Trapped in an Underwater Air Bubble for Three Days
Harrison Okene’s shipwreck survival wasn’t a miracle. It was fascinating physics.
Harrison Okene, 29, stands outside a hotel in Nigeria's oil city of Warri on June 12, 2013.
Photo by Joe Brock/Reuters
Photo by Joe Brock/Reuters
Being buried alive is usually near the top of any worst-ways-to-die
list. But how about being buried alive 100 feet below the ocean surface
in a tiny pocket of air? For Harrison Okene, a 29-year-old Nigerian boat
cook, this nightmare scenario became a reality for nearly three
grueling days.
The story began on May 26 at about 4:30 a.m., when Okene got up to
use the restroom. His vessel, a Chevron oil service tugboat called the
AHT Jascon-4, swayed in the choppy Atlantic waters just off the coast of
Nigeria. What caused the tugboat to capsize remains a mystery, though a Chevron official later blamed a “sudden ocean swell.”
Okene was thrown from the crew restroom as the ship turned over.
Water streamed in and swept him through the vessel’s bowels until he
found himself in the toilet of an officer’s cabin. As the ship settled
on the ocean floor, the water stopped rising. For the next 60 hours,
Okene—who was without food, water, or light—listened to the sounds of
ocean creatures scavenging through the ship on his dead crewmates. Like a
living Phlebas the Phoenician, he recounted his life’s events while growing more resigned to his fate.
Unbelievably, Okene survived his underwater ordeal long enough to be
rescued. Basic physics, it turned out, was on Okene’s side the whole
time—even if Poseidon wasn’t.
When Maxim Umansky, a physicist at the Lawrence Livermore National
Laboratory in California, read about Okene’s miraculous rescue, his
interest was piqued. “For a physics question, it’s an interesting
problem,” said Umansky. “Of course, I’m also glad the man survived and
happy with the ending of his story.”
Umansky began conducting his own calculations to quantify the factors
responsible for Okene’s survival. He also posed a question to a physics Web forum: How large does a bubble have to be to sustain a person with breathable air?
Okene’s salvation—the air bubble—was trapped because the overturned
boat acted as a sort of diving bell, the cup-shaped chambers that have
transported explorers and workers into the depths for centuries. In the
fourth century B.C., Aristotle described the contraptions as enabling
“the divers to respire equally well by letting down a cauldron, for this
does not fill with water, but retains the air, for it is forced
straight down into the water.” Years later, diving bells called caissons
helped 19th-century workers construct the Brooklyn Bridge (though many died in the process).
Whether in a bell or boat, trapped air rises to the top of a concave
chamber. The only way it can escape is by diffusing through the water
itself, one molecule at a time. Eventually this would happen, but Okene
would have succumbed to thirst, hypothermia, or asphyxiation long before
his air bubble diffused into the ocean.
Fans of horror movies will note that asphyxiation typically claims
victims of live burial. Carbon dioxide accounts for about 0.03 percent
of normal air. If someone is trapped in an enclosed space, however,
exhaling CO2 with every breath, the proportion of oxygen steadily
decreases while the level of carbon dioxide increases. It’s the deadly
CO2, not the lack of oxygen, that ultimately kills a person. Once the
air reaches around 5 percent CO2, the victim becomes confused and
panicked, starts hyperventilating, and eventually loses consciousness.
Death follows. In an enclosed coffin, a person may produce deadly levels
of carbon dioxide within two hours or so.
But Okene didn’t asphyxiate despite being trapped in a small, sealed space for 60 hours. How was this possible?
The water encapsulating his air bubble may have played a small role
in his survival. Carbon dioxide, more so than oxygen or nitrogen,
readily dissolves into water—especially cold water. The rate at which
this occurs follows Henry’s law, a physics rule that states that the
solubility of gas in a liquid is proportional to the pressure of the gas
above the liquid. Disturbing the water’s surface, which increases its
surface area, likewise increases the rate of transport of gaseous CO2
into the liquid. But if the volume of gas were too small to begin
with—in other words, if deadly CO2 built up faster than it could diffuse
away—that process wouldn’t have made much of a difference for Okene.
Humans require 10 cubic meters of air per day. So for Okene to
continue breathing for 60 hours, he needed 25 cubic meters of air. (Even
if his metabolism changed in the cold water, Umansky says, this is
still a safe estimate). But Okene was breathing at 100 feet, or 30
meters, below the surface of the water. For every 10 meters a person
descends, one atmosphere of pressure is added. This compresses gas and
makes it denser, according to Boyle’s law.
Since Okene was trapped at 30 meters below the surface, his air
supply became denser by a factor of four. This means he needed only 6
cubic meters of air to survive rather than 25 cubic meters. A space of
about 6 feet by 10 feet by 3 feet would be sufficient to supply that
amount of air. The press reported
that Okene’s chamber was only about 4 feet high, and Umansky speculates
that it must have been connected to another air pocket under the hull
of the boat. “That’s the most reasonable explanation for this miraculous
survival,” he said.
In a lively discussion on the physics forum, about a dozen
participants offered their own calculations and observations. One user,
Anna V., came up with a slightly larger figure for the bubble’s required
size, about 10 feet by 25 feet by 25 feet. An enclosure of this size
“is a reasonable one on a tugboat,” she writes. “He was just lucky the
air siphoned where he was trapped.”
Other people have survived short periods underwater breathing trapped air. In 1991 diver Michael Proudfoot
reportedly spent two days in an air pocket on a sunken ship off the
coast of California after he accidentally smashed his scuba gear. Okene
likely holds the new record for most time spent trapped underwater.
After his rescue, he had to spend another 60 hours in a decompression
chamber to rid his body of excess nitrogen, and some of his skin peeled
off from soaking in salt water for so long. As one of his friends
understatedly wrote on Okene’s Facebook wall, “I feel sorry for u that
happened man.” Dozens of other friends and family members thank God and
Jesus for looking out for Okene, though perhaps a hat tip to physics is
in order, too.
No comments:
Post a Comment