|
 In
"The Uncivilized Machine
of War," Alan meets the archeologists who are restoring
the Hunley, the Civil War submarine that carried out the first
successful submarine attack on February 17, 1864. Raised in
2000, the Hunley is not the first sunken vessel to be brought to
the surface. Lifting a waterlogged ship from the ocean floor
is never a simple task, and each case presents its own unique
set of technical challenges. Here, FRONTIERS explores the
raising of some famous wrecks.
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The
Kursk
On
August 12, 2000, an explosion tore through the double hull
of the Russian nuclear submarine Kursk, sending the
boat to the bottom of the Barents Sea. All of her 118
crewmen were tragically lost in the disaster. In September of the next
year the Russian government commenced an effort to raise the
doomed submarine, enlisting the aid of the Dutch heavy-lifting
and maritime-services companies Mammoet and Smit International.
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Using
a giant saw, engineers remove the damaged bow of the
Kursk before bringing her to the surface.
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The
Kursk presented novel difficulties for the engineers
who were charged with bringing her to the surface. The submarine
was to be lifted from the seafloor by the barge Giant,
suspending the wreck with cables during the slow ascent. However, the explosion that sunk her had significantly
damaged the forward section of the submarine, creating a hazard
for the Giant and her crew. If the Kursk broke
apart while dangling from the lifting cables, the recoil could have placed the Giant
in considerable danger. The engineers therefore decided to
remove the bow section before raising the ship - a formidable proposition, considering that she lay in 360 feet of water.
The
solution was a giant saw, attached to enormous
hydraulic anchors laid on the seabed on either side of the
submarine's hull. Stretching between the 40-foot anchors was
the saw's "blade," a chain of cylindrical drums covered with
an abrasive material and draped over the forward section of the submarine. Suction pumps
in the anchors created a vacuum that pulled them progressively
deeper into the muddy bottom, applying tension to the saw
while powerful hydraulics drew the chain back and forth. The motion of the abrasive chain slowly cut into the hull until, ten days and two chains
later, the bow was separated from the rest of the ship.
Meanwhile,
divers drilled twenty-six holes along the top of the hull in
preparation for the next phase of the procedure. Gripper assemblies
at the ends of the lifting cables were inserted in the holes
and opened up like expansion bolts inside the hull, securing
the ship to the cables. Once the bow was separated, the gradual
ascent of the ship began, but this part of the operation was
not without hurdles of its own.
If
the cables had been attached rigidly to the barge, rough seas
could have scuttled the lifting operation by creating uneven
strain in the cables and attachments. Dangerous oscillations
might have built up in the pendulous Kursk-Giant system,
a potentially disastrous situation if the forces were to exceed
safe limits. To avoid this possible problem, computer-controlled
gas cylinders were installed on the Giant at the attachment
points of the cables. This active shock-absorbing system compensated
for wave action by constantly adjusting the tension in the
cables, dampening any unwanted oscillations.
After
a successful ascent, the Kursk was brought to a depth
just below the pontoons of the Giant and secured to
the barge with large clamps. The entire assembly then steamed
towards drydock in Murmansk, where investigators officially
determined the cause of the fatal explosion to be fuel leaking
from a torpedo.
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