. I don’t recall any of them having a conning tower. The structural issues you mentioned may be one issue, but in reality, these subs don’t need conning towers. They don’t spend time cruising on the surface. They do have a hatch for crew access built into the pressure hull, which tends to be spherical to handle the crushing pressures of the deep. In addition to using composites for their submarine, OceanGate used a cylindrical shape with hemispherical end caps. This is not a very good design for handling pressure loads of several thousand PSI.
By “conning tower” I’m referring to the hatch. Usually they put a fairing around it to help keep a wave from washing over the top and into the sub. The Trieste was a bit odd in that the hatch was at an angle and opened into an entrance trunk that had a ladder that went all the way to the conning tower on top of the sub. Or look at a diagram of Alvin, which was a spherical pressure hull with a hatch that went to the conning tower.
The idea is that any submersible can surface and the crew can get out in a reasonable sea state without the sub getting swamped and returning to the bottom. From up top they can coordinate whatever is needed before and after the dive.
Rand, out of curiosity – any uptick in book sales apropos the Titan implosion?
Not that I’ve noticed.
Daily Mail: Debris from doomed Titan sub – including nose with porthole for Titanic Five to view wreck – is brought ashore to Canada 10 days after ‘catastrophic implosion’ 12,500ft below Atlantic killed them all
They’ve slung a lift strap through the big hole where the front viewport used to be. And they have the titanium rings as separate from the carbon fiber hull. Those were supposed to stay glued on.
It’s like everything failed all at once!