0909: "Worst-Case Shopping"

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InquisitiveCrow
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Re: 0909: "Worst-Case Shopping"

Postby InquisitiveCrow » Thu Jun 09, 2011 2:24 am UTC

When I shave in the morning, I try to do it symmetrically, that is, shave a little bit of the left side first, then the right, gradually working my way to the centre. I do this just in case a world-wide emergency takes place in the middle of my daily morning habits and forces me to go out as I am and do my best to save the world.
What goes on my mind is that I don't want the future generations in the post-apocalyptic world to remember me as "The Half-Beard Man".

Of course there's always the risk that history will then confuse me with Hitler. (yes, I know... Godwin's law...)

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TheSkyMovesSideways
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Re: 0909: "Worst-Case Shopping"

Postby TheSkyMovesSideways » Thu Jun 09, 2011 2:26 am UTC

elchino wrote:I don't know how it is for depths up to 50m, but I recall from my open water SCUBA training that you wouldn't actually need to find air pockets to inhale on the way up. In fact, you'd be constantly exhaling while gradually ascending, and the air in your lungs would keep expanding so you wouldn't run out.

He was talking about doing stops for "gradual decompression", in which case you definitely would need an air source during ascent.

That said, PROTIP: You wouldn't need to worry about decompression stops if escaping from a submarine at 50m depth. Since the submarine isn't pressurised, you'd have spent very little time under pressure, about would be far better just blowing straight for the surface in an attempt to minimise the very real risk of drowning rather than the tiny risk of decompression sickness. (Of course, if you'd breathed air under pressure at 50m, you'd definitely need to let that out in order to avoid bursting your lungs.
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BillD
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Re: 0909: "Worst-Case Shopping"

Postby BillD » Thu Jun 09, 2011 7:53 am UTC

The mouse-over is incorrect. You don't need to find air bubbles to do a slow decompression ascent. I have done 100 foot ascends at night that took several minutes without inhaling once. When you take a breath of compressed air at depth, you have to be sure to exhale as you ascend because the gas expands. So basically, you blow a tiny stream of bubbles as you very slowly move to the surface and your lungs just keep staying full. It's very cool. If you do it right, a 50 meter ascent can take 3-4 minutes and require little to no inhaling. In an emergency, you can totally do this without a breath. If you aren't breathing compressed air in the first place, it isn't a problem.

PoPo
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Re: 0909: "Worst-Case Shopping"

Postby PoPo » Thu Jun 09, 2011 8:52 am UTC

just because its been bothering me ...

a sub is ridged, thus the air pressure in the sub would be normal air pressure at sea level( 1 ata)
that means that at any depth you would be able to swim from the sub to the surface with out doing deco stops and you wouldn't get decompression sickness(bends)

The problem that you would have if you attempt to do this swim is that: the time it would take for the airlock to full so that you can exit the sub would be too long and you wouldn't be able to hold your breath that long and drown.
Now lets say you could hold your breath long enough to get out of the sub. You would encounter another problem: because your last breath was at 1ata and the pressure around you is now at 6ata the force of all that pressure would compress your lungs(because your body is flexible unlike the sub) so much that it would feel like your lungs are empty also the pain would be unbearable!!! thus you would probable take a gulp of water and drown.
Assuming you didn't equalize in the airlock while it was fulling up you would probable have also burst your eardrums( you would feel a sharp pain as it ruptures but the water filling your ear cannel would be soothing and the pain would aside till you get to the surface when the water runs out, then extreme pain will follow)

If you do all the right things: equalize, force yourself not to gulp water and swim for the surface you would probable be able to make it and survive like many people did in WW2
ps. a little problem you would encounter when reaching the surface is shallow water blackout. this happens to many free divers when returning from great depth

hope my knowledge about diving can help you if you are ever trapped in a sub. feel free to correct if you disagree with me

CaptainStorm
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Re: 0909: "Worst-Case Shopping"

Postby CaptainStorm » Thu Jun 09, 2011 10:25 am UTC

I can't really say I recognize the feeling...to my knowledge, the most common reason why people are willing to pay for useless extra features is because affording quality over quantity is the modern way of showing that you're rich.

FOARP
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Re: 0909: "Worst-Case Shopping"

Postby FOARP » Thu Jun 09, 2011 1:44 pm UTC

He shouldn't have worried about escaping from a submarine that's 50m below the surface. Without the ability to slowly equalize to the pressure almost 6 atm of pressure, everything in his body would instantly be squeezed. This would result in intense pain... espeically if the ear drums burst. From what my dive masters have told me, bursting an ear drum is the easiest way to drown while scuba diving because the pain is so intense. Also, at 50m, he has a good chance of experiencing nitrogen narcosis, which is the equivalent of being drunk... except you're under water and it's really dark. In all reality, trying to make an emergency swimming ascent from a submarine 50m deep is essentially suicide.


