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My guess would be that the Oceangate ship ignores everything that it's not 'expecting' to hear. I don't really know anything about deep sea exploration, but hav

by FinnG 3y ago

My guess would be that the Oceangate ship ignores everything that it's not 'expecting' to hear. I don't really know anything about deep sea exploration, but having general purpose microphones in the water seems like a bit of an oversight to me, given the marginal cost of having them.

beowulfey 3y ago
So many things about this venture were not really considered. I am terrified that this guy was an aerospace engineer. It feels like he threw the book about engineering safety out the window. The big one is designing the sub to travel to 95% of the expected maximum depth, leaving a 5% margin of safety. I was taught to aim for a margin of safety of (I think it was) 50% back in the day. Operating so close to the safe limit for the sub is appalling. That doesn't even include all the other warning signs about the design that were brought up. The missing beacon on the sub, in case of loss of radio contact, is another standout. No consideration given for loss of power or anything. Consideration of contingency plans is so important. A minor one that is really indicative of the overall attitude is drilling screws into the carbon fiber hull, possibly exposing the hull to stress fractures from both the screws and the constant weight of holding a monitor. It's... just a silly thing that could have been avoided. I'm not saying those screws are why it failed, but if you can use an adhesive to hold your monitor in place, wouldn't you rather do that then by drilling directly into the hull keeping ~100 atm of ocean out of your face? It just makes me so sad for so many reasons. It definitely could have been avoided...
- kristjansson 3y ago
  There ... there were screws into the structual carbon fiber??
  - Spastche 3y ago
    this is the first I've heard of that but it would not surprise me one bit
  - amatecha 3y ago
    Yeah, wait, what? I also hadn't heard of that, but if true, that's seriously messed up.
  - bagels 3y ago
    Some people saw that they had affixed things to the inside of the craft. There is almost assuredly an inner liner that is not structural that these were attached to. Just like an airplane.
    - beowulfey 3y ago
      This is probably true, to be honest. I retract that part!
- cpeterso 3y ago
  > The big one is designing the sub to travel to 95% of the expected maximum depth, leaving a 5% margin of safety. Wouldn't a a 5% margin of safety mean the sub was designed to survive at 105% of the trip's expected maximum depth? 95% sounds like the opposite of a margin of safety.
- krisoft 3y ago
  > The big one is designing the sub to travel to 95% of the expected maximum depth, leaving a 5% margin of safety. Sorry, but this does not follow. I believe you are confused about the fact that the Titan was designed to go down to 4,000 meters, and the Titanic lays at 3,840 meters. And because 3,840 is so close to 4,000 you believe they had no safety margin. Do I understand you well? But the thing is when you design a submarine which can go down to 4,000m you don’t design a hull which instantly implodes at that precise depth. You add a safety margin on top of your design requirement and that is what you design for. And then using calculations, simulations and tests you convince yourself that your submersible is still safe even at that extra safety padded depth. I’m not saying that this is how they designed it. After all it seems their engineering culture was deficient in several ways. But you simply can’t conclude that they had no safety margin because they dove close to their design limit.
  - bagels 3y ago
    Safety factors are in terms of the yield stress. So, if they had a safety of factor of 3, this means that they should be able to withstand 3x the expected stress. Pressure is linearly related to depth, so it should have been designed for 12,000 meters with a reasonable safety factor like that. Of course, this doesn't take in to account sharp impacts, which, especially for carbon fiber, dramatically change the strength requirements. Some ballpark typical numbers for safety factor: spacecraft ~1.2, airplanes ~1.5, automobiles ~3
  - beowulfey 3y ago
    Yes but you also don’t want to operate so close to the safety margin. If you need to travel to 3800m, you design a sub to safely withstand 1.5x that. And then agreed that yes it should not implode right if it were to reach that depth. At least this is how I remember learning it, which I admit was a long time ago.
    - krisoft 3y ago
      > don’t want to operate so close to the safety margin. How do you know they were operating close to their safety margin?

by FinnG 3y ago

beowulfey 3y ago

So many things about this venture were not really considered. I am terrified that this guy was an aerospace engineer. It feels like he threw the book about engineering safety out the window. The big one is designing the sub to travel to 95% of the expected maximum depth, leaving a 5% margin of safety. I was taught to aim for a margin of safety of (I think it was) 50% back in the day. Operating so close to the safe limit for the sub is appalling. That doesn't even include all the other warning signs about the design that were brought up. The missing beacon on the sub, in case of loss of radio contact, is another standout. No consideration given for loss of power or anything. Consideration of contingency plans is so important. A minor one that is really indicative of the overall attitude is drilling screws into the carbon fiber hull, possibly exposing the hull to stress fractures from both the screws and the constant weight of holding a monitor. It's... just a silly thing that could have been avoided. I'm not saying those screws are why it failed, but if you can use an adhesive to hold your monitor in place, wouldn't you rather do that then by drilling directly into the hull keeping ~100 atm of ocean out of your face? It just makes me so sad for so many reasons. It definitely could have been avoided...

kristjansson 3y ago
There ... there were screws into the structual carbon fiber??
- Spastche 3y ago
  this is the first I've heard of that but it would not surprise me one bit
- amatecha 3y ago
  Yeah, wait, what? I also hadn't heard of that, but if true, that's seriously messed up.
- bagels 3y ago
  Some people saw that they had affixed things to the inside of the craft. There is almost assuredly an inner liner that is not structural that these were attached to. Just like an airplane.
  - beowulfey 3y ago
    This is probably true, to be honest. I retract that part!
cpeterso 3y ago
> The big one is designing the sub to travel to 95% of the expected maximum depth, leaving a 5% margin of safety. Wouldn't a a 5% margin of safety mean the sub was designed to survive at 105% of the trip's expected maximum depth? 95% sounds like the opposite of a margin of safety.
krisoft 3y ago
> The big one is designing the sub to travel to 95% of the expected maximum depth, leaving a 5% margin of safety. Sorry, but this does not follow. I believe you are confused about the fact that the Titan was designed to go down to 4,000 meters, and the Titanic lays at 3,840 meters. And because 3,840 is so close to 4,000 you believe they had no safety margin. Do I understand you well? But the thing is when you design a submarine which can go down to 4,000m you don’t design a hull which instantly implodes at that precise depth. You add a safety margin on top of your design requirement and that is what you design for. And then using calculations, simulations and tests you convince yourself that your submersible is still safe even at that extra safety padded depth. I’m not saying that this is how they designed it. After all it seems their engineering culture was deficient in several ways. But you simply can’t conclude that they had no safety margin because they dove close to their design limit.
- bagels 3y ago
  Safety factors are in terms of the yield stress. So, if they had a safety of factor of 3, this means that they should be able to withstand 3x the expected stress. Pressure is linearly related to depth, so it should have been designed for 12,000 meters with a reasonable safety factor like that. Of course, this doesn't take in to account sharp impacts, which, especially for carbon fiber, dramatically change the strength requirements. Some ballpark typical numbers for safety factor: spacecraft ~1.2, airplanes ~1.5, automobiles ~3
- beowulfey 3y ago
  Yes but you also don’t want to operate so close to the safety margin. If you need to travel to 3800m, you design a sub to safely withstand 1.5x that. And then agreed that yes it should not implode right if it were to reach that depth. At least this is how I remember learning it, which I admit was a long time ago.
  - krisoft 3y ago
    > don’t want to operate so close to the safety margin. How do you know they were operating close to their safety margin?