RL news from the deep

[Keel Basa]

News from the deep:

BBC News -- "Deepest Ever" living fish filmed (http://news.bbc.co.uk/2/hi/science/nature/7655358.stm)

I know there's some scientific explanation of which I am ignorant, but it still seems strange that these little critters can happily live all the way down there, while my mighty Type IX would be crushed like a Keystone Light can.

(Note to mods/senior forum types: Do let me know if posting this sort of quasi-relevant material is frowned upon.)

[DanFraser]

They can survive down there because their innards are at the same pressure (and able to withstand said pressure) as the environment they're in. Your sub has air in it which cannot hold its pressure against water past a certain level, that's why your ears bleed before you take an eternal bath.

[Keel Basa]

And why most of those deep-sea critters die if you bring them to the surface?

[meduza]

And why most of those deep-sea critters die if you bring them to the surface? Because their inner pressure is much higher than surface pressure ,and they simply explode. :know:

[CCIP]

Indeed. That's also the difference between the deep-sea research vessels and submarines. Submarines necessarily need a lot of space (relatively speaking) at athmospheric pressure inside them for the crew quarters and working spaces, and use compressed air for regulating flotation and trim. The deep-sea vessels, meanwhile, have only a very small space for the crew which is encased in a super-thick metal shell, and use large tanks of gasoline or oil for regulating flotation. Liquids do not 'shrink' under pressure, but gases certainly do. A tank of oil submerged to that depth would be perfectly fine. A submarine hull full of air, however, will compress under pressure and past a certain point won't be able to handle it.

Of course the air's tendency to compress is not only bad for submarines, it also allows them to operate in the first place, since the entire (and very practical) ballast system is based on compressed air!

While submarine hulls have certainly come along quite far, even the hardest titanium hulls can get so thick for a submarine before they get impractical and overly heavy.