Additional modifiers for extreme cold?

[Bathawk]

Was adapting a unique character concept for Gurps

In a WWII campaign a Superhuman German Soldier....in gurps terms...has the ability to create, say, 2000 gallons of water at a range of 500 yards (40 levels of create with ranged and increased range
Instead of deploying him, say, in the desert. They put him in the mountains. The idea being he can drench allies soldiers soaking wet to increase the chances of hypothermia
Now according to the rules, barring any mitigators like temperature tolerance, someone in below 35 degree weather has to make a HT roll once every 30 minutes, 15 minutes in light wind, with a -5 for wet clothes
But there is no modifier for extreme temperatures. 30 degrees is no more or less an issue than -30 degrees unless I’m looking at the wrong page

Plus would being drenched by a few hundred gallons of water count as “sudden shock”? In say 20 degree weather? I can’t imagine allied soldiers being able to fight normally for another 15 minutes before having to make a single HT roll

[RGTraynor]

Not really. Hypothermia isn't an "instant" effect, unless you've got a heavy wind (in which case the soldiers aren't fighting in -40 degree wind chill, they're in bivouac). It wouldn't take as long as fifteen minutes to be affected, but it wouldn't hit them at once.

[Bathawk]

Originally Posted by RGTraynor

Not really. Hypothermia isn't an "instant" effect, unless you've got a heavy wind (in which case the soldiers aren't fighting in -40 degree wind chill, they're in bivouac). It wouldn't take as long as fifteen minutes to be affected, but it wouldn't hit them at once.

Granted. However I was thinking even if it’s not instant, there would be at least a penalty to the HT roll if things were more than “chilly”. Though the interval is also debateble. After all if 30 minutes becomes 15 minutes in “light wind” isn’t it because the wind chill is stripping heat away? Wouldn’t colder temperatures even bereft if w8nd have a similar impact?

[Bathawk]

Also, would wet clothes increase the temp threshold for HT rolls? In other words, would rolling at -5 in wet clothes at 30 degrees be equal to say an unmodified roll in wet clothes at 50 degrees?

[Rupert]

There is a modifier for more extreme temperatures - on the table (B430) it gives a -1 to HT checks for ever 10 degrees below 0 (Fahrenheit, I assume).

The initial immersion might attract a HT roll for thermal shock, but that shouldn't be ongoing if the victim was merely dowsed in water (but it is a guaranteed loss of 1FP, possibly rather more for average characters).

[Donny Brook]

Originally Posted by Rupert

There is a modifier for more extreme temperatures - on the table (B430) it gives a -1 to HT checks for ever 10 degrees below 0 (Fahrenheit, I assume).

It's weird for the scale of penalties to go from 35 degrees to 0 degrees and then vary by every 10 degrees.

[Anders]

*obligatory metric-system-is-better screed*

[Curmudgeon]

Originally Posted by Bathawk

Was adapting a unique character concept for Gurps

In a WWII campaign a Superhuman German Soldier....in gurps terms...has the ability to create, say, 2000 gallons of water at a range of 500 yards (40 levels of create with ranged and increased range
Instead of deploying him, say, in the desert. They put him in the mountains. The idea being he can drench allies soldiers soaking wet to increase the chances of hypothermia
Now according to the rules, barring any mitigators like temperature tolerance, someone in below 35 degree weather has to make a HT roll once every 30 minutes, 15 minutes in light wind, with a -5 for wet clothes
But there is no modifier for extreme temperatures. 30 degrees is no more or less an issue than -30 degrees unless I’m looking at the wrong page

Plus would being drenched by a few hundred gallons of water count as “sudden shock”? In say 20 degree weather? I can’t imagine allied soldiers being able to fight normally for another 15 minutes before having to make a single HT roll

As the others have said, not really. Being drenched is , possibly, survivable. What puts survival in question in this instance isn't getting wet in the extreme cold but having eight short tons of water dumped on your head at once. If the eight tons all come down in a single hex, on someone who doesn't have protective overhead cover, they're more than likely dead from the impact. If that's not the intent behind the power, you need to spread the water out over a greater area. (For reference an Imperial gallon of water weighs eight pounds. A U.S. gallon is slightly smaller, say 6.4 pounds of water.

Now onto the effects. If the water didn't freeze before it hit, and we'll presume it didn't, the water was no colder than 32°F and might have been warmer. So, our soldier feels wet, but until the heat starts wicking away, he may actually have felt momentarily warmer than than the ambient air temperature. What happens now depends a lot on what our soldier is wearing, but we can make several assumptions. If he's wearing thermal (long-handled) underwear, it's wool, possibly waffle-weaved, which will help out by keeping some of the cloth off the skin. His shirt, olive drab, is possibly linen, but likely cotton, meaning it's insulative value has dropped almost to zero. If he's wearing British-style battledress, his trousers, tunic, tie and socks are wool. Unless he's wearing a forage cap (that peaked hat the police also wear), his head-covering is also wool, and he may have a wool sweater and scarf, as well as wool mittens on his hand. This is important as even soaking wet, wool retains some insulative value. It isn't as good as dry, but it's much, much better than wet cotton. Leather is mostly waterproof, so his boots are okay. Getting them wet didn't do them any good, but given the suddeness of the downpour and the likelihood that he's wearing puttees, or gaiters, and his pant legs are likely 'bloused' above them, it's unlikely that any water got into the boot initially, so his feet may actually be dry, though this may change as the water from his uniform drips into the boot. His webbing is likely canvas, rather than leather, which is a particularly thick weave of cotton, but it has likely been "blancoed", which will afford some waterproofing. Possibly complete waterproofing given the sudden immersion and equally sudden removal from immersion.

