Need advice about how to use less air

[Jenipher]

I am new to Scubaboard and have been diving 6 years. I need advice on how to use less air. Does height have anything to do with the amount of air I use? Thanks!!

 

[ScubaSteve]

First of all, stop worrying about it. The more you focus on it the more air you will go through. This I know because I was there 6 years ago.

The biggest factor beyond lung capacity is your weighting (trim and buoyancy). Take every pound off your belt that you can while still being able to safely ascend on an almost empty tank (you should know how to check for proper weighting). From there, distribute your weight around so that you have good horizontal trim. Remember that the more vertical you are, the more energy you need to use to propel yourself through the water.

When was the last time you checked your weighting?

FYI, I have found it to be a great advantage having people video me so that I can actually see my trim and buoyancy among other things.

 

[Jenipher]

I dove two weeks ago and had to add two pounds to descend easily, I know my buoyancy was good after that. Most of my dive buddies are alot shorter than I am and use less air. Could that be a contributor? Just looking for an excuse

 

[ScubaSteve]

I am 6'2" and big framed (including a bit overweight) and I can pretty much keep up with many of my dive buddys who are much smaller than me (some are petite women). So, yes it can contribute, but that does not guarantee that you cannot improve.

At 25-49 dives, it is very possible that you may still be overweighted. Just because you feel like you were properly weight underwater does not mean that you were. It just means that you added enough air to your BC to compensate for the weight.....which is another thing that hurts your SAC.

You should be able to float at eye level with an empty tank on (500psi) and absolutely no air in your BC. That is how you determine proper weighting. You really should do that after your next dive because you might be surprised. IIRC I dropped about 14 pounds off my belt in the first 50 dives of mine. You will likely be very surprised at how much extra weight your are carrying.

 

[Jim Lapenta]

If you are really using air fast there could be any number of reasons from working too hard during dives to not diving enough. If you are chasing after buddies all the time then they are swimming too fast. If you are always waiting for a buddy to catch up then you are going too fast. Either situation will result in increased consumption.

Steve's advice regarding a proper weight check is another very good point. New, newer, or inexperienced divers are often overweighted. While not new 25-49 dives in 6 years is not very many and this could be a big factor. How often are you able to get in the pool with gear? I did not do as many dives last year as I would have liked- only about 40- due to my late wife's illness. But I had over 50 hours in the pool with students and just messing around. I have 60 so far this year and 20 dives in. I'll be very close to 100 for this year. Checkouts coming and fun stuff after that.

The more you dive the more relaxed and comfortable you will be. That will result in less air used.

 

[carrielsal]

One of the things I did when I was trying to lower my air consumption was count as I exhaled. I started with exhaling to a 3 count and increasing the length of my exhalation over time.
I also had a computer with tranmitter that would calculate my air consumption. I could look at my dives over time and could see patterns. When I dive with my regular buddy, my air consumption would be a lot less then if I was diving with someone new. I could also see how equipment changes, water temps, etc. affected my air consumption.

 

[Starcruiser]

Scubasteve had a great point... stop worrying about it. I was an air sucking pig for the first two or three years after I started diving regularly. I found that the more frequently I dove, the more confident I became that I could trust my self and my equipment to get me through the dives. As I relaxed, my air consumption went way down. Also ditto on the proper weighting. Relax, enjoy the sport, and it will come.

 

[Brandon]

Dive more.

-B

 

[TSandM]

As a general rule of thumb, larger people will use more gas than smaller people, simply because they have more mass of tissue to use oxygen and generate carbon dioxide. That's also dependent on fitness level, however. But in diving, most of gas usage differences are due to technique. Here is a little essay I wrote some time ago on the topic:

This is a very common problem for new divers!

There are really two answers to this question, and they are interrelated. One is relaxation, and the other is efficiency.

When you are a new diver, the very mechanics of being underwater and managing your buoyancy, navigation, and all your equipment use up a lot of bandwidth, and very new divers are rarely completely relaxed. Tension causes you to breathe inefficiently, keeping your lungs fairly full and just exchanging a small amount of gas with each breath (this contributes to the difficulties with buoyancy that new divers have, too!) Because a large part of each breath is only ventilating the trachea and major bronchi, structures which do not participate in gas exchange, a lot of the breath is wasted as far as getting oxygen into the bloodstream and CO2 out are concerned. Therefore, you have to breathe at a higher rate, wasting a lot of your consumed gas into the water.

But a major thing that contributes to tension, and massively contributes to gas utilization, is inefficiency. What do new divers do that's inefficient?

To begin with, they often do not have their equipment properly balanced. Especially when diving in cold water, where a lot of weight is necessary, it's important to distribute that weight so that the diver in a horizontal position will tend to REMAIN in a horizontal position. If you are carrying a lot of weight low on your body, as the integrated weight pouches of many BCs will place it, then you will always tend to float in a feet-down position. Once you think about it, it becomes pretty obvious that, if you are feet down, every kick drives you UPWARD. In order to stay at the same depth, the diver has to keep himself negative, so the upward drive of the fins is countered by the sinking created by the negative buoyancy. What that means is that a good portion of the effort expended in every kick results in no net motion at all! Since muscle activity uses more oxygen and creates more CO2, this means that all that useless motion is sucking gas out of your tank.

In addition, because of the lack of balance, new divers often swim with their hands. The hands are not an efficient means of propulsion underwater, especially not compared with fins, so again, this is largely wasted motion.

When you are not balanced so that you can remain still, you must swim constantly. I can remember my own beginning days -- it irritated the daylights out of me that my buddies could simply STOP and look at something, when I would have to swim circles around them, because I simply couldn't be still. Achieving a good, flat body posture and balancing my equipment allowed me to learn just to hang in the water, which is not only a great way to look at things, but is great fun in its own right.

Achieving good buoyancy control, which includes getting properly weighted, helps with gas consumption as well. You probably learned during OW that you could affect your buoyancy with your breath. This is very true, but if you overuse this mechanism, you waste a lot of gas (not to mention setting yourself up for a CO2 headache). In the beginning, when you aren't quick to detect changes in depth, and when you are perhaps not as judicious in adding and venting air from your BC, you will make many buoyancy adjustments, both with the BC and your breath. As you gain experience, you will learn how to anticipate the need to change buoyancy, and you'll learn to add or vent air in very small amounts, keeping your buoyancy from ever being far from neutral. Gas consumption will go down with this facility, as well.

Finally, there is a level of gas consumption that will be required by your body and your degree of fitness. My favorite dive buddy is one of the most beautiful divers you could hope to see -- He is relaxed, extremely still in the water, and VERY skilled with his buoyancy. But his gas consumption is almost twice mine, simply because he's about twice my size. It would be absolutely counterproductive for him to work on his gas consumption as an end in itself; we simply dive different sized tanks, and life is good for both of us.

Have fun with this, and don't get anxious about it. Do, if you can, spend some time in a pool working with the trim pockets on your BC, or some weight pouches on your cambands, and try to get your rig balanced so you can hover in a horizontal position. This will result in a very big reduction in your gas needs.

 

[The Kraken]

Streamline. Breathe slowly and deeply. Relax.

That being said, the individual requirement to fill one's lungs (tidal capacity) varies from one person to another. The larger the person, all other things being equal, the greater volume required to fill the lungs (tidal volume).

If we all were to dive together and all of our senses were equally tuned and normalized there would still be those who require more gas simply because it takes more gas to fill the lungs. It's a fact of individual physical configuration.

Don't worry about it. Dive. Relax. All things will come in time.

the K