Physical properties of Riverine

[Jowgen]

Riverine, from Stormwrack. High pressure water sandwiched between planes of force.

Everyone knows it's useful in that it can give you equipment that's effectively indestructible (unless hit by one of those 'always destroys anything' effects). But what are its actual properties as a material?

I assume that when calculating the price of an object (2000 gp/lb) you go off the regular object's weight, but how much would a cubic foot of riverine weigh/what's its density?

It's immune to physical damage, so hardness/hp are a moot point in game mechanics, but how 'hard' would it be to the touch? If you touch an object made out of riverine, would it be like touching an invisible diamond with water in it, or water that has a thin skin holding it together (surface tension of >9000)? Could you make a nail out of riverine to use in construction?

As an extension of this, how would it behave in terms of friction? Could you file your nails with a riverine nail-file?

Since wall of force blocks just about everything, would I be right to assume that it simply does not conduct heat (perfect insulation)? In that case, would it be like cool to the touch, or...? Alternatively, if it does conduct heat, could the force-sandwiched water within the force change states (e.g. freeze)?

And last but not least, if you hit a riverine shield with a hammer, does it make a sound?


I know very little of this can be reliably answered based on the rules, I'm just looking for ways to adjudicate it in my game in a way that's realistic and immersive (... get it? Because it's water from the bottom of the ocean. :smallcool: )

[Deophaun]

I assume that when calculating the price of an object (2000 gp/lb) you go off the regular object's weight, but how much would a cubic foot of riverine weigh/what's its density?
Well, we know that water's density in D&D is the same as in real life: a half gallon weighs 4 lbs. So, a cubic foot of water weighs a little more than 62 pounds.

The water in a riverine, however, is under extreme pressure, and contrary to popular opinion, water is not incompressible. Stormwrack says it's under pressure found in the blackwater trenches. If these are anything like the Marianas trench, then the volume has been compressed by around 10%. So we're looking at a weight of 68-69 lbs per cubic foot.

This also means the water wouldn't simply "spill" out from a destroyed riverine item; it would explode.

[Kazudo]

I'll answer as much of this as I can without sounding like too much of a brainless moron.


Riverine, from Stormwrack. High pressure water sandwiched between planes of force.

Everyone knows it's useful in that it can give you equipment that's effectively indestructible (unless hit by one of those 'always destroys anything' effects). But what are its actual properties as a material?

I assume that when calculating the price of an object (2000 gp/lb) you go off the regular object's weight, but how much would a cubic foot of riverine weigh/what's its density?
Well, the tricky part here is that you'd be talking about essentially high pressure water. You'd have to know HOW high the pressure is to figure out how dense the cubic foot is and how much it weighs. Now, it's important, this is already kind of weird, because the pressure of water at the bottom of the ocean is entirely due to the weight of the water column on top of it. You're essentially taking water in its pressured state out of what's causing its pressured state and having it retain its pressured state. Which is weird, but ok. Using the phrase "Water from the bottom of the ocean" and extrapolating from Earth, We'll use the Marianas Trench, which exerts 15,750 psi at the "bottom" of the trench. Which is over 1000 times standard atmospheric pressure at sea level. But not much more than 1000, so we'll just use 1000. That means that in this instance, Riverine is under 1000 times more pressure than normal water at sea level. Normal seawater at sea level weighs around 63 pounds (give or take) per cubic foot. I don't know anything about how physics works, really, when it comes to fluid mechanics. However, this is a liquid, not a gas we're talking about. That's about where the edge of my knowledge of physics stops. Business major, you know.



It's immune to physical damage, so hardness/hp are a moot point in game mechanics, but how 'hard' would it be to the touch? If you touch an object made out of riverine, would it be like touching an invisible diamond with water in it, or water that has a thin skin holding it together (surface tension of >9000)? Could you make a nail out of riverine to use in construction?

Water under 1000 times standard atmospheric pressure probably wouldn't ripple when touched. However, the planes of force would be what you'd touch. Probably something to the effect of touching an invisible diamond more than water with a thin skin holding it together. And I'd imagine that you could, though what kind of nail would be difficult to say, since framing nails are so small I doubt they'd have much substance to them. Railroad spikes, maybe.



As an extension of this, how would it behave in terms of friction? Could you file your nails with a riverine nail-file?


That's more a matter of an abraded surface on the nail file than anything else. If you can make a riverine nailfile with an abraded surface, I'd imagine you could.



