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.
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...
> 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.
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.
> 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.
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
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.
I think I’m misinterpreting what “rated for 4000m” means. My impression is this is the maximum safe depth the sub is capable of reaching without damage. And that they are bring it regularly to 95% of that depth.
My understanding of safety margins, as I was taught, is that one should design such that you have a safety margin of 1.5x the intended use case. In other words, for 3800m expected frequent usage, it should be able to reach a depth of 5700m.
Alvin, for example, can reach a depth of 6500m.
But you’re right, we don’t know what that 4000m means, really. I’m just assuming it means safe depth without damage.
I do totally understand what you mean, but I don't think you should dismiss the idea this swiftly. This is effectively a dictatorship vs democracy argument. I tend to suspect that neither solution would provide exactly what you wanted unless you were the dictator!
If you accept that premise, the decision has to be: which system would serve the most people the best? I'm inclined to think that a team with a budget of $20M would probably get the closest.
