Help for Novel

[undrwater]

how about advanced CCR for the sci-fi effect? new scrubber material?

 

[gekodivebali]

Living at 200m+ long term could only be achieved in a 1 atmosphere suit and depressurised habitat. The constant pressure takes care of the use of special gases (not needed at 1bar) and decompression sickness (not achievable even on ascent). No possibility for swims either since these are very negatively buoyant, on top of not being the most flexible apparatus. Either jets or propellers could be used for horizontal and vertical displacement. As suggested, look up for Newt suits for an idea of what this would look like.
For actual breathing within the suit, do some research on rebreathers/CCRs. Basically you need to recycle the gas you are breathing in order to remove the carbon dioxide produced by your body when oxygen is metabolised. This is achieved by having the gas travel through lime. The lime absorbs the CO2 and releases heat and water in the process.
One accident that could happen is when the lime is depleted. CO2 is no more absorbed provoking hypercapnia in the subject. This can have interesting effects like hallucinations but will also provoke unconsciousness and death fairly quick...
Depending on the design of the suit and its bulk, there could be enough lime on board to last many hours. The absence of excess humidity inside the suit would also make the use of carbon dioxide sensors more easy than in actual underwater rebreathers. The "diver" could be alerted when CO2 rises, albeit this alarm could come too late in order to save her life. The scrubber or cartridge removing the CO2 could have other issues (channeling or dusting) prohibiting from doing its job properly and jeopardizing the life of the "diver" way before its expected exhaustion.
On top of this, you would need to inject some gas into the system or the subject would eventually be unable to breathe and suffocate/die as the gas is quickly depleted. I would choose pure oxygen due to the constant one bar atmosphere and in order to simplify operation when compared to using multiple mixtures. This would allow only for several hours a day into the suit since pure oxygen, even when breathed at surface pressure, will eventually result in pulmonary toxicity. When this condition develops, Expect a burning sensation in the lungs/chest, hard coughing and a feeling similar to suffocation. This could be used in a plot more realistically since symptoms take more time to develop and this condition will not be as immediately life threatening, although death could follow.
Thermal exposure should also be considered but sounds like a lesser concern with easier solutions than other issues.
More lengthy excursions at these depths could be portrayed as a fight against the clock, which would integrate well into a storyline.
The problem i see with the one atmosphere suit and your requirements is that the subject could come back to the surface without physiological harm provided that she has either an autonomous means of propulsion at her disposal or access to a line/cable linking the ocean floor to the surface...
Bon courage et bonnes recherches!

 

[matt_w]

Any environment like you describe would have to be pressurized, (depressurized?), to make it liveable. Think of 1 atm military subs. The submariners live on those things for months at some serious depths, but they do it all at normal atmospheric pressure.

Another thing you could look into are saturation divers. Those guys basically live at depth under pressure and breathe a mixture of helium and oxygen. They also venture out in suits to do their work. They don't go anywhere near as deep as you are talking about though.

For depths of 1 mile you would need a pressurized environment and pressurized suits. Both do exist though.
JIM suit - Wikipedia, the free encyclopedia

As far as a decompression accident from that kind of depth goes, you might need to get creative. 1 mile deep is freakishly out of the range of normal diving. A diver at those depths would either be in a pressurized environment or he would be using some extremely exotic diving methods that would probably involve breathing liquids.

I am not aware of any reason you can not live at the ambient pressure 1 mile down for years. It would take a long time to ascend/deco, but not ridiculously long. Eventually your tissue becomes saturated with whatever inert has your breathing. Commercial divers do saturation dives frequently. Once you reach saturation, your decompression time does not increase.

 

[261311]

I am not aware of any reason you can not live at the ambient pressure 1 mile down for years. It would take a long time to ascend/deco, but not ridiculously long. Eventually your tissue becomes saturated with whatever inert has your breathing. Commercial divers do saturation dives frequently. Once you reach saturation, your decompression time does not increase.

To my knowledge there's also little information we have on the science of living at depth for those lengths of time. If you ever needed to surface your body might react in a way a mountain climber experiences a lack of oxygen on Mt. Everest. It would probably feel like you're living in a space like vacuum because of all the additional air and gas you've now become used to having for intake. You're looking at living 150+ atmosphere's below water at that point (1mi), space is only a 1 atmosphere change.

 

[Grenouille]

Woooo this is getting specific... I'm having trouble following certain things but I'll reread everything a thousand times . For the actual consequences of the decompression accident, I kind of "need" her to become paralyzed from the waist down. I read it was possible in decompression incidents, and it makes a lot of sense to me, considering she could get brain damage in any part of her brain. I just hope a suit like the ones we're talking about doesn't take away that possibility. But if those suits do allow them to go back to the surface then I have a real problem, this just can't happen in the story. They are pretty creative down there, so if propellers or a cable were the only thing they'd need, they'd find a way. I'd lock them up inside the shelter, but that would take away a lot of the fun of having them go out and see some nasty creates try and bite their head off

 

[matt_w]

To my knowledge there's also little information we have on the science of living at depth for those lengths of time. If you ever needed to surface your body might react in a way a mountain climber experiences a lack of oxygen on Mt. Everest. It would probably feel like you're living in a space like vacuum because of all the additional air and gas you've now become used to having for intake. You're looking at living 150+ atmosphere's below water at that point (1mi), space is only a 1 atmosphere change.

I am sure there is no information on the precise effects of a mile down for extended duration. It is certainly plausible that air spaces could lose some of their elasticity over a very long duration. I know there have been dives to maybe 1 quarter of the depth that lasted for days (including decompression to the point the users could get to a chamber).

I do think living at ambient would make it much easier to go out of the capsule and explore the environment. The obvious hazard is what happens at the end.

Sea lab and other habitat projects have studied the effects at less extreme depths. I think chamber tests have only been down to about half of the 1 mile depth proposed. I don't think anyone has combined the studies (i.e. a chamber dive to 2200 feet for a year). That would take a pretty dedicated participant.

If part of the goal is that people in the habitat can routinely climb to the surface, than pressurizing at one atmosphere and using suits for excursions would allow the residents to directly ascend to the surface in a pressurized bell.

 

[Grenouille]

Hmm... I'll say it again... the goal is NOT for people to routinely climb to the surface, the goal is for all of them to stay down there for a pretty long time (years) and have no possibility to go back up. A vast majority of the people living down there have never been outside and don't intend to. And the depth is not nearly as important as their being stuck down there.

 

[Cap335]

You might want to check out a book. Ark Liberty, at least part of the book sounds like your story

 

[Grenouille]

Thanks, I just checked it out, there are some similarities and I'd be curious to see how it's written, but the context and actual plot seem pretty different (thank God). Did you actually read it, Cap335? I'm curious. As for Sphere that someone else mentioned, I already read it, quite a cool book!
Edit: I just ordered the book so no need to spoil it

 

[gekodivebali]

The reason why i don't believe ambient pressure is a possibility has to do with the question of what gases you would use and their effects on the nervous system or other parts of the human body in the long run.
So let me ask: what gases would you use at 101 bar (1km uw) of ambient pressure?

---------- Post added April 17th, 2013 at 02:59 PM ----------

Hpns and either types of O2 toxicity are not acceptable...