[HN Gopher] NEEMO
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       NEEMO
        
       Author : throwoutway
       Score  : 36 points
       Date   : 2022-12-10 04:02 UTC (18 hours ago)
        
 (HTM) web link (en.wikipedia.org)
 (TXT) w3m dump (en.wikipedia.org)
        
       | travisporter wrote:
       | "It is deployed on the ocean floor next to deep coral reefs 62
       | feet (19 m) below the surface."
       | 
       | Divers - would a breach be fatal at this depth?
        
         | rich_sasha wrote:
         | Sort of, yes and no.
         | 
         | Divers dive with no pressure protection far, far deeper,
         | certainly as deep as 100m and beyond. If the station floods but
         | they have air to breathe, then that's fine.
         | 
         | However, they are doing saturation diving. This means their
         | bodies are full of dissolved nitrogen, which, if they were to
         | ascend to the surface over any shortish frame of time, would
         | regassify and kill them - that's "the bends". When ascending
         | grona saturation dive, it takes hours to days, depending on
         | depth, to surface.
         | 
         | So if the station floods and they each have a scuba kit, they
         | still can't surface and are potentially in trouble.
        
           | marcinzm wrote:
           | I'm wondering if due to the station being at the same
           | pressure as outside a catastrophic breach is less likely.
           | Slow flooding versus implosion.
        
             | rich_sasha wrote:
             | I was wondering that. I'm not sure.
             | 
             | If there is a hole, the things that matter are the outside
             | pressure and resistance to water flow. The latter is mostly
             | viscosity I'd think and very little to do with air pressure
             | on the inside. Whereas water pressure is 3x surface.
             | 
             | That said 19m is really not that deep, I don't think it
             | would be _dramatically_ different to a leak closer to the
             | surface. Some ships have draft of like 15m and, while
             | generally holes in hull are bad, I 'm not sure that this is
             | some kind of special design precaution. But I wouldn't
             | really know.
        
         | Gordonjcp wrote:
         | Not a diver, but recreational divers often go down to that sort
         | of depth on compressed air without any ill effects. You'd need
         | to ascend slowly and hang about at ten metres and five metres
         | for about ten minutes to let nitrogen out of your system, to
         | get back to the surface.
         | 
         | It's about three times normal atmospheric pressure so it's not
         | going to be ideal if there's an accident, but it's not like
         | going to smash you flat with pressure, it's not going to Byford
         | Dolphin you.
        
           | bonzini wrote:
           | As the other commenter explained, you absolutely need to do
           | decompression for long-enough dives. The limit at 19m might
           | be a few hours so it doesn't affect recreational diving, but
           | in this case they exceed it. So if they had scuba gear they
           | would have to stay at 19m and wait for help.
        
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       (page generated 2022-12-10 23:00 UTC)