Titanic Tourist Submarine Missing
06-25-2023, 02:50 PM
#51
Gets Weekends Off
Joined APC: Dec 2005
Posts: 8,914
A few feet below the waves is nothing.
Ten to twelve thousand feet below the surface is very different.
Observation windows on a shallow tourist tub are not the same at all as a vessel intended to operate with an external pressure of 6,000 psi.
Water pressure at 100' is 43 psi. At 12,500', the depth of the Titanic, pressure is about 6,000 psi.
Oceangate's Titan submersible used a window rated for a depth of 4,265'. Not 12,500'. Pressure at rated depth is approximately 1850 psi. Very different from the pressures experienced at 12,500' depth.
Titan's viewing window was 12.3 inches in diameter; the largest of any deep crewed submersible. It was an off-the shelf component not rated remotely close to the pressures anticipated on the dive. For comparison, a 12.3" diameter disc (119 square inches area) experiences a total static load of:
100': 5117 lbs
4200': 220,150 lbs
12,500': 714,000 lbs
That's not a small exceedance of the rated load for the viewing window. It's a very substantial exceedance. The Titan was assembled of components, nearly all off-the-shelf items from tourist windows to childrens video game controllers, which were not individually designed, nor rated for the anticipated loads and conditions. It would be impossible to expect them to operate any better, when put in combination with numerous other inappropriate components, in the same vessel.
Ten to twelve thousand feet below the surface is very different.
Observation windows on a shallow tourist tub are not the same at all as a vessel intended to operate with an external pressure of 6,000 psi.
Water pressure at 100' is 43 psi. At 12,500', the depth of the Titanic, pressure is about 6,000 psi.
Oceangate's Titan submersible used a window rated for a depth of 4,265'. Not 12,500'. Pressure at rated depth is approximately 1850 psi. Very different from the pressures experienced at 12,500' depth.
Titan's viewing window was 12.3 inches in diameter; the largest of any deep crewed submersible. It was an off-the shelf component not rated remotely close to the pressures anticipated on the dive. For comparison, a 12.3" diameter disc (119 square inches area) experiences a total static load of:
100': 5117 lbs
4200': 220,150 lbs
12,500': 714,000 lbs
That's not a small exceedance of the rated load for the viewing window. It's a very substantial exceedance. The Titan was assembled of components, nearly all off-the-shelf items from tourist windows to childrens video game controllers, which were not individually designed, nor rated for the anticipated loads and conditions. It would be impossible to expect them to operate any better, when put in combination with numerous other inappropriate components, in the same vessel.
Oh I agree. I’m not doubting any of what you just wrote. It’s obvious Rush didn’t take safety seriously and understand the true gravity of the situation. The Titanic’s depth is no joke.
My comment was more in general, being stuck below the water with no food, water, bathrooms, and limited oxygen supply life support system while waiting for a rescue. 100 ft is nothing and a rescue would be feasible. Still, it would not be a comfortable position. People would be panicking down there.
06-26-2023, 09:24 AM
#53
Prime Minister/Moderator
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Joined APC: Jan 2006
Position: Engines Turn Or People Swim
Posts: 40,016
A few feet below the waves is nothing.
Ten to twelve thousand feet below the surface is very different.
Observation windows on a shallow tourist tub are not the same at all as a vessel intended to operate with an external pressure of 6,000 psi.
Water pressure at 100' is 43 psi. At 12,500', the depth of the Titanic, pressure is about 6,000 psi.
Oceangate's Titan submersible used a window rated for a depth of 4,265'. Not 12,500'. Pressure at rated depth is approximately 1850 psi. Very different from the pressures experienced at 12,500' depth.
Titan's viewing window was 12.3 inches in diameter; the largest of any deep crewed submersible. It was an off-the shelf component not rated remotely close to the pressures anticipated on the dive. For comparison, a 12.3" diameter disc (119 square inches area) experiences a total static load of:
100': 5117 lbs
4200': 220,150 lbs
12,500': 714,000 lbs
That's not a small exceedance of the rated load for the viewing window. It's a very substantial exceedance. The Titan was assembled of components, nearly all off-the-shelf items from tourist windows to childrens video game controllers, which were not individually designed, nor rated for the anticipated loads and conditions. It would be impossible to expect them to operate any better, when put in combination with numerous other inappropriate components, in the same vessel.
Ten to twelve thousand feet below the surface is very different.
Observation windows on a shallow tourist tub are not the same at all as a vessel intended to operate with an external pressure of 6,000 psi.
Water pressure at 100' is 43 psi. At 12,500', the depth of the Titanic, pressure is about 6,000 psi.
