18 Ways To Use Less Air
by Selene Yeager
Use these secrets of the air-sippers to stretch your next tank.
Do you consistently run through your gas supply faster than other divers on the boat? Do
you frequently have to end the dive before the rest of the group? What's going on? And what
can you do about it?
First, you can stop beating yourself up over it. People are different. Those with slower
metabolisms will--other factors being equal--use less oxygen. Small divers have to use
less energy than big ones to swim forward, so they also use less oxygen. Nature doesn't
distribute her gifts equally, and you may never be the stingiest sipper of gas on the boat.
On the other hand, most of us can reduce our gas consumption and thereby extend our
dives. We can be better, even if we can't be the best. Typically, divers waste air in one or
more of these three ways:
By leaking it before it gets to their lungs, thanks to free-flowing octos and worn out O-rings.
By using more energy than necessary. Using energy means using air, because oxygen is
necessary to burn the calories that make energy. Every bit of unnecessary exertion costs
you psi.
By getting less than maximum benefit from each breath. When divers breathe inefficiently,
they exchange less oxygen for carbon dioxide with each breath, so they need to take
another breath sooner.
Here are 18 tank-stretchers to try, starting with the obvious first step.
Fix the Small Leaks
Even a tiny stream of bubbles from an O-ring or an inflator swivel adds up over 40 minutes,
and may be a sign of more serious trouble ahead anyway. You don't think you have leaks?
Do you have eyes in the back of your head? Ask your buddy to look behind you to be sure. A
mask that doesn't seal is another kind of leak in that you have to constantly blow air into it to
clear out the water. It's also a source of stress, which needlessly elevates your breathing
rate and thereby reduces your breathing efficiency. Does your octo free-flow easily? That
can dump a lot of air quickly. Detune it or mount it carefully so the mouthpiece points
downward.
Dive More
Inexperienced divers are famous for burning through their air supply at a furious rate. The
reason is anxiety. A new diver is understandably nervous, and his body's automatic
response to danger is to raise his metabolism, his heart rate and his breathing rate. It's
hard-wired, the body revving its engine to be ready for fight or flight, though the result is a lot
of air cycled through his lungs but never used, just dumped into the ocean.
You may not be a new diver, but unless you dive almost every week it's still an unnatural
activity, and your body isn't as happy as you are about putting its head under water. Dive
more--your body will get used to the idea, and you'll breathe less.
Take a Class
Any class, almost, will reduce your gas consumption just by making you feel more
accomplished and therefore more comfortable. But the best bet is probably a class to
improve your weighting and buoyancy control. When you get that dialed in, you can control
your altitude mostly with your lungs, so you're not squirting that valuable gas into your BC
and then venting it to the ocean. Most important, you can now forget (nearly) about the
mechanics of diving, drift like a fish, and relax.
Sleep More, Party Less
Be well rested on dive day. Fatigue is stress. If you start the dive already tired, your body
has to work harder to overcome the extra burden, so you breathe harder. A hangover is
stress too. You may think you're sober in the morning, but in fact alcohol and other drugs
affect your physiology the next day. As SSI instructor Jim Bruning puts it, "Your body does
what your mind tells it to. If you had a good night of sleep, your body and mind are going to
be much more relaxed, much calmer."
Be Early
If you're late to the boat, running to get your gear on board, worried about the hard looks of
divers who were on time, stuck with the least-convenient gear station and generally playing
catch-up all day, you're giving yourself unnecessary fatigue and mental stress. You start the
day breathing hard and never have a chance to calm down. On the other hand, if you're early
to the boat, early to gear up and early to the dive briefing, you'll conserve your energy, feel
confident and relaxed, and your breathing will remain slower.
Swim Slowly
The energy cost of speed is even more than you might think because it's an exponential
function proportional to the square of the speed. So swimming twice as fast requires four
times as much energy and air. But the reverse is true, too: Swim half as fast as you do now,
and you'll use only one-fourth as much air.
Stay Shallow
It's physics again. Because your regulator has to deliver air at the same pressure as the
water, a lungful at 33 feet (two atmospheres) takes twice as much out of your tank as does
the same breath at the surface. At 99 feet (four atmospheres) it takes twice as much as at
33 feet.
There's absolutely nothing you can do about that except to avoid being deeper than you
have to be. If you're making a transit over an uninteresting sand flat to get to the edge of the
drop-off, do it at 15 feet instead of at 40 feet, and you'll save air.
