Huge air consumption even after +200 dives

[lowwall]

People overcomplicate this. Your consumption rate is the volume of your inhale multiplied by the rate of your breaths. Don't try to cut down the volume of your inhale, that leads to CO2 retention. So what is left is the breathing rate.

Breathing underwater has one tremendous advantage when it comes to breathing rate. The number of oxygen molecules in each breath is significantly larger than you get at the surface. The result of this is that if you can keep your work load reasonable, you can take fewer breaths per minute than at the surface without any concerns about depriving your tissues of the O2 they need.

But you do need to worry about CO2 buildup, so long inhales or long inspiratory pauses (holding your breath) are a bad idea.

That leaves you with the exhale. Long exhalations are the key to decreasing SAC rate while keeping CO2 under control. Breathe out slowly, really let it dribble out. You can easily take it out to 15 seconds if you are just cruising along. I can do 20 second exhales on a drift dive at depth. Remember at 20m you get three O2 molecules for every one you get at the surface.

When you are done with the exhale, don't try to lengthen the inhale, just take a nice deep breath and start your exhale again.

You said your current pattern is 4 secs in and 4 to 6 out. Make that 3 in and 12 out and you've cut your SAC rate by at least 33%.

 

[LFMarm]

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[davehicks]

Try to "pulse" your inhales and exhales. Like a little sip/puff on a 5 count for inhale/exhale. You don't need to gulp and blow in a big stream. This becomes very natural with just a little practice.

 

[lowwall]

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Is that video satire?

It is absolutely terrible. Seriously he gets almost everything wrong. He recommends a 3 second inspiratory pause at the end of an exhalation, shallow breaths, and using your BCD inflator to make minor changes in your bouyancy.

He also doesn't understand inertia. He shows the body ascending and descending during each inhale and exhale, but in reality it takes time for your body to ascend or descend in response to changes in your volume. The changes due to breathing basically cancel out.

 

[LFMarm]

Is that video satire?

It is absolutely terrible. Seriously he gets almost everything wrong. He recommends a 3 second inspiratory pause at the end of an exhalation, shallow breaths, and using your BCD inflator to make minor changes in your bouyancy.

He also doesn't understand inertia. He shows the body ascending and descending during each inhale and exhale, but in reality it takes time for your body to ascend or descend in response to changes in your volume. The changes due to breathing basically cancel out.

I don’t disagree. I wanted to share because there are other points of view on gas consumption and breathing. Without getting in the merit of the points he is making, this works for him. I saw him in the water and he has almost perfect buoyancy and pretty low SAC from what he shared.

 

[DreadnoughtNH]

100s and 120s are 7.25 inches in diameter, same as an AL80. 117s and 133s are 8.0 inches in diameter.

Then perhaps what is being given to me is a 117/133. Either way they still don't fit in the racks.

 

[dmaziuk]

Breathing underwater has one tremendous advantage when it comes to breathing rate. The number of oxygen molecules in each breath is significantly larger than you get at the surface. The result of this is that if you can keep your work load reasonable, you can take fewer breaths per minute than at the surface without any concerns about depriving your tissues of the O2 they need.

The number I see quoted everywhere is

O2 inspired = 21% by volume; O2 expired = 16% by volume
O2 change = 5% by volume = 5*500/100 = 25 mL

Which means your breathing rate on the surface is not limited by the amount of O2 in the mix. It follows that raising PPO2 -- by raising pressure and/or O2% (as in Nitrox) -- will make absolutely zero difference to your breathing rate.

Sorry.

 

[happy-diver]

Whenever I have attempted any of these weirdo techniques I forget after three breaths
and just get on with diving breathing, whichever way I might breathe, when I go diving

My figures have indicated, that as you go diving you get plenty of practice from events unexpected as they occur without the necessity to spend diving time, practising events

 

[lowwall]

The number I see quoted everywhere is


Which means your breathing rate on the surface is not limited by the amount of O2 in the mix. It follows that raising PPO2 -- by raising pressure and/or O2% (as in Nitrox) -- will make absolutely zero difference to your breathing rate.

Sorry.

Congratulations. You have discovered that you can safely lower your breathing rate by extending your exhale on the surface as well. Somebody should tell singers and bagpipers about this.

Which, by the way, is evidence of the safety of this approach despite it feeling unnatural at first.

The higher PPO2 is an advantage because it allows you to maintain a slow breathing cadence for a longer period of time and/or at a higher workload than you can at the surface.

 

[Eric Sedletzky]

Maybe you just use what you use, that’s just you and nothing to be ashamed of.
You need to figure out a way to get a bigger tank.