COVER STORY
Exploring Challenger Deep— 35,000 feet and counting
The Nereus hybrid remotely operated vehicle collects core, rock, biological and
water samples, and other materials from more than 35,000 ft. below sea level.
The fictional Captain Nemo piloted his
submarine Nautilus 20,000 leagues
under the sea. But Nereus, a hybrid
remotely operated vehicle (HROV),
enables real scientists to explore the deepest
areas of the ocean. For example, the
Challenger Deep section of the Mariana
Trench— 35,838 feet below sea level—was
visited very briefly four decades ago by pioneering oceanographers. Technology limitations have prevented routine access to
these remote regions, and they have not
been explored in detail until now.
Designed and fabricated by Woods
Hole Oceanographic Institution (WHOI),
Woods Hole, Mass., Nereus can conduct
scientific research while tethered to a ship
12 PRACTICAL WELDING TODAY
May/June 2009
or navigating freely. It can carry a 25-kg
payload for collecting core, rock, and biological and water samples. It also measures
temperature and can take still or video
images. To control the vessel, scientists
send a signal via a fiber-optic cable.
WHOI is a private, independent organization dedicated to marine research, engineering, and higher education. Its primary
mission is to understand the oceans and
their interaction with the Earth as a whole,
and to communicate a basic understanding
of the oceans’ role in the changing global
environment. WHOI is world-renowned
for its deep-sea submersible vehicle Alvin,
which is most famous for exploring the
wreck of the Titanic.
Nereus, the development of which was
funded by the National Science Foundation,
must be able to work under intense pressure.
At Challenger Deep, a portion of the Pacific
Ocean off the coast of the Marianas Islands,
the water is an estimated 35,838 ft. deep and
exerts a pressure of 15,751 PSI on anything
or anyone that dares to navigate at those
depths. That’s more than 1,000 times the
atmospheric pressure at sea level. Needless to
say, weld quality was critical in Nereus.
Keeping It Straight
Before joining WHOI in 1996, Geoff
Ekblaw, senior welder, had more than 20
years’ experience fabricating aluminum
boats for the America’s Cup race, including
