How conserve air when necessary

[MichaelMc]

Does more complete exhales help any? As CO2 drives the urge to breath and other effects, would more effectively flushing it out help?

 

[Hank49]

I'm not sure I could get into a more relaxed state in the few minutes I would be working on cutting myself free of fishing line, kelp or gill net.
I free dive and it takes me about ....half hour or more to get to a state where my average dives go from 50 seconds to 1 min 45 sec or even 2 min. It's like a switch that turns off or something. I know when I get there because I start urinating a LOT. Every 15 minutes or so.
I've been lucky and never been entangled. I think about it a lot. One thing I learned in a free dive class is that I can hold my breath a lot longer than I thought I could. It's not comfortable, but you can go a minute or more past that feeling of "I HAVE TO BREATH".

 

[MXGratefulDiver]

Easiest way to conserve air is simple ... stay calm, work deliberately to resolve whatever the problem is, concentrate on fixing the problem without undo exertion.

Most times someone encounters a problem their air consumption rate goes up due to them getting excited, or exerting themselves more than they have to while addressing the problem. Focus instead on keeping a steady breathing rhythm and maintaining a level of physical calm that'll not only keep your air consumption rate steady, but also help you focus on getting yourself out of whatever trouble you're in. You'll also avoid the buoyancy control issues that often come with exertion and excitation.

It's usually the case that the quickest way to resolve any problem is to slow down ... and that'll improve your air consumption more than skip breathing ever will ...

... Bob (Grateful Diver)

 

[tphelps]

+1 agreeing that holding your breath is a bad idea in the situation you described. Obviously you want to manage your metabolism such as staying warm and calm.

There's always the old school technique of rebreathing your BCD. I wouldn't recommend if you don't routinely sanitize your bladder, but in a hypothetical life or death situation...

Here's an article I wrote for my local magazine on "Improving Your Air Consumption" (pg 16). It won't be too helpful with this specific scenario but might give some good background. March 2017

 

[cipherbreak]

Plenty of people have already given you the "remain calm" answer. I think the best way forward is to have a plan. Know what you would do in an entanglement. Be familiar with your tools (knife, shears, et cetera) and their location. Practice the and don off and don on of your rig underwater and other techniques that may prove vital to resolve a situation. That is a two-fold approach. It may help you resolve an entanglement faster and remain calm during the process, which will decrease your gas consumption.

@tphelps mentioned rebreathing your BC. That is an option, I guess. Mold in the bladder is a concern, but then again so is running out of air. I remember reading you can re-breath your exale up to a dozen times before the oxygen content will not be enough to prevent starvation. At that point you could rinse and repeat, dumping a new puff of gas into the wing.

I think this reinforces the need of taking care of your equipment: properly cleaning, disinfecting, and drying your BC. It gives zippered wings a minor advantage against sealed wings, because you can readily inspect your bladder for mold.

 

[Bob DBF]

@tphelps mentioned rebreathing your BC. That is an option, I guess.

Na, unless you have CO2 absorbent in your BC, you would just be increasing the CO2 level you are breathing.


Bob

 

[cipherbreak]

Na, unless you have CO2 absorbent in your BC, you would just be increasing the CO2 level you are breathing.


Bob

Sure and no one is advocating for doing this for an extended amount of time--or even at all. The question was about a very specific scenario where being out of gas is imminent and the possibility of doing an emergency ascent--controlled or buoyant--is not available.

 

[Doby45]

Sure and no one is advocating for doing this for an extended amount of time--or even at all. The question was about a very specific scenario where being out of gas is imminent and the possibility of doing an emergency ascent--controlled or buoyant--is not available.

In that situation you are dead, why bother with a lung infection to boot.

Out of gas - check
Ascent not available - check
One breath of crappy BC wing air - check
DEAD

 

[northernone]

The calm is the only successful technique I know.

Here's a little unscientific research I have done on myself:


Regarding skip breathing: If I stretch my breathing by holding (strictly every breath) a few seconds longer than comfortable I can get 30% more dive time on a tank but surface with a co2 headache.

Regarding bcd rebreathing: I've dove my rebreather with no scrubber on 21% air (no o2 added, strictly semi closed circuit) out of curiosity of this tip. It is a horrible experience of co2 build up and one of the toughest mental battles I've had on a mundane dive. I could get 3 breaths out of 1 before needing to vent and exhale fresh air. I also bailed out after 15 minutes of near hyperventilating and intense focus. I could not have worked to untangle myself or any other meaningful task while in that state. But I did effectively take 5 minutes of air (estimated from my normal SAC) and make it last 15.

Regarding breath holding: In my photography dives where I practice extensive breath holding on scuba my air consumption is always worse than with a regular respiratory pattern.

My advice, calm yourself and keep breathing.

Regards,
Cameron

 

[Bob DBF]

The question was about a very specific scenario where being out of gas is imminent and the possibility of doing an emergency ascent--controlled or buoyant--is not available.

At that point you might want to make peace with the deity of your choice.

Remain as calm as possible, work the problem, drop your belt before you panic. Saved my ass.



Bob