I have twenty dives under my belt now and am focusing on improving my air consumption. I am a fit 37 yr old male but can't seem to get more than 35 minutes on a max 60 fsw (warm, slight current) dive with an AL80 tank, while others are getting 45 minutes.
I have worked with divemasters on trimming my kit, adjusting weight and trying different fins. One suggestion I heard was that I am a big, athletic guy (6'2", 225lbs) and presumably have a big lung capacity, so am simply breathing more air from my tank per breath than others. This makes sense that if I take a deep breath I could be taking it a lot more air than, say, my wife (5'5", 120lbs). But then I see other big dudes getting more bottom time than me.
What gives? Am I destined to be an air hog? Should I be using a bigger steel tank to account for higher air volume needs?
Thanks for any feedback.
A lot of divers have been where you're at right now. The good news is ... it gets better.
When I started out, I'd suck an AL80 dry in 20 minutes ... and that on a shallow dive. Now I can get 75 to 80 minutes out of the same tank at the same dive sites. You get better with practice.
Here's an excerpt from a handout I use for a seminar I give ... maybe something in there will be helpful ...
Some tips for using your air more efficiently
Air consumption is often related to other aspects of your diving, such as buoyancy control, weighting, trim, your breathing pattern, and swimming speed. Once youve determined your air consumption rate, you should track it over a period of time and see if you notice how it changes over time. As overall skills improve, so will your air consumption
often dramatically.
Here are some tips that can help you improve your air consumption, and in general get more enjoyment out of your diving experience.
Breathing
Scuba diving presents most of us with the first time in our lives that we have ever actually had to think about breathing. For the most part, its something we just do and never give a whole lot of thought to. But underwater it affects us dramatically. And there is a technique to proper breathing on scuba gear. In general, you want to take long, slow, deep breaths. A complete inhale and exhale should take anywhere from 5 to 8 seconds
sometimes longer for more practiced divers. Rapid breathing affects our buoyancy
shallow breathing tends to build up carbon-dioxide in our body, which causes us to feel oxygen starved and breathe harder and faster. Practice long, slow, deep breathing on land
and then try it in the water. You will often notice an immediate improvement in your buoyancy control, and over time will notice that as your buoyancy control improves, so does your gas consumption.
Weighting
Improper weighting will affect your gas consumption considerably. Divers who are overweighted will go through their gas faster because they have to carry excessive gas in their BCD or wing to maintain neutral buoyancy, and even small changes in depth will cause excessive changes in their buoyancy because of the expansion or compression of that extra gas. You should perform weight checks any time you get a new piece of gear, and occasionally as your diving skills improve, because simply learning how to relax more underwater will often allow you to lose weights you thought you needed. Conversely, underweighted divers will struggle to stay down
working harder than they need to, which will also cause you to breathe harder than you should and consume your gas supply at a faster than needed rate.
Trim
Humans are psychologically oriented in a vertical position
its what weve done since we learned how to walk, and when learning scuba we must teach ourselves to move about in a horizontal position. Proper trim is very important to good gas consumption. Water is 800 times heavier than air, and we cannot efficiently move through water in the same way we move through air. Maintaining a horizontal position means that as we move through the water, we have to move less water out of our way than we would in a vertical position. It also radically increases the efficiency of our fins to move us in the direction we want to go. Both of those are huge factors in terms of our air consumption, because it reduces the amount of work we need to do to move about.
Swimming speed
Many divers, new divers in particular, tend to swim rather quickly. While that will get you from point to point faster, it will also increase your air consumption dramatically. In fact, the faster you go the more air you will consume getting from one place to another. Slow down
its not a race! There are lots of tiny creatures (and even some large ones that are good at camouflage) that you will miss if you speed by. Going slow, and keeping your fin kicks relatively small, will improve your air consumption dramatically.
I think at this point the best advice I can give you is to focus on these tips, and just worry about bottom time ... as you learn better form and relax a little your air consumption will take care of itself ...
... Bob (Grateful Diver)
