The archaeologists ran a survey out in the area with a magnetometer (like an underwater metal detector) being towed behind the boat and that is when they found the wreck.
A lot of research has been done on the Agnes E. Fry which seems to be the likely name of the shipwreck as the three other blockade-runners known to have been sunk in the area, only the Fry was longer than 200 feet and this one is 225 feet long. The paddle wheels and engine is missing.
The Fry's engine was one of the topline engines available in 1864 and burned smokeless high grade coal when attempting to run the blockade to avoid detection by Union ships seeing the smoke from the smokestack. The paddlewheels, one on each side, had paddle wheel blades especially designed to prevent splashing, another way Union ships would detect blockade-runners.