The outer jacket may br leather, canvas, or wool, possibly fleece-lined and with either wool, feather or down filling. If the filling is down or feathers, their insulative value is gone as the feathers or down are drenched and clumping together, losing the air pockets that allow them to keep the soldier warm. Leather outer mittens may keep the wool mittens from getting wet.

The soldiers can fight and march, if they have to. If they don't have to, the sensible reaction will be to start several small fires, doff their clothes to dry over the fire and give themselves a good rub-down with a towel to get dry again. The toweling off will be key. If they can do that, they can put their woolens on wet and still be operational for a while. The key questions here will be how long it takes to dry the non-woolens and did sparks get at the feathers/down.

In terms of rapid onset of hypothermia, what you really need is a windchill chart, which indexes wind speed and air temperature. There are several online and at least some of those should show graphically which combinations give a danger of hypothermia and frostbite (different lines on the graph for the two. Absent that, here's a quickie reference point from the Canadian Forces: The 30-30-30 Rule: At -30°F, in a 30 mph wind, exposed [i.e., bare] skin will freeze [this is actual freezing, severe frostbite, not just "Demn, I feel the cold bitterly."] in 30 seconds."

Given the purported use of this Uberman will be put to, with all my heart, I unreservedly wish the member of the general staff, who supported this proposal, a long and storied career, studded with many similar successes.

[Rupert]

Originally Posted by Curmudgeon

(For reference an Imperial gallon of water weighs eight pounds. A U.S. gallon is slightly smaller, say 6.4 pounds of water.

This is incorrect - an Imperial gallon is 10 pounds of freshwater (4.546 Litres). A US gallon is ~8.33 pounds of water (3.785 Litres), and exactly 231 cubic inches.

Now onto the effects. If the water didn't freeze before it hit, and we'll presume it didn't, the water was no colder than 32°F and might have been warmer. So, our soldier feels wet, but until the heat starts wicking away, he may actually have felt momentarily warmer than than the ambient air temperature. What happens now depends a lot on what our soldier is wearing, but we can make several assumptions. If he's wearing thermal (long-handled) underwear, it's wool, possibly waffle-weaved, which will help out by keeping some of the cloth off the skin. His shirt, olive drab, is possibly linen, but likely cotton, meaning it's insulative value has dropped almost to zero. If he's wearing British-style battledress, his trousers, tunic, tie and socks are wool.

British WWII field uniforms didn't have ties. If it's not in the desert, the shirt is woollen as well.

Unless he's wearing a forage cap (that peaked hat the police also wear), his head-covering is also wool, and he may have a wool sweater and scarf, as well as wool mittens on his hand. This is important as even soaking wet, wool retains some insulative value.

He'll most likely have a steel helmet. If the weather is cold, likely with a beanie or the like under it.

The outer jacket may br leather, canvas, or wool, possibly fleece-lined and with either wool, feather or down filling. If the filling is down or feathers, their insulative value is gone as the feathers or down are drenched and clumping together, losing the air pockets that allow them to keep the soldier warm. Leather outer mittens may keep the wool mittens from getting wet.

It's most likely a heavy woollen greatcoat.

[Curmudgeon]

Originally Posted by Rupert

This is incorrect - an Imperial gallon is 10 pounds of freshwater (4.546 Litres). A US gallon is ~8.33 pounds of water (3.785 Litres), and exactly 231 cubic inches.

True. Memory sucks when its been close to fifty years since you've needed information. I remembered that the U.S. gallon was definitely smaller than the Imperial gallon, 10 fl. oz. to the cup rather than the American 8 fl. oz. to the cup and "a pint's a pound the world around" which an American pint wouldn't have qualified for, not realizing the saying was American. In my defence, I grew up in what's considered close to proximity to the Americans.

British WWII field uniforms didn't have ties. If it's not in the desert, the shirt is woolen as well.

I didn't know that, but it's evidently not true for the whole of the Commonwealth. My father's WWII battledress had a cotton shirt and he served in north-eastern Europe (France and the Low Countries). I'm fairly certain that he remarked on tying the tir of his battledress, when teaching me how to tie the knot in my battledress in the late 1960s (which were older surplus uniforms for Royal Canadian Army Cadets and the Canadian militia still wore a version of battledress at this point, but it may only have stretched back to Korea rather than WWII). Pedantically, field uniforms, at least in the 1960s, were a different order of dress from battledress. The canvas trousers (or canvas shorts in hotter weather) replace battledress' woolen ones, the tunic is not worn and a canvas field cap with bill and foldable sun veil replaces the beret.

He'll most likely have a steel helmet. If the weather is cold, likely with a beanie or the like under it.

Yes, he'll possess it, but depending on his branch of service and corps, he may not necessarily be wearing it if the water is dumped in a "second line" area.

It's most likely a heavy woolen greatcoat.

If he's army or navy, but might he have an American-style leather "bomber jacket" if he's air force? And if he's in the American military, most of this won't apply, but I couldn't say for certain what would, beyond woolen underwear and socks still being likely.