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Old 01-20-2023, 10:25 AM   #11
Pursuivant
 
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

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Question - what would be the "rough water" penalty if you're simply swimming underwater, maybe around 20-40 ft deep, in order to do something or get somewhere, as opposed to trying to stay on the surface to be rescued? From submarine experiences wave action stops pretty quickly a depth increases, so you might have calmer water but also be totally immersed.
Good questions.

It seems that tests and rescue experience with human subjects assumes that they're submerged except for their heads. Rough water forces people to spend more energy keeping their heads above water, means more water is moving around them (hence faster cooling due to faster heat exchange), and gets their heads wet. All that means faster cooling.

If you're in deep, still cold water, doing nothing and maintaining a fetal position to hold in warmth, I'd assume that there would be no change in modifiers as long as you could hold your breath or breathe normally. If you're expending energy by swimming, you might have a more severe penalty.

If there's some sort of strong underwater current (e.g, the bottom of a fast-flowing river) you'd still have the penalties for rough water due to extra energy needed for "station keeping" and increased heat exchange.
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Old 01-20-2023, 06:32 PM   #12
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

Perhaps no additonal effect was intented and you can only fail and lose 1 fp, that's how I do it, anyway.
I suppose a critical failure could warrant a reroll with the thermal shock rules, if you want to be extra dangerous.
Maybe with the margin of failure divided by two or something.
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Old 01-20-2023, 11:23 PM   #13
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

The mechanics of dying of cold in atmosphere vs. water vs. thermally conductive liquids are identical, it's just the rate at which heat gets transferred away from the body and effectiveness of insulating materials that changes.

Realistic and comprehensive Cold Injury rules would index ambient temperature, windspeed/current speed, thermal conductivity of the surrounding medium and a few other things to determine time between required HT rolls, HT penalties, and risk of Immersion Shock.

For example, if you're exposed to 250 mph winds and the ambient temperature is -60 *F (e.g., riding in an exposed portion of an airplane flying in the lower stratosphere), you're going to die of hypothermia a lot faster, and take a lot more frostbite damage, than if you're in a 30 mph wind in 55 *F weather. If you're suddenly thrown into a cryogenic chamber filled with -200 *F (or otherwise supercooled) air, you might suffer thermal shock and begin to die of cold at the same rate that you would if you were immersed in 32 *F water. You'll die even faster if you're in a dense atmosphere of supercooled helium, hydrogen, or similar thermally-conductive gas.

Last edited by Pursuivant; 01-20-2023 at 11:27 PM.
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Old 01-21-2023, 09:01 PM   #14
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

Thanks!

There's also two different figures for how wind chill works about about 60 mph of wind speed. The current National Weather Service Wind Chill scale has the effects of higher wind speeds past around 60 mph as about flat, with 110 mph winds only a couple degrees colder than 60. The Australian Apparent Temperature uses wind speed, temperature and humidity, and will spit out a temperature either above (which in the US gets used as the heat index) or below from the same equation. 35 degrees F and 100 mph winds results in either 14 degrees F or -27 degrees F. Any idea which figure is closer to the mark?
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Old 01-21-2023, 09:06 PM   #15
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

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T. 35 degrees F and 100 mph winds results in either 14 degrees F or -27 degrees F. Any idea which figure is closer to the mark?
The more accurate one is the one that predicts "Stumble 10 yards in the direction the wind is blowing, then fall down and die before you can get up again.".
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Old 01-22-2023, 02:26 AM   #16
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

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The more accurate one is the one that predicts "Stumble 10 yards in the direction the wind is blowing, then fall down and die before you can get up again.".
14°F is -10°C which is cold, but assuming proper equipment you can be outside for quite a while. -27°F is -32°C which is colder than I've ever experienced.
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Old 01-22-2023, 07:44 AM   #17
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

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14°F is -10°C which is cold, but assuming proper equipment you can be outside for quite a while. -27°F is -32°C which is colder than I've ever experienced.
I walked to class for a mile or so in -28F with strong winds. Wind chill in Chicago that day was supposedly -70F.

The key bit was “no exposed skin.” I had to wear a modern ski goggle to keep my tears from freezing my eyes shut. GoreTex/Thinsulate parka with an internal baffle (elastic membrane that isolated my core) meant I was comfortable in a lightweight shirt. Two layers for pants. Ski gloves.

It was super annoying but it got done.
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Old 01-22-2023, 09:22 AM   #18
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

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14°F is -10°C which is cold, but assuming proper equipment you can be outside for quite a while. -27°F is -32°C which is colder than I've ever experienced.
I've survived 35F myself (and maybe 10 degrees colder). It only gets that cold locally when a cold front comes through but it happens.

However, it was the 100 mph winds that caught my attention. I've survived those too but I did by staying inside my nice solid house. 100 is where the wind starts to _howl_ and being outside at that time would be worth a Fright Check. Even mentally dubious persons who work for the Weather Channel seek shelter at 100 mph. They have no choice.

So rules for what happens to humans fully exposed to 100 mph winds aren't needed.
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Old 01-22-2023, 10:20 AM   #19
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

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Any idea which figure is closer to the mark?
No idea, although my ignorant instinct is to go for the measurement which factors in humidity. Since humidity drops fast below freezing, it would make more of a difference for hypothermia due to cool wet weather than for frostbite or immersion shock.

For game purposes, exact measurements probably don't matter that much as long as the temperature is within +/-5-10 *F. Dice rolls and modifiers for equipment and other factors can be used to get "close enough" results.

The key to modeling cold injury realistically is the continuum of symptoms from numbness and shivering, cumulative loss of FP and attributes, frostbite, hallucinations/ delusions, unconsciousness, and finally death as extremities cool and then core body temperature drops.

In game terms, the important rules are: How long until your hands freeze up or get shaky due to shivering? How long until you can't think clearly? How long until unconsciousness? and, How long until death?
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Old 01-22-2023, 05:26 PM   #20
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Default Re: HT Rolls to Resist Cold - effects of a critical failure?

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However, it was the 100 mph winds that caught my attention. I've survived those too but I did by staying inside my nice solid house. 100 is where the wind starts to _howl_ and being outside at that time would be worth a Fright Check. Even mentally dubious persons who work for the Weather Channel seek shelter at 100 mph. They have no choice.

So rules for what happens to humans fully exposed to 100 mph winds aren't needed.
I missed the wind part. I converted the 100MPH wind into unit I can understand, and that's a shade under 45 m/s.

Iceland is a very windy place (more windy than icy despite the name), and at about half that the weather service and public safety people will have issued warnings about wind. 30+m/s is "Dangerous! Don't go outside unless absolutely f-ing necessary", though the warning is in slightly nicer language.
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