No diver should ever run out of air, but it still happens
with alarming frequency. Panicky ascents can lead to
embolisms, blackouts and other primary causes of diver
deaths. But there is a technique that can provide a few
additional breaths – just enough to locate a buddy or start
a controlled swimming ascent. It involves breathing air
directly from your BCD. It’s tricky to master, but when
all else fails, it might save your life – or your buddy’s.
Even if you suck your tank bone dry
at depth, you can still breathe the
residual air in your BCD |
Say you’re 100 feet down with two buddies and both
come to you out of air. If you’re experienced and alert,
you could pass your primary second stage to one buddy
and give your octopus to the second. But what about
you? Begin a slow ascent. Valve fresh air into your buoyancy
compensator with your BCD’s inflator hose and
breathe through your oral inflator mouthpiece. Instead of free-ascending with no air, you’ll have a few breaths of
air from your BCD as you rise, allowing you to make a
slower and safer ascent.
You may have never heard of BCD breathing. You see,
no commercial training agency teaches this technique at
any level. In fact, since we first reported on it several years
back, the industry seems to have closed ranks against it,
even though it’s been successfully tested in various predicaments.
We’re hardly advocating breathing the air remaining in
a BCD as standard practice. It’s only as a last resort. Even
if you suck your tank dry at depth, you can get some air
through your regulator as you ascend and the air in your
tank expands. But once your tank is bone dry, you’ll still
have residual air in your BCD, or at least in your inflator
hose. If you added air with your power inflator, it will be
pure and contain 21 percent oxygen. If you orally inflated
your BCD, it will still contain at least 16 percent oxygen.
Breathing Cycles
Bear in mind that air in your BCD will also expand as
you rise. If you put your BCD mouthpiece in your mouth
and keep trying to inhale and exhale while you rise, your air volume will soon increase enough to provide a breath.
Studies conducted by the late Al Pierce of the YMCA
concluded that you can exhale into your BCD and keep
rebreathing the same air 13 times or more without becoming
overly hungry for fresh air. (After all, exhaled air is
good enough for artificial respiration.) TDI/SDI founder
Bret Gilliam told Undercurrent of a commercial diver
whose hand got trapped under a pipe. To conserve air, he
orally inflated his early edition flotation vest and began
breathing from it until the carbon dioxide rose to an
uncomfortable level. Then he switched back to his regulator,
caught his breath with clean air from the tank, vented
the vest and started the cycle again. After an hour in 50
feet of water, his tank was down to 100 psi and he was ready to amputate his fingers to free himself when another
member of his dive team came by and started buddy
breathing with him.
Why Don’t Agencies Teach This?
It’s partly due to the industry’s resistance to change.
Years ago, when early BCDs could be inflated with carbondioxide
cartridges, there was a concern about breathing
residual carbon dioxide. A more current objection is the
possibility of respiratory infection from bacteria inside the
BCD. Dennis Pulley, director of training at Scuba Schools
International, cited this as the primary reason why SSI
doesn’t teach BCD breathing at any level.
However, BCDs used for training can be disinfected
with solutions readily available in dive shops. Or you can
use benzalkonium chloride, available at drug stores under
the brand name Zephiran chloride. Besides, antibiotics
cure respiratory infections. Drowning is forever.
Nevertheless, the industry remains set in its ways. For
instance, today’s Aqua Lung BCD owner’s manuals still
carry the warning, “DO NOT inhale from your oral inflator.
The BC may contain harmful contaminants or gasses,
which could cause suffocation or injury.” When we
discussed this with Tom Phillipp, Aqua Lung’s product
manager for BCDs, he conceded that it probably needs to
be updated.
The biggest objection is that divers will need to master
new skills and perhaps relearn some old ones. For
instance, you must be able to clear the ounce or so of
water from your inflator hose mouthpiece without choking.
Joel Silverstein, chief operating officer of Scuba
Training and Technology Inc., points out that breathing
in and out of a BCD creates a closed circuit that can
cause carbon-dioxide buildup and lead to shallow water
blackout. Also, your BCD will become more buoyant as
you rise, leading to a possible uncontrolled ascent. Both
dangers can be averted by exhaling through your nose, but
this creates other challenges. First, unless your mask has
a purge valve, it might leak. Second, by exhaling you’re
emptying your air supply and decreasing your buoyancy
– perhaps to the point of being overweighted.
Gilliam, who now advises the industry on training
procedures, told Undercurrent he considers BCD breathing
“a viable independent self-rescue technique.” Yet, he says,
“There is no such drill in any entry level course worldwide.”
As an instructor, he’s noticed that in emergency situations,
many divers adopt a “rigid flight posture,” visibly
stiffening in the water column, which prevents them from
handling such tasks.
Silverstein calls the concept of BCD breathing a “radical
technique” that is not part of any formal training curriculum.
His concern is that most divers just don’t have what it
takes to perform this skill without panicking. “The average
diver makes fewer than 10 dives a year.” He’s convinced that divers who don’t practice the skill continuously “won’t
know how to do it and will kill themselves.”
These are valid considerations, but does it make sense
for certified divers to not even be exposed to this proven
technique for handling out-of-air situations or equipment
malfunctions?
PADI has recommended options for low/out of air situations,
in order of priority. 1) Make a normal ascent if your
tank isn’t completely empty. 2) Ascend using an alternate
air source (redundant supply or buddy’s octopus).
3) Execute a controlled emergency swimming ascent. 4) Buddy-breathe with a single regulator supplied by another
diver. 5) Make a buoyant emergency ascent.
However, isn’t a controlled emergency ascent or a buoyant
emergency ascent safer if you have a few breaths of air
from your BCD? Knowing you’ve got at least one more ace
up your sleeve might help keep you cool as you weigh your
options. Hopefully, you’ll get things under control before
you ever need to use your BCD as an alternate air source.
But it’s there if you need it.
-- Larry Clinton, Jr.