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Comment by mpreda | Hacker News Reader

I wonder why the submersible was not equipped with redundant "self surface" systems. I imagine the overall density of this submersible to be close to that of water. Such that dropping some amount of ballast (like the metallic rails underneath) may lighten it enough to self-surface. In addition, some emergency "baloons" may be fitted, inflatable in an emergency by CO2 capsules to resurface. And an emergency system to open the sub (e.g. by blowing up a hole somewhere convenient) could be added as well to allow exit once at surface.

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It is. It has electromagnetic drop weights that are meant to detach on power failure.

Thing is, when it’s out of the water and the power is off, there’s going to be a mechanism, bolts or dogs or zip ties or whatever, to keep them on - and someone has to remember to detach those as part of the launch.

It'll be another appaling surprise if they didnt have a panel or box along a checklist, either inside the sub or next to a control panel to store and verify all those safety pins and locks.

It wouldn’t be the first time they’ve had a mundane mistake that has potential severe ramifications - like fitting a thruster backwards. Doesn’t inspire confidence.

I mean - I can think of so many examples in my life where I’ve seen some safety measure Macgyvered out of existence because it was inconvenient, and familiarity breeds complacency. I’m reminded of some really gnarly ski lift accidents where emergency brakes were disabled because they tripped inappropriately due to improper maintenance, and flights which have taken off with their pitot tubes still covered, and inertial measurement units fitted upside down in rockets, and on and on it goes.

Oh, or watertight compartments which didn’t go all the way up the hull because it was expensive and inconvenient. Oh, the irony.

The Risks Digest. Highly recommended.

https://catless.ncl.ac.uk/risks/

Endless food for thought.

Here is a nice article:

>The maker of the lost Titan submersible previously complained about strict passenger-vessel regulations, saying the industry was 'obscenely safe'

https://www.insider.com/titan-submarine-ceo-complained-about...

In acynical way, it is fitting. Titanic was not the worst marine desaster in term of life lost. But since it was the rich and the celebrities who died on tha Titanic, well, it was enough to tackle safety.

When safety issues cause the loss of life, but don't for some reason grab the headlines in specific ways, nobody cares.

Not sure whether it’s applicable here. But when learning scuba diving, we were taught (or rather reminded of, from middle school physics) that a balloon would become bigger as one gets closer to the surface. A balloon 90m under water will be 10X the size when it’s at surface. Therefore, using a balloon for emergency surfacing will lead to a monotonically increasing acceleration rate (which means you’ll going be too fast), or probably bursting the balloon half way through.

Indeed the pressure is huge down there, and this may represent a challange in inflating the ballon in the first place. Looking up the numbers, it seems the pressure at the Titanic is about 400bar, while the pressure of a CO2 cartdrige is about 800bar, so that works.

About the baloon becoming larger as it surfaces, a pressure release valve that vents the baloon based on the pressure differential with the exterior (water) may do the trick.

Use a bell shaped contraption instead of a balloon.

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