Tips on Lowering Air Consumption

[divingjd]

The other suggestions are all good. Remember that you want long, slow, deep breaths. In normal breathing, you breathe using only the top half of your lungs, taking relatively shallow breaths. The most efficient breathing pattern is long, slow, deep breaths. This is a little counter-intuitive and it is something you have to concentrate on to accomplish. Happily, this breathing pattern also relaxes you, helping to achieve one of the other goals. It is hard to over-emphasize the importance of being still. Keep your hands tucked in and spend a lot of time gliding instead of kicking constantly. It's like they told me when I took my first resort course. "Here in the islands we do things two ways: slow and deadly slow. In scuba, we do everything deadly slow."

 

[MXGratefulDiver]

I know none of you are suriprised to hear this, but on an aluminum 80 (the local shop fills to 2700 psi) at 30 feet, I am down to 500 psi in about 35 minutes. My dive instructor claims he can get 2 hours out of the same setup and the same conditions.

I suspect that much of his air supply is self-generated ...

Honestly, that's not the sort of thing an instructor should be saying to a student. Diving ain't a competition, and people who intentionally try to "stretch" their air supply will often only end up giving themselves a CO2 headache.

Like the others have said, diving more is the best way to reduce your air consumption. This is the first time in your life you actually have to think about breathing. Take the tips everyone has offered so far and apply them ... with dives, your air consumption will get better all by itself.

... Bob (Grateful Diver)

 

[ClayJar]

Let's see... 2700 to 500 psi, giving 2200 psi consumed from an AL80, which is nominally about 77.4 cubic feet when filled to 3000 psi. That gives 56.76 cubic feet consumed.

If he was on the surface at 1 ata and used that much air in two hours, that would make his breathing rate about 0.47 cubic feet per minute, which isn't at all unreasonable.

If he was at 33 fsw for two hours and used that much gas, that would make his adjusted surface breathing rate 0.24 cubic feet per minute, which would be more-or-less outstanding.

Going for the middle ground and assuming that with descents, terrain, ascents, and stops, he'd average 20 fsw (2/3 of his max depth) over the course of the two hour dive, he'd end up with an adjusted surface breathing rate of 0.29 cubic feet per minute, which would be really nice if I had it.

(If you assume he exaggerated slightly over the numbers, and actually had, say, a 3200 psi overfill, averaged only 20 fsw, and finished around 110 minutes, you start getting a little closer to *my* numbers on a rather good day. )


When I started, I didn't hoover my tanks down, but I used air at a good clip. In the many, many dives since then, I've become proficient at buoyancy and trim, I've dropped all but three pounds of weight (when diving a neutral-at-empty tank), I've become one with the frog kick, and I've become completely at home in the water. None of those changes stuck out as exceptionally significant in my logbook (I calculate my surface-adjusted cubic feet per minute rates on every dive), but put together over, say, 50 dives, I can certainly see the difference. I easily use 50% less air than I did in my first dives.

One of the most interesting things I've found is that I'm often wrong regarding my impression of whether I'm sipping or hoovering. I have no problems estimating air time remaining, gas needed for ascents and stops, or what have you, but sometimes I feel like I must have been absolutely burning through my tank. Then, when I do the numbers in my logbook, I find out that I was actually within a percent or two of normal, and sometimes lower than the last dive (where I felt like I was positively sipping air). Having a computer (wrist computer, not air integrated) to tell me my average depth so I can run accurate surface-adjusted air consumption numbers every dive has really helped me understand my air consumption, both in how conditions affect it as well as how sometimes my gut feelings can be quite undependable.

 

[Nut Bubblefish]

To summarize all that was said and that I agree with:
dive more
be trim
stay still
don't use your arms
fin slowly, or even do not fin, unless you really have to
be properly weighed
breathe slowly (like just before you fall asleep)

I would add: be fit. Loose few kilos if you have more than enough, and exercise regularly (jogging, swimming, finning, whatever...)

And who cares if the instructor can last 2 hours? you are not supposed to dive more than 60 minutes, are you?

 

[ReefHound]

Amid all this excellent advice to slow down your breathing it's important that you not fall into the trap of breathing shallow. If you breath shallow you will not vent your lungs properly and will build up CO2, leading to the desperation feeling that you are suffocating. You will also adjust your buoyancy to low lung volume so when you finally do breath in deeply you'll start rising up too much.

 

[LavaSurfer]

And who cares if the instructor can last 2 hours? you are not supposed to dive more than 60 minutes, are you?

Good point on the first question
Why? on the second. What rule or table are you using?

Here is a great web site that talks about ways to breath and reduce your SAC
http://www.neptunediveandski.com/breathing.htm

I found it useful!

 

[ReefHound]

And who cares if the instructor can last 2 hours? you are not supposed to dive more than 60 minutes, are you?

What do you mean by this???

 

[LavaSurfer]

And who cares if the instructor can last 2 hours? you are not supposed to dive more than 60 minutes, are you?

Good point on the first question
Why? on the second. What rule or table are you using?

Here is a great web site that talks about ways to breath and reduce your SAC
http://www.neptunediveandski.com/breathing.htm

I found it useful!

 

[HowardE]

Hi All,

I am a new diver (a dozen logged dives), and I tend to go through my air pretty quickly. I know none of you are suriprised to hear this, but on an aluminum 80 (the local shop fills to 2700 psi) at 30 feet, I am down to 500 psi in about 35 minutes. My dive instructor claims he can get 2 hours out of the same setup and the same conditions. I have no idea if he is full of it or not, but I am wondering if any of you have any tips for me. Here is some other info about me:

I believe that I am properly weighted
I don't have hoses dangling everywhere
I am not nervous underwater, and I feel pretty relaxed

Thanks for the help!

Honestly - the best advice to improve your consumption is -

Go somewhere for a week of diving ... Cozumel, Roatan, Bonaire... whatever. Dive like 3 or 4 times a day for a week, and your consumption will be much better.

Don't try any "tricks" and you don't need to work on every little thing. Consuming less air just comes with experience. The more you dive, the slower you'll breathe. Even though you THINK you're relaxed... After you do like 50 dives or so, you'll see what relaxed really is

Soon (after you gain more experience) you'll find that your SAC has improved greatly, and you're not even THINKING about breathing.

Your instructor is really doing you a dis-service, with his/her apparent mockery of your consumption.

 

[pwl]

my original instructor likened scuba to "underwater yoga" .

one key thing i didn't come to grips for a while was that although i was exhaling slowly, i was inhaling fairly quickly. slowing down inhaling helped relax me & get into the yoga-like "zone"

30-40 minutes @ 10m seems about normal for the new students i've seen. a lot in particular have trouble at the end of the dive when the tank gets empty & light & they pop up to the surface. they might have a fair amount of air in the tank still but haven't got the knack of staying down yet.

practice will help, mainly - try to dive as frequently as you can & you'll get a good technique in no time. that first 1-hour-plus dive time is a blast