Oceangate's Titan submersible used a window rated for a depth of 4,265'. Not 12,500'. Pressure at rated depth is approximately 1850 psi. Very different from the pressures experienced at 12,500' depth.
Titan's viewing window was 12.3 inches in diameter; the largest of any deep crewed submersible. It was an off-the shelf component not rated remotely close to the pressures anticipated on the dive. For comparison, a 12.3" diameter disc (119 square inches area) experiences a total static load of:
100': 5117 lbs
4200': 220,150 lbs
12,500': 714,000 lbs
That's not a small exceedance of the rated load for the viewing window. It's a very substantial exceedance. The Titan was assembled of components, nearly all off-the-shelf items from tourist windows to childrens video game controllers, which were not individually designed, nor rated for the anticipated loads and conditions. It would be impossible to expect them to operate any better, when put in combination with numerous other inappropriate components, in the same vessel.
I suspect that there's a bit more to the window story. In critical applications (including airplanes) It's common to use a 50% buffer above rated strength as the design strength.
If that was the case for the COTS window, it would never have made it to 12,500 on more than one previous occasion. Components which are intended to test at 150% are *typically* designed somewhere between 150-200%. Airplanes closer to 150%, due to the weight issue.
But since weight may not be quite as critical on a sub (additional buoyancy is much cheaper than additional lift and fuel burn on a plane), the mfg may have vastly over-designed the window for safety. My guess is that it was designed to something over 15,000', so over 300% margin over *rated* depth just to be extra safe which is of course quite understandable given the consequences of failure.
My next guess would be that OceanGate made the conscious design to operationally push closer to the design limit but I doubt they intentionally exceeded it, that would be suicidal insanity.
06-26-2023, 10:59 AM
#54
Gets Weekends Off
Joined APC: Jan 2023
Posts: 1,510
Source - boating friend, retired CO of a LA class fast Attack Sub (really neat guy BTW)
06-26-2023, 12:19 PM
#55
Gets Weekends Off
Joined APC: Jul 2013
Posts: 4,750
When a submarine collapses, it moves at about 1500 mph, that’s 2200 fps. A modern nuclear submarine’s hull radius is about 20’. So the time required for complete collapse is 20/2,200 seconds, ~ 1 millisecond.
A human brain responds instinctually to stimulus at about 25 milliseconds. Human rational response (sense + reason + react) is at best, 150 milliseconds.
The air inside a sub has a fairly high concentration of hydrocarbon vapors. When the hull collapses it behaves like a very large piston on a very large Diesel engine. The air auto-ignites and an explosion follows the initial rapid implosion. Large blobs of fat (that would be humans) incinerate and are turned into ash and dust quicker than you can blink your eye.
Sounds gruesome, but as a submariner, I always wished for a quick hull collapse Death over a lengthy one like some of the crew on the Kursk endured
A human brain responds instinctually to stimulus at about 25 milliseconds. Human rational response (sense + reason + react) is at best, 150 milliseconds.
The air inside a sub has a fairly high concentration of hydrocarbon vapors. When the hull collapses it behaves like a very large piston on a very large Diesel engine. The air auto-ignites and an explosion follows the initial rapid implosion. Large blobs of fat (that would be humans) incinerate and are turned into ash and dust quicker than you can blink your eye.
Sounds gruesome, but as a submariner, I always wished for a quick hull collapse Death over a lengthy one like some of the crew on the Kursk endured
06-26-2023, 05:58 PM
#56
Disinterested Third Party
Joined APC: Jun 2012
Posts: 6,260
I suspect that there's a bit more to the window story. In critical applications (including airplanes) It's common to use a 50% buffer above rated strength as the design strength.
If that was the case for the COTS window, it would never have made it to 12,500 on more than one previous occasion. Components which are intended to test at 150% are *typically* designed somewhere between 150-200%. Airplanes closer to 150%, due to the weight issue.
But since weight may not be quite as critical on a sub (additional buoyancy is much cheaper than additional lift and fuel burn on a plane), the mfg may have vastly over-designed the window for safety. My guess is that it was designed to something over 15,000', so over 300% margin over *rated* depth just to be extra safe which is of course quite understandable given the consequences of failure.
My next guess would be that OceanGate made the conscious design to operationally push closer to the design limit but I doubt they intentionally exceeded it, that would be suicidal insanity.
If that was the case for the COTS window, it would never have made it to 12,500 on more than one previous occasion. Components which are intended to test at 150% are *typically* designed somewhere between 150-200%. Airplanes closer to 150%, due to the weight issue.
