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#1 |
Join Date: May 2018
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I'm looking at figuring out the load of rations and supplies that would be needed for survival.
It seems that most rations may not contain water needed for survival. Meal Packs at 1 pound each appear to include water, but the more compact survival rations and higher tech food pastes don't seem to have enough mass for water. Would a full life system be able to provide enough potable water for extended survival? A battlesuited trooper or a sealed ATV is a closed system and if in a hostile environment where you can't crack seals, water is going to run out even if there is enough food pastes tubes. |
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#2 |
Join Date: May 2007
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In principle, a sealed system like a battlesuit should be able to continue more or less indefinitely on a finite water supply. Condense the moisture that's breathed and sweated into the air, filter the urine, dehydrate the feces, and you can reuse your water more or less indefinitely. In practice, none of this will actually be 100% efficient, so you'll still need to top up the supplies occasionally, but you can probably make it effective enough to keep water from being your limiting factor. (For reference, NASA was recently boasting about new technology increasing space station water recycling efficiency from 94% to 98%, albeit using equipment too bulky to carry around in a power suit; at higher tech levels, the systems will presumably be both more effective and more portable.)
EDIT: Note that food rations may potentially help make up lost water. Even if the rations are completely dehydrated, metabolism inevitably creates a certain amount of water (along with carbon dioxide) by breaking down organic molecules. In humans, the water so produced isn't nearly enough to survive on without drinking, but it could potentially be enough to make up for minor losses from a water recycling system that's not quite 100% effective.
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I predicted GURPS:Dungeon Fantasy several hours before it came out and all I got was this lousy sig. Last edited by ravenfish; 12-10-2024 at 11:42 AM. |
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#3 |
Join Date: Mar 2005
Location: Maitland, NSW, Australia
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The body uses up more water during digestion than is produced when metabolizing dry food.
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Compact Castles gives the gamer an instant portfolio of genuine, real-world castle floorplans to use in any historical, low-tech, or fantasy game setting. |
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#4 | |
Join Date: May 2007
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Yes, but most of the water "used" isn't destroyed as such, but rather excreted and so on. From the point of view of wilderness survival or ordinary nutritional budgeting, it's a loss either way; in the context we're discussing, of technological closed-system water recycling, it remains potentially available.
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I predicted GURPS:Dungeon Fantasy several hours before it came out and all I got was this lousy sig. |
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#5 |
Join Date: Aug 2014
Location: Snoopy's basement
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Any environment that has hydrogen and oxygen can provide water with the appropriate technology.
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#6 | ||
Join Date: Aug 2010
Location: The Land of Enchantment
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Some foods require more water than others. Proteins are split into amino acids via hydrolysis, but then some are recombined to make new body proteins, thus scavenging some of the water used for initial hydrolysis. But when carbohydrates are hydrolyzed most of the resulting sugars are burned to make energy, and those H2O atoms ultimately end up split up onto other molecules, much of them excreted as waste. That's why you get thirsty after a big carb load- there is a net loss of water. Yes, glycogenesis and such processes can release water (as can producing fat) but then the glycogen needs to be hydrated with quite a lot of water to be stored. That's why marathon runners end up a few pounds lighter at the end of the race- not from the glucose used, but rather by releasing (and excreting) the water in their livers that's used to store glycogen. This stuff all ties in together and gets complex. Here is the metabolic chart that you more or less memorize in advanced biochemistry classes. But the bottom line is that digestion does not produce water- it consumes it.
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I'd need to get a grant and go shoot a thousand goats to figure it out. Last edited by acrosome; 12-21-2024 at 01:47 PM. |
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#7 | |
Join Date: May 2007
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I predicted GURPS:Dungeon Fantasy several hours before it came out and all I got was this lousy sig. |
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#8 | |
Join Date: Jun 2013
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Let's say you start with a 10-chain starch. You use up 10 molecules of water and produce 10 molecules of glucose. Those then become 20 molecules of water and 20 molecules of pyruvate. The pyruvates consume 60 molecules of water and produce 20 via the citric acid cycle. So you wind up using a total of 70 molecules of water and get 40 back, for a net loss of 30. There's a reason bread makes you thirsty when you eat it. Actually, my experience is that just about anything other than juicy fruits (which provide quite a good deal of water on their own) makes me thirsty when I eat it.
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GURPS Overhaul |
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#9 | |
Join Date: May 2007
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I strongly suspect that the primary cause of thirst on eating is the fact that the physical aspect of digestion requires lots of water to be secreted (in saliva, gut fluids, and so on) to get the food into a form from which the nutrients can be absorbed (along with the fact that some of the more interesting products of breaking down organic molecules will need to be removed from the body by urination, with the inevitable use of water that this entails).
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I predicted GURPS:Dungeon Fantasy several hours before it came out and all I got was this lousy sig. |
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#10 | |
Join Date: Feb 2005
Location: Berkeley, CA
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Water recycling is fairly straightforward, but it's also not too difficult to get it safely through a seal if environmental water exists at all. |
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