ng its discovery and recovery a challenge.
Finding it took special sonar. Photographing it for archaeological surveys and artifact collection took powerful lights and cameras. Mapping the position of each artifact took precision gear linked to a network of sonic beacons set up around the wreck. And lifting 52,000 coins and 12,000 artifacts -- the haul so far -- took the precise control of a tethered robot nearly the size of a tank, its arms dexterous enough to thread a needle.
''It's all about computers and digital technology,'' Mr. Stemm said. ''It adds a whole lot of archaeological capability to the operation.''
''We're doing it to an extreme that nobody else has taken it to,'' said Tom Dettweiler, the project's manager and a deep-sea veteran who helped discover the Titanic's resting place.
Clad in dark blue overalls, James Andrade, a supervisor of robot operations with a weight lifter's build, showed off a high-tech control room crammed with panels and video monitors. At sea, the recovery work can go around the clock, day and night, tedious despite the high stakes.
''Most important,'' he said, ''we have satellite radio and an espresso machine.''
The Republic sailed from New York on Oct. 18, 1865, bound for New Orleans with families, businessmen and a diverse cargo of trade goods meant to help the shattered South recover from the Civil War, its passengers brimming with optimism and a sense of opportunity.
The storm hit off Georgia. For two days, the steamship fought wind and wave. Then the engine failed. The crew and passengers threw cargo overboard to lighten the ship. But the pumps failed and seawater poured in.
Most people made it into lifeboats and a raft. Of 59 passengers and crew, 42 survived. But the cargo of money -- $400,000 in coins, as described in newspapers of the day, including The New York Times -- went down with the ship.
Mr. Stemm and his partner, John C. Morris, began looking for the Republic in the early 1990's. Nothing came of the periodic hunt until July 2003, when, some 100 miles southeast of Savannah, they picked up a tantalizing image on sonar screen. Within a month, the team had positively identified the decomposing wreck by retrieving the ship's bell.
Experts estimated the current value of its lost coins at up to $150 million. Odyssey, a public company, hopes to make a profit mainly by selling coins and setting up shipwreck museums and exhibits.
Late last year, team members flew the tethered robot about 15 feet above the wreckage, taking more than 4,600 digital still photographs and turning them into a detailed photo mosaic.
''We can zoom in on domino stones and see the dots,'' Gerhard Seiffert, the team's data manager, said as he demonstrated the technique at a computer, zooming in on an old domino made of wood and ivory.
Rare coins have a high priority since their sale promises to repay the recovery's high cost. But at first, the team had no idea how to gather them up carefully and expeditiously when even the slightest scratch could greatly reduce their value. Much testing ensued.
The tiny suction cups proved safe and efficient. More troublesome was finding the right holding devices for transporting coins to the surface, despite Mr. Stemm's extensive hunt for solutions. Plastic colanders and ice cube trays proved unworkable.