Breathing technique

[TSandM]

This is a very common worry for newer divers. High gas consumption is multifactorial. If you'll forgive me the offense, I'll repost an essay I wrote a while back on the subject:

How fast you use your gas is determined by two things: How much CO2 you are generating per minute, and how efficiently you use the gas you breathe to accomplish gas exchange in the lungs.

To address the second idea first, I'm going to describe a little anatomy. Your respiratory system includes your mouth, larynx, trachea, large bronchi, small bronchioles and then the air sacs where gas exchange actually takes place. Until gas gets into the air sacs, it's just passing through -- it's not delivering any oxygen, or taking away any CO2. If the volume of air you breathe with each breathe is only the volume of your larynx, trachea and bronchi, you're moving a lot of air, but not exchanging any gas. That's why shallow, rapid breathing runs through your tank quickly (and also leaves you feeling short of breath). It's also why slow, deep breaths are routinely recommended by instructors.

Tension and anxiety tend to make people take quick, shallow breaths, which are inefficient. Relaxation tends to allow people to slow their breathing . . . but the funny thing is that slowing your breathing also tends to bring relaxation with it. That's the essence of yoga breathing, or meditation.

Assuming your breathing PATTERN is an efficient one, then you have to look at your CO2 production, which is a result of metabolic activity in cells. You have a certain basal metabolic rate, below which you really can't go. It's actually HIGHER in fitter people than it is in the unfit, so you'd think that getting fit would make your gas consumption worse. But at the same time that your basal metabolic rate increases, the amount of muscle effort you need to accomplish a given amount of work goes DOWN, and that's a much bigger influence. So fitness does pay off.

But efficiency pays off even better. Every motion you make underwater, you pay for with some gas used. Therefore, the less motion, the longer your gas lasts. You can reduce motion by becoming horizontal, so that all your kicking effort succeeds in propelling you forward. If you are tilted at a 45 degree angle to the bottom, each time you kick, you drive yourself upward. To compensate, you have to keep your buoyancy negative, so you will have an equal tendency to sink. At that point, you are expending energy for a net displacement of zero! Very inefficient, and a very common new diver error.

Use your fins, not your hands. Hands are great for swimming on the surface, without fins, because your feet aren't very efficient propellers. But fins are, and that's what you should be using underwater. Flailing wildly with the hands uses a lot of muscle effort and produces very little net propulsion, so people who swim with their hands tend to suck gas.

Master your buoyancy. Although the volume of gas going into your BC or drysuit is relatively small, if you are putting it in and letting it out and putting it back in and letting it back out . . . after a half hour, your BC has breathed a lot of your gas. To master buoyancy, you have to start with proper weighting, because being significantly overweighted will make you unstable in the water column, and result in a lot of yo-yoing that wastes BC gas and ALSO makes you breathe harder. So reducing your weight to the proper amount will, in the long run, make your gas last longer.

And finally, move slower! One of the major strategies of sea life is camouflage, so if you move quickly, you miss many animals you might otherwise find. Unless you have a specific purpose for rapid movement, like spearfishing (and spearfishermen are NEVER going to win any awards for low SAC rates!) slow swimming will result in a much more productive and interesting dive.

Finally, recognize that body size and muscle mass will have a detectable effect on gas consumption. My favorite dive buddy is 6' tall and very strong. He's an absolutely beautiful diver -- quiet, relaxed, balanced and efficient in the water -- but he will never equal my SAC rate, because I'm a little old lady. If you habitually dive with people who are much smaller than you are, then buying bigger tanks may be your best answer.

 

[mallbritton]

As a new diver myself I can say that the advice to give it time and practice is very good advice.

I got certified in Oct. '10 then went on a two week dive vacation to Belize in Dec./Jan. My first few dives in Belize I was the one ending the dives because of low air at about 30 minutes. As I got more experience my bottom times went up and by the end of the two weeks I had extended my bottom time to about 45 minutes, which I was very happy with.

So as has been mentioned... get your weighting right so your buoyancy is good and dive more so you get more experience and you'll extend your bottom time naturally. I'm still struggling with my buoyancy, but I'm getting a handle on it and that makes a lot of difference for me.

Regards,
Michael

 

[Robert Gillcash]

A hint I try to pass on to new divers or even experienced ones who seem to go through air like its free:

Don't use your hands / arms unless it's necessary - like to turn around quickly.

I teach my students to hold their hands together in front of them when they dive.

Multiple reasons for this...

#1 - keeps them from swimming with their arms. Does little to help movement and just ires them out faster and uses more air.

#2 - gets them to hold their gauge package right in front of their face! really easy to do a quick check - pressure, depth, time - and back to the fishes. Also, this keeps the guages right handy at all times, rather than feeling aound behind them and fumbling around and then, ahhh, forget it, too much hassle! I know how much air I have....