Minimize the Lead
If you're overweighted, you have to put more air into your BC to float it and be neutral. The
inflated BC is larger and requires more energy and oxygen to push it through the water.
An extra eight pounds of lead means your BC is one gallon bigger when inflated enough to
make you neutral. Imagine the extra effort of having to push a gallon-sized water jug
through the water.
Adjust Your Trim
If your body is horizontal in the water, when you swim forward, your legs and fins will pass
through the "hole" in the water made by your head and shoulders. You'll disturb less water
and expend less energy and air.
Many divers, however, swim with their feet lower than their torso and their head higher.
Adjust your trim by moving some lead from your hips to your back--to trim pockets on your
BC or to your tank.
Seek Neutral Buoyancy
Always being exactly neutral is the key. If you're not, if you're slightly heavy or light, you're
constantly using fin power (and air) to maintain a constant depth. If you're not neutral, you
can't glide between fin strokes and you can't hang effortlessly.
Streamline Your Gear
All fast-swimming fish have smooth skins with few or no protuberances. That minimizes
drag so they can swim with the least energy and oxygen consumption. Divers, by contrast,
have rough, convoluted surfaces with all sorts of attachments from scuba tanks to whistles.
Anything disturbing the flow of water past your body creates drag and wastes air.
Do your best to imitate the fish. If you don't need a light on this dive, for example, don't take
it. If you do need something, try to hide it in a pocket instead of dangling it from a D-ring.
Take the snorkel off your mask and strap it to your leg or tuck it under your BC or get a
folding snorkel that fits into a pocket. Shorten hoses that are too long. Clip your console
close to your body. Suit your gear to conditions: You don't need the bulk of a BC with 40
pounds of lift in the tropics.
Streamline Your Movements
Keep your arms close to your body. Straighten your legs and keep them as close together
as your fins will allow. Kick with short strokes so your fins stay within the slipstream of your
body. Some fins do require a wider stroke so you have to compromise between efficient
propulsion and streamlining. But usually you're better off finning faster instead of wider.
Breathe Deeply
Any oxygen taken from your tank but not absorbed into your bloodstream is wasted. That's
the case when you take short, shallow breaths. A large part of the air you take in fills your
throat and bronchia, but doesn't reach your lungs before it is expelled again. You have to
take another shallow breath sooner because you didn't get much benefit from the first one,
and a lot of air is wasted.
Instead, try to inhale deeply, filling your lungs completely with each breath. A deeper breath
brings air to more of your lungs' tiny "air sacs" (the alveoli) where gas exchange takes
place. It also adds more fresh air to the volume of "dead air" that remains in your lungs,
throat and mouth from the previous breath, so the mix is richer. When more alveoli are
more fully inflated with fresher air, gas exchange is more efficient: More oxygen is extracted
from the incoming air and more carbon dioxide is released. Although each breath uses
more air, you will take fewer breaths, and the net effect will be that less air is used. Short,
shallow breaths are more frequent and less efficient.
Exhale fully too, so you expel as much carbon dioxide as possible. Anything not exhaled is
carbon-dioxide-heavy "dead" air. On your next inhale, that dead air--instead of fresh
air--partially fills your lungs. The urge to take the next breath is triggered not by lack of
oxygen but by excess of carbon dioxide, so you find yourself inhaling again sooner. On the
other hand, a deep exhale extends the time before you feel the need for another breath.
Breathe Slowly
You consume considerable energy just by breathing, by sucking the air in and pushing it
out again. To inhale, you have to suck open a demand valve in your second stage and pull
gas down your throat and into your lungs. Each inch along the way and each corner the gas
stream turns mean friction and turbulence. Both increase the effort you put out in just
breathing and decrease the amount of gas that actually gets to your lungs. Friction and
turbulence are unavoidable, but the amount goes up dramatically when you try to breathe
quickly--just as a faster-moving boat creates a bigger wake. The problem gets worse as
you go deeper because the gas is thicker--it's like trying to suck a milkshake instead of
water through a straw.
So don't force it. Try for a long, slow inhale until your lungs are full, then a long, slow exhale
until they are empty. More air will get to your lungs, it will spend more time there exchanging
"good" for "bad," and you will use less energy pushing the air back and forth.