1) OK, in most sub escape scenarios, the escape tube is used and so pressurisation happens gradually. However, if it is instantaneous, then it would hurt a lot - but it is hard to think under what circumstances an instaneous application of pressure could occur in that would be survivable - basically this would require the sub's hull to be holed, since the difference in pressure would make it impossible to open the hatches.

2) Nitorgen narcosis is, like the bends, caused by pressurised gas disolving in the blood stream, so it wouldn't be a problem so long as the ascent was sufficiently rapid.

3) Escaping from a sub at 50 metres and below is regularly practised by submariners at facilities like the Royal Navy's SETT. Admittedly, under most situations in which the submarine gets into sufficient trouble for escape to be necessary, there is no time for escape, but an un-aided escape via an escape trunk is actually quite practicable so long as there is sufficent time to pull it off, even from a depth of 90 metres. With breathing equipment, it can be done at depths of more than 180 metres.

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Re: 0909: "Worst-Case Shopping"

Postby PoPo » Thu Jun 09, 2011 3:02 pm UTC

FOARP wrote:With breathing equipment, it can be done at depths of more than 180 metres.


After a depth of 66m you would need special air mix (tri mix), because a normal air mix of 21% oxygen would be toxic at a depth past 66m. The theory is that when you breath normal air past 66m your body will be paralyzed and you would stop breathing and die. This is called oxygen toxicity

I would rather try the free swim from a depth of 160m than try and do the mix calculations on the fly like that. Also as soon as you take a breath at that depth from an air source your going to have to do deco stops and get your calculations right. Too long and you run out of air, too short and you get the bends.

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Re: 0909: "Worst-Case Shopping"

Postby bmonk » Thu Jun 09, 2011 10:17 pm UTC

furgle wrote:
ijuin wrote:
furgle wrote:Vacuum cleaners:
only 2000 watts - hmm I only really want to go over each bit of carpet once, and if a sandstorm blows through my room id feel better knowing I had the extra power. better get the 3000watt machine. And I'll need the little obtuse rectangle attachment for when the fridge falls over and I want to suck up the cobwebs behind the grill without bending over.

You'll probably need to upgrade your house wiring too--3kW will strain the common 30 Ampere household circuit breaker (assuming you are on 100-120 volt power).

Australian power is 240 volts, - as for the wattage, I actually have no idea, I was just making up numbers :)


Darn! Here I just was thinking that furgle probably had his house built, and had 50 amp circuit breakers installed--just in case...
Having become a Wizard on n.p. 2183, the Yellow Piggy retroactively appointed his honorable self a Temporal Wizardly Piggy on n.p.1488, not to be effective until n.p. 2183, thereby avoiding a partial temporal paradox. Since he couldn't afford two philosophical PhDs to rule on the title.

x-whiplash
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Re: 0909: "Worst-Case Shopping"

Postby x-whiplash » Fri Jun 10, 2011 8:48 am UTC

FOARP wrote:After a depth of 66m you would need special air mix (tri mix), because a normal air mix of 21% oxygen would be toxic at a depth past 66m. The theory is that when you breath normal air past 66m your body will be paralyzed and you would stop breathing and die. This is called oxygen toxicity


Actually oxygen toxicity doesn't paralyze you.. is will cause you to spasm.. what kills you is the drowning that follows after you spit the regulator out of your mouth while spasming..
also, there is no definate limit to the depth where oxygen toxicity occurs.. using ppO2 of 1.6ata gives 66m (1.4 -> 56m), but a lot of navies allow a lot higher ppO2 than that. us navy diving manual (rev 6, 2008) allows 5min at 50ft (2.5 ata) pure O2.

feyayeruka
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Re: 0909: "Worst-Case Shopping"

Postby feyayeruka » Fri Jun 10, 2011 1:39 pm UTC

confuzedmuze wrote:I have a flashlight with a warrantee that covers everything except "shark bite, bear attack, and children under five". This has had the dual effect of preventing me from using the flashlight when diving or hiking, as well as instilling a fear of parenthood deep within my soul. I have no desire to find out why toddlers rank with grizzly bears in their small electronic-destroying capacity. :shock:

seriously? compared to toddlers, grizzly bears and sharks are wimpy in their electronic-destroying powers. not to mention ruining just about everything in your house. (though admittedly, I'm not sure why a shark would be in one's house in the first place, unless one lives in aforementioned submarine. And now that I come to think about it, if that's the case, it's probably safer to escape from a sub at 50M with a cheapo water-resistant flashlight in shark-infested waters than hang around with a toddler).

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SpringLoaded12
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Re: 0909: "Worst-Case Shopping"

Postby SpringLoaded12 » Fri Jun 10, 2011 7:30 pm UTC

My dad used to go cave-diving a lot, and he told me a lot about it. Props to Randall for understanding underwater compression and decompression, at least at a basic level.
Also if you're using a flashlight underwater at all, you should definitely go for a professional dive light. If the water resistance labels on flashlights are anything like the ones on wristwatches, then neither of those flashlights will survive 5 inches of water.

