Strange use for Decanter of Endless Water

[Greenfield]

The problem with any calculations of thrust is that you need more than volume/mass per second, you need the velocity its ejected at, and that's just not there. As in, you can pretend to calculate something, based on something, but at the base of it you're making things up and calling them facts.

What are the facts? The item says it can produce a stream of water 20' long and a foot across. In order to have a solid stream of water a foot wide, you need an opening a foot wide.

We know the decanter doesn't have that, but let's pretend it can somehow do that anyway (here's where we enter the realm of "making things up. )

Go get your garden hose and turn it on, hard, without a nozzle of any kind. Aim it up at an angle. Can you reach a target 20 feet away?

If so, you've confirmed about 40 to 45 psi. (Pressure regulators in most city water systems cap it at 50.)

Do you feel that mighty thrust from your hose when you do this amazing feat? (sarcasm intended). There's hardly any, is there.

Multiply it by about two hundred. (Standard hose is 3/4 inch across. A stream a foot across has a surface of Pi x 6 x 6 square inches, or 113.0973333 square inches over all. The hose area is 0.441786 square inches, a bit under a half.)

So sit yourself on a mechanic's creeper or similar wheeled gizmo and see how much speed you can build up with the hose. By my calculations, it won't have enough to overcome the basic friction in the wheel bearings. You won't move.

Multiply by 200? You should reach a screaming 0.75 mph. As in three quarters of a mile per hour, of a quarter of normal walking speed.

Now apply this to a wagon on a muddy road (the roads will be very muddy if everyone is using these.) At 9k per decanter you'll top 200k per wagon, easily. And that's only if you weren't planning on loading anything into the wagon. Hauling cargo would require a lot more decanters.

There are about a thousand cheaper and easier ways to build a self-powered wagon or watercraft.

Sorry to be a wet blanket, but with all these decanters around, wet is the only kind there is.

 

[Greenfield]

Now let's start making up numbers in a different way.

Again, we'll presume that somehow the decanter can produce a solid stream of waer that's larger than the opening.

300 gallons per minute is 30 gallons per round, or about 5 gallons per second.

5 gallons per second through a 1 foot opening is...

Well 231 cubic inches in a gallon, 1,155 cubic inches per second.

The column it produces is a foot across, which is 113.0973336 square inches. One inch of the column (length wise) would be 113.097... cubic inches.

So the water is moving at 10.21244 inches per second, which is about 7 miles per hour.

Five gallons of water weighs 40 lbs . An adventurer, with gear, could be called 200 to 240 lbs.

So one fifth to one sixth the thrust needed to move that adventurer at a hustle

In hard number terms, its about 34 foot-pounds of pressure, give or take a few decimal points

<Edit>
Whoops! Major math foop. I used the Feet per Second to Miles Per Hour conversion, when the speed I had was in inches per second.

Drop things by a factor of 12. End result? A little less than three foot pounds of pressure.

Sorry for the mistake.

 

[nijineko]

I've been trying to come up with cool ideas for a ship that I'll be featuring in my campaign soon and I came up with this one earlier today. It's kinda out there but I was wanting to get some feedback on it.

Glue a bunch of Decanters of Endless Water onto a ship and turn them all onto geyser mode for movement.

I guess mostly I was wanting to get an idea of how fast they could push something and how much each one could push. I was thinking since a DC12 Strength check is required to hold on and since it will take a Strength of 14 to make the check on average then maybe the push of it should be equal to what a Strength 14 human could push. I guess that fact that each one will be pumping 300 gallons a minute might cause problems as well.

Well any feedback is welcome as are any other for making a interesting ship.

well, if you don't mind a bit of 3.0 that made it into 3.5 by virtue of never having been updated, the stronghold builder's guidebook has tons of stuff with which you could outfit a ship, as does stormwrack. in fact, by combining the two, i found that the folding boat (from the dmg) is the equivalent to one stronghold space from SBG. so i treated it as a 1ss stronghold and went to town enchanting it with fun stuff. (think flying, phase shifting through solids, submersible, and more).