Underwater Adventuring

[Steverooo]

The Bends" Kills Fish, Too!

Although how and why might surprise you!

http://www.hq.usace.army.mil/cepa/p...may00story8.htm

 

[Steverooo]

Ker-Plooie!

I'm sure you've heard of certain deep-sea species who decompress, explosively, when brought to the surface?

I MUST use that as a weapon, now

Kinda gives a whole new meaning to Wall of Ice, don't it?

 

[Steverooo]

Although they aren't unique to SCUBA gear, the gear does make it much worse.

When you are using SCUBA gear, you are breathing in compressed gas. The best way to think about this is probably with a plastic bottle.

If you fill a plastic bottle with air at the surface (not compressed, just atmospheric pressure) and take it down, it will compress in. When you take it back up, it pops back out. The thing it is doesn't burst.

If you take a plastic bottle down with you and fill it from your tanks while you're below water (depth of about 60' should be more than enough), then seal it with the cap and try to bring it up the bottle will burst. The air to fill the bottle was compressed (matched the pressure of the surrounding water) and as you brought it up the outside pressure is reduced causing the air inside to try and expand.

It is still simple physics, pv=nRT, but in the second case you've filled something with more than it can hold at surface pressure.

SCUBA gear neither causes the problem, nor makes it worse. To illustrate, let's take a very simple example...

A free-dive pearl diver is farming pearls at 150'. Before jumping in, he exhales, picks up a large rock, and dives in. He quickly sinks to 150', where he enters an underwater cave, recovers from any nitrogen narcosis he may be suffering, and then takes a deep breath, and goes out to search for pearls. When he runs out of air, he re-enters the cave, breathes, and then exits to return to the surface...

No SCUBA tanks involved. Does he suffer the bends? Yes.

Why? Because he was breathing. The air in the cave is also under pressure (if it weren't, the water would rise into the cave until the pressur equalized).

The point is, any air you can breathe, underwater, is pressurized. It doesn't matter if it's in your lungs, bloodstream, SCUBA tank, wineskin, or an underwater cave! When you breathe down there, you have to decompress on the way up, or get the bends.

All sans magic, of course...

 

[Anabstercorian]

SCUBA gear neither causes the problem, nor makes it worse. To illustrate, let's take a very simple example...

...The point is, any air you can breathe, underwater, is pressurized. It doesn't matter if it's in your lungs, bloodstream, SCUBA tank, wineskin, or an underwater cave! When you breathe down there, you have to decompress on the way up, or get the bends.

All sans magic, of course...

Unless, of course, you breathe water, or you simply hold your breath after breathing air at the surface.

 

[Liminal Syzygy]

The point is, any air you can breathe, underwater, is pressurized. It doesn't matter if it's in your lungs, bloodstream, SCUBA tank, wineskin, or an underwater cave! When you breathe down there, you have to decompress on the way up, or get the bends.

Actually you don't always have to "decompress" (which many define as stopping at a specific depth for 5 minutes or so) depending on how deep you have gone and how long you have been down. However no matter how long you have been down it is always important to surface slowly to allow yourself to "naturally" decompress.

I assume a potion or spell of water breathing would avoid any issues with the bends since you are basically extracting the oxygen from the H20 and there is no nitrogen involved. But that's just an amateur's assumption. Anyone have any insight?

Also, helms of underwater action and the like could definitely help considerably with the bends by magically varying the mixture of gases you breathe at certain depths, although not completely eliminate the danger.

 

[Steverooo]

Unless, of course, you breathe water, or you simply hold your breath after breathing air at the surface.

Breathing water doesn't prevent bends. See the stuff on fish explosively decompressing, and getting the bends. It does, however, seem to lessen the effects.

Holding your breath is hardly an option, for Humans. You can't get very far that way...

 

[Steverooo]

Actually you don't always have to "decompress" (which many define as stopping at a specific depth for 5 minutes or so) depending on how deep you have gone and how long you have been down. However no matter how long you have been down it is always important to surface slowly to allow yourself to "naturally" decompress.

I assume a potion or spell of water breathing would avoid any issues with the bends since you are basically extracting the oxygen from the H20 and there is no nitrogen involved. But that's just an amateur's assumption. Anyone have any insight?

Also, helms of underwater action and the like could definitely help considerably with the bends by magically varying the mixture of gases you breathe at certain depths, although not completely eliminate the danger.

Oh, WotC COULD have settled all the questions, and just said that ALL of the underwater magic items and/or spells protected from all of these problems... They COULD have done it, IF:

A) They had ever bothered to mention the problems, and
B) Stated that the spells and/or items did or did not prevent damage from them!

As I said above, I think WotC missed a few points (and T$R, before them). These problems have been around since 1e...

 

[Aeolius]

Holding your breath is hardly an option, for Humans. You can't get very far that way...

Feel free to roll up an unaltered human PC for my underwater campaign and we'll find out.

These problems have been around since 1e...

and before that... http://store.yahoo.com/svgames-store/tsr9277esd.html

 

[Mystic Eye]

Oh, WotC COULD have settled all the questions, and just said that ALL of the underwater magic items and/or spells protected from all of these problems... They COULD have done it, IF:

A) They had ever bothered to mention the problems, and
B) Stated that the spells and/or items did or did not prevent damage from them!

As I said above, I think WotC missed a few points (and T$R, before them). These problems have been around since 1e...

Steveroo, I hope you know I was just kidding about the de-railed thread thing! I meant no insult and hope you did not take it that way. Just my twisted humor.

 

[AnthonyJ]

Breathing water doesn't prevent bends. See the stuff on fish explosively decompressing, and getting the bends. It does, however, seem to lessen the effects.

Fish explosively decompress for reasons other than the bends; they have a gas-filled gland used for altitude maintenance. If a human breathing pressurized air were to gain altitude rapidly without exhaling, his lungs would rupture for the same reason. The sinuses are also an issue, but that's about it for sections of the body that contain gas. If you flood all of them with water, going up and down won't have severe effects; anything which isn't gas-filled is largely incompressible.

I suppose oxygen bubbling out could cause the bends, but you don't normally want partial pressures of oxygen much higher than surface level anyway, so I doubt that water breathing results in ultra-compressed oxygen in the body.