Also, I think the type of thinking that the guy picking the flashlights has going is also the sort of thinking used for things like this: http://tvtropes.org/pmwiki/pmwiki.php/Main/ptitle8px80d2wm3pd (By sheer coincidence, that article links to xkcd #722 in its first paragraph)
Last edited by SpringLoaded12 on Fri Jun 10, 2011 7:31 pm UTC, edited 1 time in total.
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PoPo
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Re: 0909: "Worst-Case Shopping"

Postby PoPo » Fri Jun 10, 2011 9:45 pm UTC

Haha back to the flash light and forgetting about all the diving laws.
I buy all my flash lights at a dive shops just so I can use them in extreme weather. But if you don't like spending money on water proof flash lights then il recommend that you rap your al cheapo flash light in a condom. I have tried it and the light worked fine at a depth of 40m.

PoPo
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Re: 0909: "Worst-Case Shopping"

Postby PoPo » Fri Jun 10, 2011 10:01 pm UTC

x-whiplash wrote: Actually there is no definate limit to the depth where oxygen toxicity occurs.. using ppO2 of 1.6ata gives 66m (1.4 -> 56m), but a lot of navies allow a lot higher ppO2 than that. us navy diving manual (rev 6, 2008) allows 5min at 50ft (2.5 ata) pure O2.

Touché... I didn't think anybody would understand that part of the laws so I just used the general law that whe use to describe oxygen toxicity and what the general excepted limits are.

I'm stil not sure what the effects are of oxygen toxicity, because I have heard of spasm and of people becoming paralyzed ( not being able to swim up to the save zone.). At the end of the day it's not oxygen toxicity that kills you its the fact that most people drown when they get it.

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Fixblor
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Re: 0909: "Worst-Case Shopping"

Postby Fixblor » Sun Jun 12, 2011 2:20 am UTC

Odds are that you've already bought what you need, so anything else is just chasing the dragon.
Goblin's Law clearly states that any marketplace full of shoppers is as equally full of scammers schemers wheelers and dealers in the archaic art of artifice.
Beware of heffalumps and woozles in particular, with their uncanny knack for nicking your snack.

The worst of the lot by far are the shady tourists, they're always "just passing through on our way to _____ ", yeah ... right.
With their blank traveller's checks and their three different brands of currencies worth of large bills.
"It's for our grandchildren", they say.
More like for the coppers. Just a nother scam to get the little guy landed in jail. Rot and bother.
Next flower shirted khaki shorts you see waddling your way, go ahead and sell them a postcard, and be sure to insist that you can't make change.
And if you can't smell your sovereign's bedsheets on the bill they hand you, make more fuss than they'd care to ever repeat, if they get that far.
They're a dirty bunch, rest assured.
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Ephemeron
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Re: 0909: "Worst-Case Shopping"

Postby Ephemeron » Sun Jun 12, 2011 10:16 am UTC

javahead wrote:I can't believe Randall missed an opportunity to mention IPv6 day!

http://www.worldipv6day.org/

I can't honestly say this improves it, but here you go.

Image

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Kingreaper
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Re: 0909: "Worst-Case Shopping"

Postby Kingreaper » Sun Jun 12, 2011 12:37 pm UTC

Ideas sleep furiously. wrote:This makes me want to buy a glow in the dark torch... You never know.

Glow in the dark torches are a godsend when camping.

"Okay, I need to find things in this tent, so first I'll grab the torch" vs. "Okay I need to find things in this tent, where the fuck is that torch?"

NotThatDork
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Re: 0909: "Worst-Case Shopping"

Postby NotThatDork » Wed Jun 15, 2011 6:58 pm UTC

InquisitiveCrow wrote:When I shave in the morning, I try to do it symmetrically, that is, shave a little bit of the left side first, then the right, gradually working my way to the centre. I do this just in case a world-wide emergency takes place in the middle of my daily morning habits and forces me to go out as I am and do my best to save the world.
What goes on my mind is that I don't want the future generations in the post-apocalyptic world to remember me as "The Half-Beard Man".

Of course there's always the risk that history will then confuse me with Hitler. (yes, I know... Godwin's law...)


Oh, no! you should leave your face half shaved half not. It's easier to ingeneer the marketing aruond it. "Who saved your life? Half beaeaeaeaeaeaeaeaeaeaerd man!"

(Birdman intonation on the "eaeaeaeaeaea")

On the serious side, I bought this (http://www.dealextreme.com/p/compass-sh ... pair-39496) just in case in the middle of a job meeting magnetics poles suddenly shift and I must guide everyone as a new leader.

Edit: What! Scientist say already happened AT LEAST once! :D


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