Page 7: of Marine Technology Magazine (July 2005)

8 MTR July/August 2005

Scientists Find Hidden Dangers to Passing Ships

Using inflatable boats, a portable depth sounder with GPS, and a REMUS autonomous underwater vehicle, a team of scientists and engineers has created the first detailed, comprehensive chart of the ocean floor around Palmer Station in Antarctica, revealing previously unknown submerged rocks.

The new chart, the first in 50 years, was made by a research team from the Woods

Hole Oceanographic Institution (WHOI) and the University of Southern Mississippi over five weeks in April and early May as they looked for sites for a new underwater observatory.

Their findings revealed a number of previ- ously unmapped submerged rocks, among them a set of sharp rocky pinnacles that are potential navigational hazards. Some rise nearly 100 m (about 330 ft.) to a depth of six meters (about 20 ft.) below the surface and near to the routes generally taken by ships through the area.

The previous nautical chart of the area was produced in the mid 1900's by single soundings taken at very wide spacing.

Although some underwater hazards were marked on the earlier chart, the old chart was found to be incorrect by at least 0.5 nautical miles.

Since Palmer Station was first established as a scientific outpost in 1965, ships have followed a particular route through the visi- ble rocks.

In typical marine navigation in poorly charted waters, ships new to the area pro- ceed cautiously, making continuous sound- ings with their bridge fathometer. They then note their routes on charts and follow the same routes when entering and depart- ing the area.

Palmer Station is one of three U.S. research stations on the continent and the only station north of the Antarctic Circle.

Named for American sealer Nathaniel B.

Palmer, who in 1820 was one of the first to see Antarctica, the station was built in 1968 to replace the prefabricated wood huts of 'Old Palmer' station, established in 1965.

Gallager, Asper and their team went to survey the sea floor around Palmer Station to locate possible sites for the installation of the first underwater cabled observatory in

Antarctica.

The Polar Remote Interactive Marine

Observatory (PRIMO) will be equipped with sensors to monitor ocean properties during an entire year.

It will be installed in the Austral fall of 2006 about two nautical miles to the south of Palmer Station on the ocean bottom at a depth of approximately 130 m (425 ft.), connected by a fiber-optic and electrical cable to a newly constructed building at

Palmer Station.

Instruments, including current meters, plankton imaging systems, and an under ice video observation system, will travel up and down through the water column through- out the day from the observatory's base to just below the surface, even after the pack ice forms and covers the area.

Proximity sensors on the top of the profil- ing platform will send and receive acoustic signals to prevent it from contacting the ice.

The scientists hope to use this first observa- tory as a proof of concept and test-bed for a similar observatory to be located in deeper water. "Protection of the cable and underwater platform from grounding icebergs at depths of 100 m (330 ft.) or greater is a major con- cern, and the primary reason for needing the detailed underwater maps, but finding the rocks was an unexpected bonus of the trip," said Gallager. "The real challenge now is to design and build a platform that will survive the harsh

Antarctic winters in the water and provide us the first ever long-term, high resolution glimpses of what is going on in this region of the Southern Ocean." news

Did You Know?

CO2 is Turning

Oceans Acidic

Britain's Royal Society is warning that carbon dioxide is turning the oceans acidic.

Depending on the rate of fos- sil fuel burning, the pH of ocean water near the surface is expected to drop lower by 2100 than it's been in the last 420,000 years. See "British Scientists Say

Carbon Dioxide Is Turning the

Oceans Acidic," Kenneth

Chang, The New York Times, 7/1/05 (www.nsnet.com)

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