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
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!
I got the idea reading
about how important visualization is to sports psychology, and it really
seemed to make a difference for me.
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
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
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
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.
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
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
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!
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?
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.
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.
All material © 2001-2006, Robert W. Warfield.