10 Steps to Better Air Consumption
   

 

"Hi. My name is Bob, and I used to breath too much air."

Here is something interesting to ponder:

Despite the fact that it contains more oxygen, Nitrox does not reduce most people's air consumption. Come to think of it, as we learned in our diving classes, we are consuming more oxygen at depth because it is delivered to us at a higher rate. How is it that we can be getting more oxygen but not feeling less need to breath?

 

Understanding this puzzle is the key to lowering your air consumption. The answer is in two parts. First, due to a peculiar wrinkle in how evolution has wired our bodies, the need to breath is triggered not by too little oxygen, but by too much carbon dioxide. If you have no exposure to carbon dioxide whatsoever, or if you can get rid of your carbon dioxide before it triggers the need, you will not feel a need to breath even when oxygen levels get dangerously low. Hyperventilating before free diving is really aimed at getting rid of carbon dioxide more then "hyper-oxygenating" the blood. It takes away the feeling of needing to breath without really expanding the true oxygen capacity available all that much. This is one reason it can cause you to black out without having felt the need to breath.

But how is carbon dioxide produced? Through stress, motion, and metabolism. Reduce any of those and we do better.

This idea of feeling a need to breath exposes the other half of the puzzle. That half is psychological or behavior based. The good news is that it is a big part--you really can make a big difference even if you are a big burly guy who ought to need a lot of oxygen. Some of what I'm going to tell you is aimed at the psychology of air consumption and some is aimed at the carbon dioxide side of the equation. Add it all up and you can make great strides.

1. Bigger Tanks

Don't laugh-this works if you are diving in a situation where you can bring your own tanks. I do a lot of diving in the Monterrey/Carmel area and was really tired of always being the guy who called the turnaround to shore. I just couldn't last long with an aluminum 80 when I first started to dive.

My solution was to go to my local dive shop and purchase 120 cubic foot high pressure steel tanks. These tanks require DIN fittings, but you can fill to almost 4000 psi. A 120HP tank with a 3900 fill has almost exactly 2 times as much air in it as an aluminum 80 filled to 2800 pounds. That will cure a lot of air consumption woes!

Surprisingly, the tank does not seem painfully heavier or larger to deal with, though it is definitely bigger. We weighed it at the shop on a bathroom scale and it was 5 pounds more than an aluminum 80. Better to take 5 pounds off the weight belt and use it to carry more air, right? I figure its better having too much than too little where air is concerned. Well worth the investment. I also have a couple of 100HP tanks that are a little smaller and still carry quite a bit more air than the aluminum 80's.

2. Be Warm Enough

As I said above, I do a lot of diving in the cold waters of Northern California. Being warm enough is critical to being able to dive at all here. But I have seen divers get cold in tropical waters too. If you are cold, your air consumption is going to go up because you feel stress, and because your body cranks up metabolism to preserve core temperature. Shivering is the ultimate metabolic crank up tactic the body will use. Make sure you have adequate protection from cold and you'll be much better off. Don't assume this doesn't apply to you because you don't feel cold either. I never felt cold in a 6mm wet suit diving in 50 degree water, but I was so much more comfortable in my dry suit that my consumption went down noticeably.

There is a peculiar exception to this rule. It's called the "diver's reflex". It seems that exposing the face to cold water will actually signal the body to slow its metabolism and oxygen requirements. This is a built-in defense mechanism against drowning that is common to mammals, and is extremely well developed among marine mammals. We don't fully understand how it works, but we do trust that it does work. I have seen a number of experienced divers who swear by it. They get in the water sans mask and dunk their face directly into it to start up the reflex before they submerge. I think it's worth a try, but haven't experimented with it too much.

3. Visualize Calm

Diving can be very stressful, particularly if conditions are a little rough and you are new to the sport. I got my start diving from the beach in Northern California. It's cold, there is considerable surf with frequent surge underneath, and visibility is low. This can be stressful!
Any form of stress is going to damage your air consumption. I got into the habit of visualizing my entry to the water as a calming event. I would simply picture the cool water as being refreshing and relaxing. I did this before getting in, and continued to concentrate on the thought until I was completely calm in the water. Rather than worrying about gearing up for a dive, my thinking was on how nice it was going to be to get into the refreshing cool water.

I got the idea reading about how important visualization is to sports psychology, and it really seemed to make a difference for me.

4. Breathing

How does one breath in order to minimize consumption? I'm sure you've heard the admonitions against holding your breath or skip breathing. I focus on exactly the same type of breathing as is taught in stress management classes. The idea is to inhale slowly until you can inhale anymore, and then exhale slowly until you can't exhale anymore. Between whatever stress reduction this yields, and just creating a little slower rhythm it seems to work extremely well.

One thing that takes a little experience to overcome is the feeling that you never want to let your lungs get completely empty-you might need that extra breath if you have an equipment failure of some kind. But the extra breath is there automatically, if you rise, the air in your lungs will expand. Even if you empty your lungs as much as possible, unless you are very deep, the expansion happens pretty quickly too. So don't try to breath "on top of" a breath you are holding. Long inhale, long exhale gets the job done efficiently, and also leaves you feeling very satisfied for air.

5. Integrated Air Computer

There's nothing like keeping score if you want to get better at something. Integrated air computers simply automate the task of keeping score. Instead of looking at a crude analog gauge reading pounds of pressure, you get a constant readout of minutes of air remaining. You can literally change your behavior minute to minute and see what effect it's having on your consumption. You can also use this tool to pace yourself on a dive. I try to shoot for somewhere between 45 and 60 minutes underwater, depending on the depth. If I see I'm falling a bit shy of that goal, I will take steps to reduce my consumption.

