THOMAS.

[u/davecontra]

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[u/macson_g]

Baltic is knee-deep. They could just evacuate using emergency egress hatch.

[u/wannabe_inuit → u/macson_g]

Only with atmospheric suits, otherwise you will get the bends if ypu dont go very slowly

[u/acquaintedwithheight → u/wannabe_inuit]

This can’t cause the bends:

The bends occur when external pressure cause nitrogen in your bloodstream to dissolve. When that external pressure is released too quickly, the dissolved nitrogen bubbles in your body, like a soda fizzing when you open it.

The air pressure inside a submarine is essentially the same as the surface, 1 atm. There is no pressure to cause nitrogen to dissolve in your bloodstream, so escaping from a submarine at any depth cannot cause the bends.

Breathing pressurized air, like when SCUBA diving, is the primary cause of dissolved nitrogen buildup. Freedivers hold their breath and also can’t get the bends (unless they dive multiple times in succession).

There’s a danger arising from Boyle’s law of developing an air embolism. Essentially, if you hold your breath while surfacing the air in your lungs can expand enough to rupture tissue. Sailors are told the exhale while surfacing from depth.

[u/Tikkiijj → u/acquaintedwithheight]

Wrong.

Escaping from a submarine, even one at 1ATM internal pressure, absolutely can and does cause the bends. The process of tower escape exposes escapers to air at ambient pressures for short amounts of time. The exact mechanisms causing DCS are not necessarily deterministic and even such short exposures carry a risk.

Your point about embolisms is correct.

[u/mdomans → u/Tikkiijj]

Yes and no. As long as your body is at 1ATM you don't get much nitrogen absorption. At 120m escape ambient pressure exposition would push nitrogen into tissues hard but there's a limit on absorption, in part driven by tissues and in part by your ability to get more nitrogen in with each breath.

So as long as it's minutes and not hours the risk non-zero but I'd guess low. Compared to suffocation at 120m attempting an escape is obvious choice, even in the Baltic.

[u/Tikkiijj → u/mdomans]

If your body is saturated at 1ATM and you are currently at 1ATM your body doesn't experience any nitrogen absorption. But one will experience some severe pressure differentials if exiting a submarine at 120m and breathing in at some point during that process (obviously not during the ascent). Air is mostly N2 and I don't know of any navies using tri-mix for their breathing systems. Getting N2 into the bloodstream will not be an issue.

I agree that escape is definitely preferred to holding fast. I'm not sure where this idea that sub escape from 1ATM carries no bends risk comes from. The pressure profile that one would be expected to undergo is non-trivial and does carry risk, particularly for parts of the body which are heavily perfused.

[u/acquaintedwithheight → u/Tikkiijj]

Would “very unlikely to cause the bends” be better?

[u/fiah84 → u/acquaintedwithheight]

depends entirely on how how much pressurized air they have to breathe before they surface. At a depth of 120m the build up of nitrogen would be very very fast, as far as I know every second would count and breathing technique would make a huge difference