#3 - gives them an extra layer of protection for their head - ever get distracted by something at the side and look that way only to bump into something with your head?

Virtually everyone I have gotten to do this says they notice an immediate increase in comfort and a reduction in air consumption.

A side benefit is with their hands full, they are less likely to be inflating and deflating the BC every 2 seconds to adjust their bouyancy needlessly.

Give this a try, I am sure you'll like the results!

 

[Scuba.com]

So many good pieces of advice here. One of the common sense ways I try to relate this to not only my students but instructor candidates as well (so don't feel bad) is to relax. Easy to say. Hard to do at times. But an easy way to work on this, as well as your weighting, buoyancy and everything else we relate to you, is to keep your dives simple and reletively shallow.

Here in Orange County we have the benefit of shore diving that normally doesn't get terribly deep. For most of our dives in Laguna Beach, in order to get 50 feet on your gauge you need to dig a hole in the sand. At those depths, you have quite a bit of bottom time, and your tank tends to last a bit longer. There's also not the most abundant amount of sealife, compared to other locations, so if you just fly across the reef, you're bound to miss most of what makes the reef interesting. In conditions like this you will get the chance to discover that your tank lasts just fine when you relax and concentrate on 20 square feet of reef as opposed to trying to cover an entire acre. You'll learn to relax and take your time. And before long you'll realise that if you DON'T think about your breathing so much, you'll be relaxed and actually breathing less.

Practice and experience. Hang in there!

 

[soltari675]

Not sure how to get the decimals, but I calculated my SAC rate to 29 per minute. Not sure how good that is, however I am a very new diver. I am taking the peak buoyancy course this month to learn a little more and get better at it. I also have a bad habit from years of swimming on the surface of using my hands to turn and steady myself. I am sure I will stop that with time and experience. I focus on limiting how much I do that now. I have only done 15 dives though, so still so much to learn! What is the "ideal" sac rate? Mind you this is with an 80 AL tank in fresh water if it matters. Believe I used a cold night dive as well to calculate it. Kinda a worst case for me so far.


edit: Nevermind! Looked at my computer downloaded dive logs. Mine is 0.71 cf/min

 

[scubajim 1]

Sounds like you are off to a good start...and the advice so far is spot on!
I would suggest a Paek Preformance Bouyancy course. It will really help you decrease your gas consumption. It will go into weighting, trim, and swiming techniques that will all help you get more out of those 117s.
Enjoy yourself!

 

[knowone]

Everyone stops breathing between breathing cycles.

Do it for 3-5 seconds.

A quick inhale, is to avoid brushing or bumping into nice things
and not nice things, under or next to you.

A quick exhale, is for stopping going up, when you want to stay
where you are.

Cheap BCD.

Not for your Parents.

You MUST coordinate lungs with BCD.

Practicing in less than 20ft is frustrating for new to Scuba people and old to Scuba people.

 

[Dirty-Dog]

Being an air hog is fairly subjective. Along with all the other advise, consider your buddies. I have always considered myself to be an air hog (though "always" is a short time, with only 35 dives so far...) but when I actually checked, I found that my SAC rate runs from .5-.6, which is apparently not at all bad. So why do I seem to be an air hog? Because my wife is much smaller than me (I'm 6'1", 200lbs, she's 5'7", 125lbs) and the only other people I had to compare myself to were instructors. You know, people who have spent so much time diving that they've grown gills.
Relax and enjoy the time under water. Your SAC rate will take care of itself.

 

[TSandM]

soltari, there is no ideal SAC rate. A lot is going to be determined by your size. My dearest dive buddy is one of the most incredible stable, efficient, relaxed and beautiful divers you could ever hope to be in the water with, but his SAC rate runs twice mine. He's six feet tall and solid muscle, and I'm 5'4" and very small.

What you hope to do is become as efficient in the water as you can, and learn what YOUR gas consumption is under various circumstances -- what do you use on a mostly hovering drift dive, on a gentle swimming dive, or on a spearfishing dive (if you do that). Then you can use the number for planning. When we cave dive, we know how much gas we have to use, and each person can compare that to his known consumption, and come up with an idea of how long the dive should be before we turn. Comparing that information will let the leader know when to expect a signal from one of his teammates.

There is no "ideal". It's just information, useful for planning, and for comparing over time to see if you're improving.

 

[soltari675]

Thanks TSandM. That is helpful. I imagine I still have some dives to go before I get a solid idea on my usual consumption rate. I imagine it is a little high as I am 5'4" but over weight. (still in the gym working on that part). I am not out of shape too much though. So I will just keep an eye on it and judge it with time. Thanks again.