Civil War shipwreck explored by 3-D sonar
BY MICHAEL GRACZYK Associated Press
Sunday, January 20, 2013
The remains of the only
U.S. Navy ship sunk in the
Gulf of Mexico during Civil
War combat now can be seen
in 3-D sonar images from the
Gulf’s murky depths, revealing
details such as a shell hole
that may have been among
the ship’s
fatal wounds.
The high-resolution
images of the 210-foot,
iron-hulled USS Hatteras are
being released this month to
coincide with the 150th anniversary
of the battle where
the ship was lost. Besides the
shell hole, they also show previously
unknown details like
a paddle wheel and the ship’s
stern and rudder emerging
from the shifting undersea
sands about 20 miles off the
coast of Galveston.
“This vessel is a practically
intact time capsule sealed by
mud and sand, and what is
there will be the things that
help bring the crew and ship
to life in a way,” said Jim Delgado,
the project’s leader and
director of maritime heritage
for the National Oceanic and
Atmospheric Administration’s
Office of National Marine
Sanctuaries.
“You can fly through the
wreck, you’re getting a view
no diver can get,” Delgado
said.
The Hatteras had sat mostly
undisturbed and unnoticed
from January 1863 — when
a Confederate raider sunk
the ship and took most of the
crew prisoner — until its discovery
in the early 1970s.
Recent storms shifted the
sand and mud where the
Hatteras rests 57 feet below
the surface, exposing more
of the ship. So archaeologists
and technicians, racing
to beat any potential seabed
movement that could
conceal the Hatteras again,
spent two days last September
scanning the wreckage
using sonar imaging technology
for the first time at sea.
Divers used the 3-D gear
to map the site in the siltfilled
water where visibility
is from near zero to only a
few feet. The water’s murkiness
doesn’t affect sonar
technology like it would
regular photography equipment.
Sonar technology
produces computer-colored
images by analyzing sound
waves bouncing off objects.
“We have very crisp, measureable
images that show
the bulk of the steam machinery
in the engine room is
there,” Delgado said. “Some
of it is knocked over, been
toppled, which suggests we
probably have 60 percent of
the vessel buried.”
The imaging plots the
paddle wheel shaft, which
appears to have been bent
when the ship capsized, and
damage to engine room machinery,
including the shell
hole that likely helped doom
the ship, Delgado said.
The Hatteras site is in
waters administered by the
federal Bureau of Ocean Energy
Management. The ship
itself, even 150 years later,
remains U.S. Navy property.
The 1,126-ton Hatteras
was built in 1861 in Wilmington,
Del., as a civilian steamship,
according to the Navy
Historical Center. It was
purchased by the Navy later
that year, commissioned at
the Philadelphia Navy Yard
and assigned to join the
blockade of the Florida coast
to keep vessels from delivering
supplies and war weapons
and ammunition to the
Confederacy.
On Jan. 6, 1863, the Hatteras
joined the fleet commanded
by Adm. David
Farragut, of “Damn the torpedoes,
full speed ahead!”
U.S. Navy fame, for similar
assignments off Galveston.
On Jan. 11, the Hatteras
spotted and tracked down a
three-masted ship that identified
itself as British, then
opened fire from 25 to 200
yards away and revealed it
actually was the CSS Alabama,
a notorious Confederate
raider credited with
some 60 kills.
Associated Images:
This image shows a drawing of the USS Hatteras, above a 2012 3-D hi-res sonar image. AP Photo / NOAA, Northwest Hydro Inc., James Glaeser
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