Additional modifiers for extreme cold?

[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.

[Rupert]

Originally Posted by Curmudgeon

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.

The US copied, in a modified form, the British blouse, so that's be wool (and did have ties). When properly ironed, etc. their uniform looked smarter than the British battledress, which was modeled on skiing sportswear, so was loose to enable easy movement, fitted with pockets that were designed to lie as flat as possible to not snag on things (including bits of vehicles), and which put utility ahead of appearance.

In WWII the British used for BD most situations that weren't dressy enough to require 'service dress' or some kind of dress uniform, aside from maintenance work for which they had an over-sized version of battledress made of denim (and intended to be worn over normal BD). In hot climates the uniform was of cotton, with shorts and a short rather than a 'blouse', and other differences, but it was based on the same design.

This battledress was widely copied, so they must've done something right.

[Inky]

I'm not sure about any of the following.

Whatever kind of gallon you use, Create Water 40 would produce 10 lbs x 40 x 40 = 16,000 lbs of water, which isn't actually as much as it sounds, it would all fit into a two-metre cube - so you couldn't cover all that large an area at once this way, for instance it would cover an area around 9 metres square 10 centimetres deep, or an area 4 metres square 50 centimetres deep.

(On the other hand, as Curmudgeon says, if the superhuman is able to drop the entire 16,000 lbs from a height on a small group of soldiers, they might be killed just by the weight - you'd think that wouldn't happen, but people can break bones falling from a height into water. You might have to buy that as an Alternate Ability).

"Thermal Shock" specifically says "sudden immersion", and it's talking about rolling once every minute while you're immersed in water, whereas with this they'd be immersed (as opposed to just wet) for very much less than a minute. As Rupert says, if you did allow it, it would only be that once, but after that it would just be ordinary standing-in-a-cold-place-in-wet-clothes, so roll after a minute and then roll every 15 minutes after that.

It seems like the Cold rules leave a bit to be desired in this case, though - if that's the only effect the water has, then it would be 15 minutes before anything happens at all, and they wouldn't be at any penalties until they got down to 1/3 FP, which could take a lot longer.

I'd be inclined to say that having icy water thrown over you should also inflict a sizeable shock penalty even if it doesn't actually inflict any damage. Maybe even a Fright Check the first time (indicating seconds lost working out what had just happened and which way up they were, rather than fright) if they're not expecting this.

Also an increased Malf on their weapons until they can dry them out - I'm not sure exactly how much guns and ammunition would be affected by having water thrown over them (maybe somebody here knows) but it doesn't seem like it would be a good idea.

If you've just dumped eight cubic metres of water over a smallish area of ground on which people are running and fighting, that ground might also become Bad Footing before too many turns are over.

It looks like this would have tremendous nuisance value but would be more use as defence than offence, unless the idea was that other soldiers would be waiting to pick them off - if there was some place that needed to be protected, this would be useful in preventing the enemy from attacking properly and possibly forcing them to retreat to get dry before hypothermia became an issue, but it'd be unlikely to kill anyone - unless he could do what Curmudgeon suggested.

[Varyon]

Originally Posted by Inky

(On the other hand, as Curmudgeon says, if the superhuman is able to drop the entire 16,000 lbs from a height on a small group of soldiers, they might be killed just by the weight - you'd think that wouldn't happen, but people can break bones falling from a height into water. You might have to buy that as an Alternate Ability).