6. Motion and Planning Ahead

All motion initiated by the diver, in other words motion other than current or buoyancy induced, requires muscles to move. Those muscles consume oxygen and produce carbon dioxide. This increases our need for air.
It is amazing how much difference you can make in air consumption by eliminating unnecessary motion. Think ahead and plan your path through the reef. Don't just move around randomly--be systematic and efficient. Don't bounce back and forth all over the reef just because others have found something. Figure out who in the group is best at finding things and follow them as economically as possible, or do your own looking. Unless it's a really spectacular find, it usually isn't worth it to cover all the ground needed to go see every little thing that has divers clustered up over a hole.

This is especially critical in drift diving. Position yourself towards the rear, so you have plenty of warning of something to look at. Use the current to your advantage.

Above all else, move slowly. Drag goes up as the square of velocity. It takes 4 times as much effort to overcome the drag of moving twice as fast. All the best divers will be seen moving slowly and economically. Besides air consumption, the other bonus is that it scares the fish less than thrashing around, so you will see more interesting things.

While we're on the motion thing, buy a set of split fins. One magazine determined that they are 40% more efficient in terms of air consumption than other fins. That is huge!

7. Buoyancy Control

Proper buoyancy control is essential to good air consumption. An obvious conclusion is that if you are constantly adding and then dumping air from your BC that you are using air that could have been breathed.

I've seen some experienced divers who are so stingy with air that they never use the inflator. If they want more air in the BC, they will put it there by exhaling into the BC, just like your training for manual inflation. I am not a big believer in this practice for two reasons. One, I waste some air purging the regulator each time-chalk that up to my own ineptitude. An expert in technique will save enough of the exhaled air on each breath to do the purge, so it just may take a couple of puffs on the manual inflator mouthpiece to get the job done. A more compelling reason can be had by anyone who wants to try blowing a good breath of air into the BC. What I've found is that it is usually considerably more air than I get out of my fine adjustments with the inflator button. In short, there just isn't that much air involved inflating the BC and it's all too easy to lose the same amount or more purging the reg.

There's a different theory for why this is so important to good air consumption. This theory says you exert yourself a lot more swimming if you aren't neutral.

Recall our discussion of motion. If we are neutrally buoyant, it requires no work to maintain depth. We are neither kicking downwards to offset too much buoyancy, nor are we kicking upward to offset negative buoyancy. Next time you are with a group, watch how many divers swim slightly head up. This is because most people are inherently more comfortable with a little bit of negative buoyancy. They expect to sink slowly if they just quit swimming. They want the security of feeling firmly anchored on the bottom when they dump the BC. But I say that you haven't really experienced diving as it ought to be until you have been truly neutral.

So what is "truly neutral"? If I exhale, I sink, albeit slowly. If I inhale, I rise, again slowly. If I dump my BC, I am floating with water at about eye level, and I have to flip over and give a couple of kicks to start descending. This last simply uses water pressure to force residual buoyant pockets to flatten. Next time you dive, dump all your air and go to the bottom. Are you sitting on the bottom pretty hard, or do you feel a tendency to float up with each current or breath? The latter is how it's supposed to be.

7. Depth

As we all learned during certification, going deeper means we consume more air. It has to be pumped out of the tank at a higher pressure to overcome water pressure, so you will consume more. It seems pretty obvious that you don't want to go any deeper than you have to in order to see what's cool.

So, rather than having the deepest number of your dive computer at the end of a dive, you want the longest time. It's a better test of manhood!
How to accomplish this? First, there is common sense and planning ahead. But here's an even easier tip. If you are diving with a group, why go any deeper than the leader? They're the expert on the region, it will be very rare that you see something they don't, so there is little advantage in going deeper. It makes them nervous every time you do it anyway. Keep an eye on them. I think you'll notice they're doing some pretty shrewd moves almost automatically.

In Cozumel, one frequently travels over sand a bit to get to the next reef. I noticed the divemasters all rose up in the water column 20 to 30 feet. There was nothing to see between reefs, so why drag along the bottom in the sand?
When exploring a reef, you can swim along the edge near the bottom, or along the top. The top means lower air consumption. Train yourself to use these tactics automatically and you'll cut your consumption for sure.

8. Easy Breathing Regulator

I use Scubapro's top of the line regulator, and I have tried a number of other regulators as well. For example, I have a Nira regulator in my Ocean Reef full face mask. There is a noticeable difference in the breathing effort among various regulators. When properly adjusted to my liking, the Scubapro exhibits almost no effort at all. There is no sensation of "sucking" on the reg, and no sudden "cracking open" for the release of air. In other words, it feels very natural. The Sea Cure mouthpiece I have added further maximized that natural feeling.

I find that maximizing the naturalness helps make it easier to focus on the breathing style I use and contributes to reducing my consumption.

10. Experience

If you take advantage of all of these things as a new diver you will reduce your air consumption. But the most important component of all is experience. Experience comes in two forms. First is total number of dives. But there is a shelf life to experience, and the second form is in the length of time since you last dove. My consumption drops rapidly during the first 3 dives of a dive vacation. It isn't usually until the second dive on the second day that I get to what I consider my normal consumption. So keep that in mind. Do more dives, and try to stay current.

To give you some idea of how well this can work, I typically dive for 45 to 60 minutes depending on maximum depth, and when I surface I will have 1000 to 1200 pounds of air left in my aluminum 80 tank. That works for me. I get the reputation of being first one in and last one out with the divemasters.

Relax and take a deep breath...

 
All material 2001-2006, Robert W. Warfield.