Upgrade Your Gear
Overhaul your regulator on schedule and consider one with lower work of breathing,
especially if you often dive deep. ScubaLab tests have shown that the work of breathing
demanded by some regs can be three times as much as others, even more. A
"hard-breathing" reg not only demands more energy and therefore oxygen just to operate it,
your difficulty breathing through it increases your anxiety level and elevates your breathing
rate. So it wastes gas two ways.
Get in Shape
Two people climb a flight of stairs. At the top, one is huffing and puffing and the other is
breathing normally. The heavy breather is getting more oxygen, but he's wasting a lot of
what he inhales because he's breathing so rapidly there isn't much time for gas exchange.
It's an adaptation that makes sense only on land where the air supply is unlimited.
Diving can be surprisingly strenuous because water is so much denser than air.
Swimming into a current, it's not difficult to elevate your breathing to the very wasteful rate of
huffing and puffing. But even much lower levels of exertion will cause your breathing rate to
rise. How much it rises and how soon depend mostly on your aerobic conditioning. A diver
in better condition will have less increase when the workload goes up, so he will use less
air. The other part of getting in shape is to lose fat and achieve a more streamlined shape.
Stay Warm
Even warm water is cold when you're immersed in it, because if it's cooler than about 95
degrees, it takes heat out of your body at a surprising rate. Heat is energy that has to be
replaced by metabolism, using oxygen to make it. Getting cold also creates mental stress
which, often without your noticing it, increases your breathing rate.
And Just Chill Out
The competition over who uses less air can itself be a problem when divers associate low
gas consumption with diving skill, virtue and the right to take up space on the boat. It's one
of those self-fulfilling prophecies: You worry about using more air than your buddy, which
causes stress, which elevates your breathing so you do, in fact, use more air.
In fact, a higher rate of air consumption can be caused by many things, some of them
fixable and some not. In itself it means little or nothing and is nobody's business but yours
and arguably your buddy's--who, we hope, is not out to ruin your day. So if you'd like to
reduce your gas consumption, work gradually on reducing your lead, controlling your
buoyancy, improving your shape and posture in the water, going slowly, breathing slowly
and relaxing. Then forget about it. That alone will help.
by Selene Yeager
Use these secrets of the air-sippers to stretch your next tank.
Do you consistently run through your gas supply faster than other divers on the boat? Do
you frequently have to end the dive before the rest of the group? What's going on? And what
can you do about it?
First, you can stop beating yourself up over it. People are different. Those with slower
metabolisms will--other factors being equal--use less oxygen. Small divers have to use
less energy than big ones to swim forward, so they also use less oxygen. Nature doesn't
distribute her gifts equally, and you may never be the stingiest sipper of gas on the boat.
On the other hand, most of us can reduce our gas consumption and thereby extend our
dives. We can be better, even if we can't be the best. Typically, divers waste air in one or
more of these three ways:
By leaking it before it gets to their lungs, thanks to free-flowing octos and worn out O-rings.
By using more energy than necessary. Using energy means using air, because oxygen is
necessary to burn the calories that make energy. Every bit of unnecessary exertion costs
you psi.
By getting less than maximum benefit from each breath. When divers breathe inefficiently,
they exchange less oxygen for carbon dioxide with each breath, so they need to take
another breath sooner.
Here are 18 tank-stretchers to try, starting with the obvious first step.
Fix the Small Leaks
Even a tiny stream of bubbles from an O-ring or an inflator swivel adds up over 40 minutes,
and may be a sign of more serious trouble ahead anyway. You don't think you have leaks?
Do you have eyes in the back of your head? Ask your buddy to look behind you to be sure. A
mask that doesn't seal is another kind of leak in that you have to constantly blow air into it to
clear out the water. It's also a source of stress, which needlessly elevates your breathing
rate and thereby reduces your breathing efficiency. Does your octo free-flow easily? That
can dump a lot of air quickly. Detune it or mount it carefully so the mouthpiece points
downward.
Dive More
Inexperienced divers are famous for burning through their air supply at a furious rate. The
reason is anxiety. A new diver is understandably nervous, and his body's automatic
response to danger is to raise his metabolism, his heart rate and his breathing rate. It's
hard-wired, the body revving its engine to be ready for fight or flight, though the result is a lot
of air cycled through his lungs but never used, just dumped into the ocean.
