Gas Management

[Wijbrandus]

Where can I find information on how to plan out my breathing gas? I've looked on the Internet, and all I seem to find are a ton of classes that have it as one small part.

I've done my AOW, and it hasn't been covered, so I'm figuring that it's time to start learning on my own. Is there a website or a book I should get and read on this to get me going?

Thanks.

 

[Uncle Pug]

If you do a search here on Scuba Board you will find a wealth of misinformation... err... I mean... lots of stuff on gas management some of which is very good and some of which is suspect.

Do a search, read some of the stuff and come back to this thread with some specific questions (including links to any posts the pique your interest.)

 

[VTernovski]

Where can I find information on how to plan out my breathing gas? I've looked on the Internet, and all I seem to find are a ton of classes that have it as one small part.

I've done my AOW, and it hasn't been covered, so I'm figuring that it's time to start learning on my own. Is there a website or a book I should get and read on this to get me going?

Thanks.

search for "Rock Bottom", "Rule of Thirds", etc.. then come back and ask UnclePug again, he usually knows what he is talking about.

 

[H2Andy]

it helped me to "get" the concept:

you plan your gas usage so that at any time during the dive, you and your buddy can get back to the surface on one or the other's gas supply (i.e. one of you can no longer use his or her own air).

different variables (ocean or cave? current or not? drift dive?) will change the details, but the principle is the same.

(ok now i am going to ask for it, but here goes)

my basic plan assumes a surface air consumption of 30
psi/minute, a single AL 80 tank, a 30 feet per minute ascent, a 3-minute safety stop at 20 feet, and a direct-to-the-surface ascent. with those numbers, my rule of thumb is multiply the max depth to be reached by 100psi, add 500 psi, and you end up with your "turn around" psi that will take you to the surface with 500 psi left in your tank.

for example, for a dive to a max depth of 70 feet (under the above conditions), your turn-around psi is 1200.

when diving overhead, i use the rule of thirds.
one third of the gas for the way in, one third for the way
out, and one third is reserved for emergencies.

 

[pipedope]

Make darn sure you always have some breathable gas at all times.
Humans do not breath water and have a very limited time that they can wait for more breathable gas.

UP is right, lots of information here, some good, some bad and some just silly.

Think about what you need to know and how to figure it out.
Things like;
How fast do I use gas?
How much gas do I have available?
How fast does my buddy use gas?
How much gas does my buddy have available?
What happens when there is a problem?

What the heck does 'breathable gas' mean anyway?

BTW The US Navy diving manual is available online and it has a moderate amount of coverage of gas planning.

 

[Curt Bowen]

Where can I find information on how to plan out my breathing gas? I've looked on the Internet, and all I seem to find are a ton of classes that have it as one small part.

I've done my AOW, and it hasn't been covered, so I'm figuring that it's time to start learning on my own. Is there a website or a book I should get and read on this to get me going?

Thanks.

Gas consumption is simple.

Normal divers use from .6 to 1.1 cuft per minute surface equivalent. If your not planning on conducting a required decompression dive, then dont worry about gas consumption. Start to surface when you have from 500 - 1000 psi depending on depth and safety stops required.

Most divers unless they are really overweight or out of shape or really small use about the same amount within a couple hundred psi.

Over the years and after a few thousand dives I know exactly how much gas I need in my head to do all my dives from 50 feet to 500 feet.

 

[pipedope]

Over the years and after a few thousand dives I know exactly how much gas I need in my head to do all my dives from 50 feet to 500 feet.

So Curt, how much gas do you need in your head to dive from 50 to 500 feet?

 

[Curt Bowen]

So Curt, how much gas do you need in your head to dive from 50 to 500 feet?

Just a mouth and nose full each breath

 

[jagfish]

This could get interesting...

 

[ianr33]

Just a mouth and nose full each breath

Just as a matter of interest,how much gas does it take to fill your mouth Curt?