The Race for Riches
Under the sea, treasure hunters and scientists battle for history's bounty
Finding a needle in a sea stack
Locating sunken ships is still a laborious, time-consuming task, but it's becoming much easier and faster with the aid of sophisticated technology. Exploration techniques vary greatly, depending on depth and other variables. Here are some devices that would be used in a shipwreck search.
1 Global positioning system (GPS). The boat's GPS receiver captures satellite signals that provide latitude and longitude coordinates, which help define a search grid on the sea floor.
2 Side-scan sonar. The sonar sends out sound pulses that are reflected back by hard objects on the bottom. These return echoes are recorded, digitized, and sent up the cable to the onboard computer. The computer's plotting software "paints" the acoustic images on the screen, which is overlaid with the geographical coordinates received from the GPS satellites.
3 Magnetometer. Essentially an undersea metal detector, the magnetometer is a passive device that "reads" the Earth's magnetic field for anomalies or distortions. It is sensitive only to iron, significant because objects on wrecks are often wrought from the metal. The magnetometer relays data to the surface for real-time viewing and analysis.
4 Remote-operated vehicle (ROV). An ROV is controlled from a computer aboard the surface vessel. Mounted with powerful halogen lamps, wide-angle and zoom color TV cameras, and video and data links, it can spend hours on the sea floor, gathering detailed information about a wreck site. The robot feeds these data to the surface vessel in real time.
[Illustration labels]: Side-scan sonar; Magnetometer; Shipwreck; ROV
Drawing not to scale
Sources: Marine Sonic Technology Ltd., Geometrics Inc., Deep Sea Systems International Inc.
Research by John Englund
[Map is not available.]
Lost and found
Here are a few examples of the many significant shipwreck sites around the world:
1 Brother Jonathan. Sank near Crescent City, Calif., in 1865; found in 1993. A recent auction of coins from this wreck netted $5.3 million.
2 Whydah. Sank near Wellfleet, Mass., in 1717; found in 1984. Its artifacts were recently shown at the National Geographic Society, but many museums have refused them.
3 DeBraak. Sank near the mouth of the Delaware Bay in 1798; found in 1984. The salvaging of this British warship left it severely damaged, and many of its artifacts were lost.
4 Queen Anne's Revenge. Sank off the North Carolina coast in 1718; found in 1996. Blackbeard's ship, discovered by a private firm but later turned over to North Carolina.
5 SS Central America. Sank off the coast of the Carolinas in 1857; found in 1988. The hunt for this ship inspired a 1998 book, Ship of gold in the Deep Blue Sea.
6 I-52. Sank in the mid-Atlantic in 1944; found in 1995. This Japanese submarine, which was sunk by U.S. Navy planes, is thought to contain a cargo of 2 tons of gold.
7 Melkarth. Found in 1998. This 2,500-year-old Phoenician trading vessel was discovered in about 3,000 feet of water just east of the Strait of Gibraltar.
8 Skerki Bank expedition. In 1997, eight wrecks were found in this 20-square-mile reef in the central Mediterranean Sea. Among those were five ancient Roman trading vessels.
9 Tektas Burnu. An ongoing expedition near the Turkish city of Cesme, in the Aegean Sea. The crew is excavating a fifth-century B.C. shipwreck of unknown origin.
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