Since wall of force blocks just about everything, would I be right to assume that it simply does not conduct heat (perfect insulation)? In that case, would it be like cool to the touch, or...? Alternatively, if it does conduct heat, could the force-sandwiched water within the force change states (e.g. freeze)?

Well, I'd imagine you're right here. Wall of force seems to indicate that not even air could get through it, so it's doubtful that heat can radiate through riverine. However, gaze attacks still work, which is really just interesting more than anything. It would probably feel temperature neutral, since you'd be (again, limited scientific knowledge) feeling your own body heat radiating back. As far as freezing, doubtful since it's maintaining perfect pressure and water expands when it cools. Boiling would be interesting, but you wouldn't lose any mass due to the water vapor going nowhere.



And last but not least, if you hit a riverine shield with a hammer, does it make a sound?

I dunno. You might hear the hammer thud as it suddenly and un-uniformely stops, but that's even doubtful. You might make it do it anyway for dramatic effect.



I know very little of this can be reliably answered based on the rules, I'm just looking for ways to adjudicate it in my game in a way that's realistic and immersive (... get it? Because it's water from the bottom of the ocean. :smallcool: )

TRUE THAT. I didn't bother looking up Stormwrack's information on it, so I have NO idea.

[Fouredged Sword]

The object shouldn't change weight. Materials that increase or reduce weight are called out as doing so. My understanding is that the wall of force does all the structure and the water is just added in enough amounts to give the item the correct heft.

[Zombulian]

I never really got Riverine. Sure it's really cool, but if you're making things out of force, why not just that? Why add the pressurized water?

[Metahuman1]

Near as I can tell, cause they needed a way to make it tie in with there book all about aquatic environments.

[Rubik]

It also gives mass to the item. A riverine greatsword has more inertia on a swing than one made of pure force and therefore does more damage.

[TuggyNE]

I never really got Riverine. Sure it's really cool, but if you're making things out of force, why not just that? Why add the pressurized water?

I figure the water is there to provide some tie for the force to connect to and reference. It's kind of the physical focus that makes it useful in various shapes and on the move, rather than just being the broad, flat or gently curving, unmoving walls that otherwise characterize force barriers.

Hadn't thought of the mass explanation, but that also is very reasonable.

Finally, force effects usually let things like gasses through, but getting gas to go through water and then come out again is just about impossible, so it's just about the best seal possible.

[Jowgen]

Thanks everyone for your input :smallsmile:


That's more a matter of an abraded surface on the nail file than anything else. If you can make a riverine nailfile with an abraded surface, I'd imagine you could.

Conversely, could you then also create riverine items with a perfectly smooth surface to create effectively friction-less gears as part of your perpetual energy producing machine design of choice? It seems feasible, as I don't see someone starting a fire by rubbing two sticks of riverine together, no matter their speed/strenght...


The object shouldn't change weight. Materials that increase or reduce weight are called out as doing so. My understanding is that the wall of force does all the structure and the water is just added in enough amounts to give the item the correct heft.

I accept this point for the most part, but the problem is that Riverine isn't limited to any material; so two identically sized items made of different materials, lets say a wooden light shield and a steel light shield, would still weigh 5 and 6 lb respectively when respectively made out of riverine, even though they're identical. :smallconfused:

[Fouredged Sword]

That is why I think the ratio of water to forcefield isn't fixed. The object gets enough water to make it weight the proper amount, then the rest of the structure is made of force field. A wooden shield has more force, less water. A metal shield has more water, less force.

[TuggyNE]

I accept this point for the most part, but the problem is that Riverine isn't limited to any material; so two identically sized items made of different materials, lets say a wooden light shield and a steel light shield, would still weigh 5 and 6 lb respectively when respectively made out of riverine, even though they're identical. :smallconfused:

That … is an unfortunate artifact of D&D treating materials as "ordinary" and "special", rather than having different materials globally listed with their various properties for tools, armor, weapons, walls, doors, and other objects. In such an imagined utopia, you'd have "Shield, heavy", and could make it out of any material you like: hardwood, softwood, steel, iron, bronze, densewood, mithral, and so on.

[Chronos]

Quoth Rubik:

It also gives mass to the item. A riverine greatsword has more inertia on a swing than one made of pure force and therefore does more damage.
Except that most swords are more effective the lighter they are. Axes rely on weight, and some greatswords were basically used as funny-shaped axes, but the ideal one-handed sword would be weightless.