A partnership of low-profile treasure hunters, operating on the outer edge of ocean engineering technology, has laid claim to what it believes to be one of America's most historic shipwrecks, a paddle-wheel steamer sunk in 1857 with some $450 million in gold coins from the California Gold Rush.

The broken wreck of the U.S. Mail Steamship Central America, which went down in a hurricane with a loss of 428 lives, lies in 8,000 feet of water just within the 200-mile continental limit off the South Carolina coast, according to the Columbus America Discovery Group, a limited partnership based in Columbus, Ohio.

The partnership, which claims to have found the wreck "with many characteristics of the Central America" last summer and salvaged anthracite coal from its boilers, made public its discovery after suing successfully in U.S. District Court in Norfolk last week for jurisdiction over its claim.

"This is not some blue-sky treasure hunt looking for investors," said Thomas G. Thompson, 35, founder and principal director of Columbus America. "We are fully funded through our recovery phase."

He said the partnership's chartered 220-foot salvage vessel Nicor Navigator has been on the site since May 25 filming the wreck with underwater cameras, prior to anticipated salvage next year, which he said would be accomplished entirely by undersea robotics.

The sinking of the Central America was nearly as famous in the 19th century as that of the Titanic is in ours, and it occurred at a similar technological plateau in the Industrial Revolution. It even gave the town of Herndon, Va., its name.

The golden age of American sail, which burst on the world with the brutally fast and majestic clipper ships in 1848, reached its apogee in the Gold Rush years as the towering square-riggers raced around Cape Horn from New York to San Francisco in as little as 90 days. But completion of the railroad across Panama in 1855 spelled the doom of the clipper ships. More and more passengers and shippers chose to avoid the hazardous Cape Horn passage under sail for the steady, if prosaic, route by steam packet down the coasts to the isthmus and across by rail.

The Central America had completed 43 such voyages between New York and Panama when it left the isthmus in September 1857, carrying a regular monthly shipment of gold from the new San Francisco mint to the banks of New York. Some historians say its failure to arrive prevented the banks from staving off the Panic of 1857, which was one of the major economic depressions of the 19th century.

The gold was an official government shipment valued at $1,219,189 in 1857 dollars, when gold was valued at roughly 90 cents to the ounce. Yesterday gold closed at $448.10 to the ounce.

Records show 103 crew members and 478 passengers -- many of them home-bound prospectors carrying their own gold -- were aboard the Central America when it left Havana after a brief stop Sept. 8, 1857, and headed north for New York. Three days later it steamed into a hurricane and began to take on water.

As the rising water extinguished the boiler fires, and the power to the pumps, the passengers bailed with buckets for 30 hours -- buying time enough for all 31 women and 29 children aboard, as well as 39 male passengers and crewmen, to be safely transferred by boat to a nearby sailing vessel, according to contemporary newspaper accounts. But the steamer sank shortly after dark Sept. 12. Fifty-four men were later rescued from the water by other passing ships but 428 passengers and crew were lost.

Among those lost was Capt. William Herndon, a crusty U.S. naval officer who earlier had pioneered exploration of the upper Amazon and reportedly went down with his ship, in full dress uniform and lighted cigar. He had been commanding a civilian ship because of its cargo of federal gold. Surviving passengers so praised his valor that a monument to him was erected at the U.S. Naval Academy in Annapolis -- the only such to an officer not lost in wartime. Plebes grease and climb the obelisk annually in one of the academy's June Week rituals.

The survivors' accounts of the Central America's sinking were flashed around the country by the relatively new invention called the telegraph, making the loss one of the world's first media events.

According to the town records of Herndon, Va., the municipality got its name when one of the survivors addressed a meeting of Fairfax County citizens shortly after the sinking and impressed them with the captain's heroism.

Columbus America's Thompson said he first learned of the disaster in 1977 after researching shipwrecks as a hobby. A mechanical engineer from Ohio State University who had worked as a research scientist on ocean mining projects and as a project engineer on evaluations of the Trident submarine, he said he became convinced that the accelerating advances in undersea technology would make possible recovery of deep ocean wrecks some time in the 1980s.

The catalytic event, he said, was the development in 1985 of a computer-based imaging system that permits ocean searchers to view on a video screen the profile of objects far below even as they are being detected by a towed apparatus that bounces sound waves off the ocean floor.

He said the Columbus America Discovery Group, which was founded that year, consists of 106 partners, almost all of them from Columbus. It has raised some $5 million for the search and recovery effort, he said, of which about $2.2 million has been spent so far.

He described the group's 20-member staff as multidisciplinary. Many of them, he said, have learned their trade in the shadowy world of what he calls "the search for military anomalies" beneath the sea.

He said the group weighed several other projects, but decided on the Central America "on the basis of risk evaluation and ... the data base." He said the reports of survivors and rescuing ships placed the probable location of the wreck on the Blake Ridge, a vast, virtually featureless undersea mud flat where virtually "any lump on the sea floors has to have been left by man."

He said the group's 40-day expedition last year located nine such "cultural deposits" but only one with the features of the Central America.

"She was pretty distinctive," he said, "a wooden-hulled side-paddle steamer, which they only made for about 40 years."

He said the group plans to press forward with salvage efforts next year, spurning manned submersibles for a "bottom-based remote system" operated from ships on the surface. It will be, he said, a significant departure from the undersea technology employed so far in the exploration of any shipwreck, including that of the RMS Titanic.

Barry Schatz, a writer and researcher who is one of the directors of Columbus America, said the exact value of what will be recovered remains much in question. "So many ship salvors come up with a lot of wild claims; we have restricted ours to just what the public manifest shows was the government cargo, in 1857 dollars. Obviously that would be greatly increased by the numismatic value of the coins themselves and the historic artifacts on board," particularly those of the passengers.

Contemporary accounts claimed many of those lost were former prospectors dragged down by bags of gold with which they were loath to part