Water doesn't compress well, so if the relative velocity is too high for the water molecules to get out of the way, it functions very similarly to a solid surface. xkcd did an interesting What If? about all the precipitation from a storm falling as a single drop; from its starting position 2 km above the ground the giant drop builds up to around half the speed of sound before hitting the ground. Of course, that was about 600 million tons, as opposed to the mere 8 tons of our ubersoldat, so the single droplet involved here is going to have a lower terminal velocity and also be more susceptible to dispersal by air resistance (and the dispersed bits are going to decelerate fairly rapidly to fall at the same sort of velocity rain normally falls at, somewhere around Move 10). There's probably a sweet-spot height to maximize both the velocity and the size of the remaining drop (to maximize the amount of damage it will cause on impact), but I don't know enough of the physics to calculate it or determine if it would be enough to cause significant damage. However, if the character can create water at the ambient temperature - in which case it will be ice - that simplifies matters, since now it's just a falling solid object. A 500 yard drop (dropping it on top of oneself) would result in a velocity of around 100 yards per second; that's right around maximum human terminal velocity (for a dive), and I would expect an 8 ton chunk of ice to have a higher terminal velocity than a human (they're close to the same density, but the ice is a lot heavier), so that's probably acceptable. Ignoring the multiplier for homogenous (I hate the fact a human-weight ballistic dummy does 4x as much damage as an unconscious human in a collision), 16,000 lb would have around 50 HP, and thus this would deal an impressive 50d cr (with the multiplier for homogenous, this becomes 200d cr). If instead dropping it at a 45-degree angle from the character's position - that is, around 350 yards out and 350 yards up - that gets reduced to a still-respectable 86 or so yards per second, for 43d cr (or 172d cr with the homogenous multiplier). You'll probably only hit one person (if any) with such, however - such a sphere of ice would only have a radius a bit north of 2 yards, and with 8 seconds to react people will probably scatter before it lands. You might be able to justify treating it as though it were an explosive; 16,000 lb at 100 yards per second produces a bit north of 30 MJ of energy, equivalent to around 14.5 lb of TNT, which in turn deals around 45d cr ex; that will cause minor wounds (1 HP) out to 50 or so yards, major wounds (6+ HP) out to around 9 yards, and potentially-fatal wounds (20+ HP) out to around 3 yards. I'd also be inclined to toss in a "free" [1d] fragmentation effect from ice shards and similar (akin to the incidental fragmentation of an explosion in a heap of scrap metal). There's probably a way to purposefully design it to fragment - say, a shell of ice around a sphere of water - but I don't think default Create allows for that sort of control.

[Pursuivant]

The original rules for Immersion Shock back in GURPS 3E were specifically designed for people who plunged into sub-freezing to near freezing water (~-1* C to 1-2* C).

It's your choice as to how cold your super-nazi's water is when it's created, but if it starts off a room temperature it isn't going to have enough time to cool significantly on its way down if it's created 500 yards in the air. If anything, c. 20 *C water created in -10 *C temperatures would briefly warm anyone it hits before becoming cold and making the squaddies' lives even more miserable.

As for collision damage, consider that each soldier will only be hit by the weight of the water directly above them (i.e., no more than 1 hex) and it won't all hit at once. Effectively, it's a "soft" object even if physically it's not. That means a column of water which is nominally ~20 cf/0.5 m3 with a mass of 500 kg (~1100 lbs.) might actually only hit as if it was a soft 50 or 100 lb. object or possibly even lighter. That damage might also take the form of Knockback, at least in part. Probably capable of killing small animals or injuring people, but but not as lethal as if it was a solid chunk of ice.

At the risk of threadjacking, there was a relatively recent thread on a similar topic here.

I proposed a bunch of rules to make exposure to Cold more of a hazard if combined with high winds or if you're immersed in water. Not RAW, but they might help when combined with the other good suggestions on this thread.

As to gear the victims are wearing, I'd imagine that any well-equipped soldier fighting in temperatures where it could get cold would be dressed in layers of water-resistant material. Overcoat, 2+ wool shirts & layers of trousers, thermal underwear, etc., wool cap, 2+ layers of socks worn under boots, insulated leather gloves, possibly with mittens worn over them.

Thick tight-woven wool is fairly water resistant, so it will take a bit of time for the water to soak in. Call it 2-3 minutes. Once victims are good and wet, wool and similar materials retain about 80% of their original insulation value when wet. Considering that the victims are likely to be very physically active, they're not going to freeze to death any time soon. Say that being soaking wet in wool reduces the bonus that Winter Clothing provides vs. Cold to just +1. (Things would be different if they were all dressed in a single layer of cotton fabric. Cotton, etc. don't insulate that well when wet, so any bonus they'd normally give vs. Cold would turn into a -1 penalty once they're soaked, or even higher if there's a high wind to quickly wick away the moisture & cool them further)

Of course, operationally, your super-nazi's water attacks could be a serious problem. Reducing a bonus of +2 for cold weather gear to +1 might mean 5-10% more casualties due to cold from frostbite, trench foot and hypothermia as well as decreased equipment reliability. Repeated attacks over time could turn a routine troop movement into a disaster.

[DeadParrot]

To see the effects of water drops, study wildfire water drops from choppers. If it has time to spread due to distance of fall, probably not going to be fatal but injuries would be likely. If the soldier has no warning about the impending drenching, possible equipment might be damaged. Unprotected radios and bags of powder for large artillery for two examples.

Since 'Polar Plunges' are regularly survived by the participants, I doubt the drenching itself would cause much issue. Long term effects will depend on the local weather.

A large surprise water drop of any temp would be a good way to take out a command tent and the related maps and intelligence info plus injure leadership. Or take out the mess facility just before meal time.