You may not be a new diver, but unless you dive almost every week it's still an unnatural
activity, and your body isn't as happy as you are about putting its head under water. Dive
more--your body will get used to the idea, and you'll breathe less.
Take a Class
Any class, almost, will reduce your gas consumption just by making you feel more
accomplished and therefore more comfortable. But the best bet is probably a class to
improve your weighting and buoyancy control. When you get that dialed in, you can control
your altitude mostly with your lungs, so you're not squirting that valuable gas into your BC
and then venting it to the ocean. Most important, you can now forget (nearly) about the
mechanics of diving, drift like a fish, and relax.
Sleep More, Party Less
Be well rested on dive day. Fatigue is stress. If you start the dive already tired, your body
has to work harder to overcome the extra burden, so you breathe harder. A hangover is
stress too. You may think you're sober in the morning, but in fact alcohol and other drugs
affect your physiology the next day. As SSI instructor Jim Bruning puts it, "Your body does
what your mind tells it to. If you had a good night of sleep, your body and mind are going to
be much more relaxed, much calmer."
Be Early
If you're late to the boat, running to get your gear on board, worried about the hard looks of
divers who were on time, stuck with the least-convenient gear station and generally playing
catch-up all day, you're giving yourself unnecessary fatigue and mental stress. You start the
day breathing hard and never have a chance to calm down. On the other hand, if you're early
to the boat, early to gear up and early to the dive briefing, you'll conserve your energy, feel
confident and relaxed, and your breathing will remain slower.
Swim Slowly
The energy cost of speed is even more than you might think because it's an exponential
function proportional to the square of the speed. So swimming twice as fast requires four
times as much energy and air. But the reverse is true, too: Swim half as fast as you do now,
and you'll use only one-fourth as much air.
Stay Shallow
It's physics again. Because your regulator has to deliver air at the same pressure as the
water, a lungful at 33 feet (two atmospheres) takes twice as much out of your tank as does
the same breath at the surface. At 99 feet (four atmospheres) it takes twice as much as at
33 feet.
There's absolutely nothing you can do about that except to avoid being deeper than you
have to be. If you're making a transit over an uninteresting sand flat to get to the edge of the
drop-off, do it at 15 feet instead of at 40 feet, and you'll save air.
Minimize the Lead
If you're overweighted, you have to put more air into your BC to float it and be neutral. The
inflated BC is larger and requires more energy and oxygen to push it through the water.
An extra eight pounds of lead means your BC is one gallon bigger when inflated enough to
make you neutral. Imagine the extra effort of having to push a gallon-sized water jug
through the water.
Adjust Your Trim
If your body is horizontal in the water, when you swim forward, your legs and fins will pass
through the "hole" in the water made by your head and shoulders. You'll disturb less water
and expend less energy and air.
Many divers, however, swim with their feet lower than their torso and their head higher.
Adjust your trim by moving some lead from your hips to your back--to trim pockets on your
BC or to your tank.
Seek Neutral Buoyancy
Always being exactly neutral is the key. If you're not, if you're slightly heavy or light, you're
constantly using fin power (and air) to maintain a constant depth. If you're not neutral, you
can't glide between fin strokes and you can't hang effortlessly.
Streamline Your Gear
All fast-swimming fish have smooth skins with few or no protuberances. That minimizes
drag so they can swim with the least energy and oxygen consumption. Divers, by contrast,
have rough, convoluted surfaces with all sorts of attachments from scuba tanks to whistles.
Anything disturbing the flow of water past your body creates drag and wastes air.
Do your best to imitate the fish. If you don't need a light on this dive, for example, don't take
it. If you do need something, try to hide it in a pocket instead of dangling it from a D-ring.
Take the snorkel off your mask and strap it to your leg or tuck it under your BC or get a
folding snorkel that fits into a pocket. Shorten hoses that are too long. Clip your console
close to your body. Suit your gear to conditions: You don't need the bulk of a BC with 40
pounds of lift in the tropics.
Streamline Your Movements
Keep your arms close to your body. Straighten your legs and keep them as close together
as your fins will allow. Kick with short strokes so your fins stay within the slipstream of your
body. Some fins do require a wider stroke so you have to compromise between efficient
propulsion and streamlining. But usually you're better off finning faster instead of wider.
