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Whales, seals, and other marine mammals seem to do alright in the chill waters of the arctic seas, so the US Navy is developing a type of "artificial blubber" to allow divers to work in freezing conditions for hours on end. Sponsored by the Office of Naval Research (ONR), the collaboration between MIT and George Mason University uses an off-the-shelf wetsuit permeated with inert gases to triple a diver's resistance against the threat of hypothermia.
[...] The modification involves replacing the air trapped in the neoprene foam that provides heat insulation with heavy, inert gases, such as xenon and krypton, which make the neoprene act like fat-concentrating blubber. This is done by putting an ordinary neoprene suit into a bespoke pressure tank the size of a beer keg and pumping in the inert gases. After several hours, the gas permeates the suit, forcing the air out.
According to ONR, this makes the suit effective at 10° (50° C)[sic see note] for hours instead of minutes. The treatment isn't permanent as the gases leak out over 20 hours, but the team points out that this is much longer than the time divers spend in the water.
Why not recruit divers with more blubber?
[Note: This conversion error appeared in the original story; it should have read: 10°C (50° F). Story updated 20180907_011649 UTC --martyb]
(Score: 2) by pvanhoof on Friday September 07 2018, @06:43PM
PADI Rescue Diver (1409EW7988) here.
An example of such a neophrene drysuites can be found here [scubapro.com]. Noting that the neophrene (or whatever skin is used for the drysuit) is mostly protection against sharp objects (less dangerous) and angry fish protecting their eggs (some of them far more dangerous), and the possibility of a tight fit around your body while it's still a drysuit.
For warmth, as you point out, the air between your body and the drysuit is probably much more important. With a tight-fit neophrene drysuit, wearing a lot under the drysuit is of course difficult (it's a tight fit around your body). The fact that you can't easily wear a lot of (normal) clothes in a neophrene drysuit is why not all drysuit divers like it. It's not comfortable and can even be dangerous (not enough blood going through your vains will BTW make your body cold, too).
You can blow in more air if 40m deep the existing air gets compressed. You'll waste air from the scuba tank doing so a lot, though. So most divers try to not change too much to the air in their drysuit once the dive started. When they come back to the surface, they usually let a bit of air out of the drysuit (~ continuously while going up). Because air that has a certain volume at 40m deep will have a much later volume at 5m deep. Meaning you'd start going to the surface faster and faster (you might even fly a bit out of the water, as a blown up balloon). Going so fast from 40m to surface will probably also kill you. This is also why drysuit divers prefer not to blow air into the drysuit at 40m deep: you'll blow in compressed air. When going up to the surface, the drysuit will grow in volume a lot. You'll look like Michelin Man [wikipedia.org]. It's not easy to swim back to the boat that way, either.
Of course will most neck-seals of most drysuits let air escape through the seal if things get blown up too much.. But by the time that's happening you are going to the surface way way too fast.