Bigger lungs, greater air consumption

[The Kraken]

Folks, divers that is, are kinda like cars.

Take a big SUV and a sub compact.

You can fill both gas tanks and the two vehicles will take you pretty much the same distance, but it takes more gas to fill up the SUV than it does the sub compact.

More mass requires more oxygen, hence a higher required volume of breathing gas.

Yep, you and that cute little 5'2" sea nymph of a dive buddy of yours will do a 60' dive and when you run out of air, she'll still have 1500 psi left.

That's just the way it is.

the K

 

[DIR-Atlanta]

Here's an excerpt from a handout I use for a seminar I give ... maybe something in there will be helpful ...

That's a pretty good tutorial. One thing I would suggest adding is to reduce (or even eliminate) unnecessary movement. Most newer divers do not really realize how much energy the expend with hand finning and extraneous fin movement to maintain stability in the water. If you are neutral, you should be able to hold position without much movement at all.

Propulsion is also key - get the horizontal trim thing going, and then work on moving horizontally just with fins only. That will help cut down on unnecessary hand movement. Going up or down in the water column can be accomplished mostly through breathing control, so no extra movement is required there either. As you get more stable and efficient with your movement, your gas consumption will drop appreciably.

If possible (and practical), it's a good idea to get someone to videotape you underwater. People are often surprised at how much they move, especially when they think they are "not moving".

 

[TSandM]

It seems intuitive that bigger lungs would equal bigger breaths, leading to high gas consumption. But it's not true.

The determinant of how much air has to move through your lungs in one minute is the amount of carbon dioxide you produce in that minute. Whether you're 5'1" and 100 pounds, or over six feet, if you produce the same amount of CO2, you need the same minute ventilation. The guy with the big lungs just has to take fewer breaths to move the same volume.

Now, it's also true that the big guy generally has more body mass, especially more muscle mass, producing CO2. So he's probably going to require more minute ventilation than a small woman, no matter how their diving skills compare. But it's not because his lungs are bigger. It's because HE'S bigger overall.

There are very good tips for reducing gas consumption in the posts above. The biggest one, in my opinion, is the one in my sig line: One you realize that diving is about floating, rather than swimming, you're on your way to better technique and reduced gas consumption.

 

[scubanimal]

Suddha,
Generally I see it takes about 50 dives before people really relax enough to get their effciency up to near peak on air use. If you are a good athlete and are in excellent shape, then your O2 consumption rate just will not allow you to have a low SAC rate without raising your CO2 levels, and that is not good. This is one area being a bit out of shape is a bit of an advantage. But with proper diving skills you can still be very good on air.

As was said before long slow deep breaths. I too am a big guy, with very large lungs, and am on the very low side of air usage now. Plenty of good advise has been said already, but to help you visualize it here's another take.

Those who are really good on air get into a 'zen' while diving. I'll not go into the technical view but you will find soon enough, that you'll get to interacting with something lots of time will go by and you'll find you hardly used any gas. It has to do with your not 'thinking' about breathing just like you do when you're not diving. However to get to that point you need to develop good dive habits, like long slow deep breaths, excellent bouyancy skills and such.

There are a few tricks to help yourself, for instance remember when in early grade school and you were told to carry a musical note, by going aaaaaaaaaaaaa try that and you'll see you can carry that on for a very long time. Try doing that while diving. Another trick is to use your snorkle on the surface for a couple minutes 'preparing' for the dive. Someone could write a book on this but for now just get out and dive, stay relaxed, take your time, and really enjoy what you're doing.

As far as why most women use less air, there are a few reasons, one, generally their muscle mass and resulting need for O2 and two their lack of ego. Many guys I've dove with that are relatively new, still swim a bit fast, a bit of gotta get there attitude. By taking your time and really looking at and for small animal will help develop a slow pace, resulting a lower consumption need for O2. Combined with good breathing patterns will result in your air supply lasting longer. Try letting your wife lead the dive and see how that changes your pace.

So go dive, enjoy and don't worry about it, with experience and dive skills it will come.

 

[Drewpy]

Ive been there too..being a big guy. Just keep diving and dont put pressure on yourself
It will all work out as you keep diving..I now have the same consumption as my buddy who is much smaller.Dont worry about it and just enjoy yourself..it WILL improve!

Drew

 

[Mr.X]

Ive been there too..being a big guy. Just keep diving and dont put pressure on yourself
It will all work out as you keep diving..I now have the same consumption as my buddy who is much smaller.Dont worry about it and just enjoy yourself..it WILL improve!

Drew

I agree with the statement above. The last thing you want to become is a competitive about how much gas you use during a dive. I know some instructors who used smaller tanks boasting how little gas they used during a dive. They were skip breathing, but not telling anyone. Additionally, they created a cadre of newbie divers always looking to equal their instructor by doing the same thing. Funny thing is when you instruct, you should be carrying ample gas vs. using the smallest volume possible.

My personal feeling is you use the gas you use during a dive. Sometimes when you are working hard, you'll use more gas. Diving in frigid water, or warm water can change consumption big time. So does activity. Personally, I got myself a rebreather because I didn't want to worry about the gas consumption clock during big, deep dives. Gas consumption is no biggie these days...even on OC.

X

 

[Pearldiver07]

When I started I was called "The Terminator" because I would drain a tank so fast.

The only thing I would add to the above is that I would suggest to not change the natural rythm of your breathing, nor force the rate. Your body will make up for any perceived attempt of an artificial pace of breathing.

Remember, it's not just the finning. Any other additional movement or straining to hold a particular posture causes increased consumption. And all of the advice about relaxing is so true.

I always try to convey to students that scuba has a "zen" side to it. The harder you try to relax, the less you will. Just let it go, don't worry about it too much, and get LOTS of dives under your belt. When all of the activities become second nature you'll consume less than before.

Bottom line: Why are you reading this when you should be underwater??!?!?

 

[cinder4320]

In addition to just time and experience, it also helps if you learn to breathe from your diaphragm. If you've ever played a wind instrument thats the first thing they teach. Women often do so naturally but not men.

To check, breathe in deep. Your stomach should be moving out not your chest. If you google "Diaphragmatic Breathing" you'll find websites that teach how to do it.

Miranda

 

[Pearldiver07]

Personally, I got myself a rebreather because I didn't want to worry about the gas consumption clock during big, deep dives.

X

Oh yeah! Like you need an excuse to go get a rebeather??!?!

 

[Mr.X]

Oh yeah! Like you need an excuse to go get a rebeather??!?!

While it's a side benefit of having a rebreather (not worrying about the gas consumption clock) the real reason I use rebreathers is because they fit the job description. Some of the jobs required the use of autonomous divers penetrating spaces where tethered divers couldn't go.

X