But since weight may not be quite as critical on a sub (additional buoyancy is much cheaper than additional lift and fuel burn on a plane), the mfg may have vastly over-designed the window for safety. My guess is that it was designed to something over 15,000', so over 300% margin over *rated* depth just to be extra safe which is of course quite understandable given the consequences of failure.
My next guess would be that OceanGate made the conscious design to operationally push closer to the design limit but I doubt they intentionally exceeded it, that would be suicidal insanity.
Regardless of whether the window was capable of reaching a higher load than its rating, to utilize the window at a depth that exceeded it's rating by more than a substantial amount was ill advised at best, perhaps closer to a criminal breach of duty.
The fact that the submersible got away with exceeding it's capabilities did not alleviate it of the collision with reality on this dive. "We got away with it before" doesn't add chops, but is merely an admission of guilt.
06-26-2023, 07:11 PM
#57
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Position: Engines Turn Or People Swim
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A basic premise of engineering is that where design margins are built in or attached, one does not use that margin. If a component or structure is capable of 150% of it's design load, then one does not operate it at 149%.
Regardless of whether the window was capable of reaching a higher load than its rating, to utilize the window at a depth that exceeded it's rating by more than a substantial amount was ill advised at best, perhaps closer to a criminal breach of duty.
The fact that the submersible got away with exceeding it's capabilities did not alleviate it of the collision with reality on this dive. "We got away with it before" doesn't add chops, but is merely an admission of guilt.
Regardless of whether the window was capable of reaching a higher load than its rating, to utilize the window at a depth that exceeded it's rating by more than a substantial amount was ill advised at best, perhaps closer to a criminal breach of duty.
The fact that the submersible got away with exceeding it's capabilities did not alleviate it of the collision with reality on this dive. "We got away with it before" doesn't add chops, but is merely an admission of guilt.
06-26-2023, 10:27 PM
#58
Disinterested Third Party
Joined APC: Jun 2012
Posts: 6,260
I never speculate. It's clear what oceangate did: what the designers thought really doesn't matter. They put together a deep submersible from commercial off-the-shelf parts, and didn't even settle for their own specifications. The designer, killed in the vehicle, was an aeronautical engineer. He knew loads. He knew load paths. His website bagged about the size of the window, specifically that it was the largest in any deep submersible. A high school student could do the math.
The designer/owner/captain bragged that he reveled in "breaking the rules."
There's always that guy that wants to reinvent the wheel. He called it innovation. While it's true that innovation often comes at a cost, ignoring the basic premise of design theory, ignoring the math, ignoring basic engineering, laughing about a video game controller, decisions to bolt the occupants inside without a means of egress, lack of communications equipment, a beacon, internal controls, etc, were very serious oversights without speculating at all. That the designer chose a carbon tube two inches less in thickness not because his numbers said it was the right choice, but because the thicker tube wasn't available at the time, is quite telling.
No doubt, he didn't start the day with the intent of killing himself or others, but his was a world of shortcuts inside a very unforgiving environment.
His environment, as it turns out, did not forgive. It didn't forgive his oversights, his assumptions, his rule-breaking, or his blatant disregard of limitations, design convention, expert input, design criteria, engineering, operational inexperience, and ultimately, his chutzpah.
The designer/owner/captain bragged that he reveled in "breaking the rules."
There's always that guy that wants to reinvent the wheel. He called it innovation. While it's true that innovation often comes at a cost, ignoring the basic premise of design theory, ignoring the math, ignoring basic engineering, laughing about a video game controller, decisions to bolt the occupants inside without a means of egress, lack of communications equipment, a beacon, internal controls, etc, were very serious oversights without speculating at all. That the designer chose a carbon tube two inches less in thickness not because his numbers said it was the right choice, but because the thicker tube wasn't available at the time, is quite telling.
No doubt, he didn't start the day with the intent of killing himself or others, but his was a world of shortcuts inside a very unforgiving environment.
His environment, as it turns out, did not forgive. It didn't forgive his oversights, his assumptions, his rule-breaking, or his blatant disregard of limitations, design convention, expert input, design criteria, engineering, operational inexperience, and ultimately, his chutzpah.
06-27-2023, 08:19 AM
#59
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No doubt, he didn't start the day with the intent of killing himself or others, but his was a world of shortcuts inside a very unforgiving environment.
His environment, as it turns out, did not forgive. It didn't forgive his oversights, his assumptions, his rule-breaking, or his blatant disregard of limitations, design convention, expert input, design criteria, engineering, operational inexperience, and ultimately, his chutzpah.
06-27-2023, 11:44 AM
#60
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I wondered that as well, he of all people should have known better. Maybe he just put his faith in the engineering without getting into the weeds. Seems like Rush was quite the BS artist.
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