Breathe Deeply
Any oxygen taken from your tank but not absorbed into your bloodstream is wasted. That's
the case when you take short, shallow breaths. A large part of the air you take in fills your
throat and bronchia, but doesn't reach your lungs before it is expelled again. You have to
take another shallow breath sooner because you didn't get much benefit from the first one,
and a lot of air is wasted.
Instead, try to inhale deeply, filling your lungs completely with each breath. A deeper breath
brings air to more of your lungs' tiny "air sacs" (the alveoli) where gas exchange takes
place. It also adds more fresh air to the volume of "dead air" that remains in your lungs,
throat and mouth from the previous breath, so the mix is richer. When more alveoli are
more fully inflated with fresher air, gas exchange is more efficient: More oxygen is extracted
from the incoming air and more carbon dioxide is released. Although each breath uses
more air, you will take fewer breaths, and the net effect will be that less air is used. Short,
shallow breaths are more frequent and less efficient.
Exhale fully too, so you expel as much carbon dioxide as possible. Anything not exhaled is
carbon-dioxide-heavy "dead" air. On your next inhale, that dead air--instead of fresh
air--partially fills your lungs. The urge to take the next breath is triggered not by lack of
oxygen but by excess of carbon dioxide, so you find yourself inhaling again sooner. On the
other hand, a deep exhale extends the time before you feel the need for another breath.
Breathe Slowly
You consume considerable energy just by breathing, by sucking the air in and pushing it
out again. To inhale, you have to suck open a demand valve in your second stage and pull
gas down your throat and into your lungs. Each inch along the way and each corner the gas
stream turns mean friction and turbulence. Both increase the effort you put out in just
breathing and decrease the amount of gas that actually gets to your lungs. Friction and
turbulence are unavoidable, but the amount goes up dramatically when you try to breathe
quickly--just as a faster-moving boat creates a bigger wake. The problem gets worse as
you go deeper because the gas is thicker--it's like trying to suck a milkshake instead of
water through a straw.
So don't force it. Try for a long, slow inhale until your lungs are full, then a long, slow exhale
until they are empty. More air will get to your lungs, it will spend more time there exchanging
"good" for "bad," and you will use less energy pushing the air back and forth.
Upgrade Your Gear
Overhaul your regulator on schedule and consider one with lower work of breathing,
especially if you often dive deep. ScubaLab tests have shown that the work of breathing
demanded by some regs can be three times as much as others, even more. A
"hard-breathing" reg not only demands more energy and therefore oxygen just to operate it,
your difficulty breathing through it increases your anxiety level and elevates your breathing
rate. So it wastes gas two ways.
Get in Shape
Two people climb a flight of stairs. At the top, one is huffing and puffing and the other is
breathing normally. The heavy breather is getting more oxygen, but he's wasting a lot of
what he inhales because he's breathing so rapidly there isn't much time for gas exchange.
It's an adaptation that makes sense only on land where the air supply is unlimited.
Diving can be surprisingly strenuous because water is so much denser than air.
Swimming into a current, it's not difficult to elevate your breathing to the very wasteful rate of
huffing and puffing. But even much lower levels of exertion will cause your breathing rate to
rise. How much it rises and how soon depend mostly on your aerobic conditioning. A diver
in better condition will have less increase when the workload goes up, so he will use less
air. The other part of getting in shape is to lose fat and achieve a more streamlined shape.
Stay Warm
Even warm water is cold when you're immersed in it, because if it's cooler than about 95
degrees, it takes heat out of your body at a surprising rate. Heat is energy that has to be
replaced by metabolism, using oxygen to make it. Getting cold also creates mental stress
which, often without your noticing it, increases your breathing rate.
And Just Chill Out
The competition over who uses less air can itself be a problem when divers associate low
gas consumption with diving skill, virtue and the right to take up space on the boat. It's one
of those self-fulfilling prophecies: You worry about using more air than your buddy, which
causes stress, which elevates your breathing so you do, in fact, use more air.
In fact, a higher rate of air consumption can be caused by many things, some of them
fixable and some not. In itself it means little or nothing and is nobody's business but yours
and arguably your buddy's--who, we hope, is not out to ruin your day. So if you'd like to
reduce your gas consumption, work gradually on reducing your lead, controlling your
buoyancy, improving your shape and posture in the water, going slowly, breathing slowly
and relaxing. Then forget about it. That alone will help.
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