Remote Sensing Investigations of the Civil War Blockade Runner Ivanhoe

History of the Ivanhoe

Ivanhoe was an iron-hulled paddle wheel steam ship built in Greenock, England. She was designed to evade the blockading Union fleet during the American Civil War, delivering much-needed supplies to the South. On the night of June 30th, 1864, the ship was attempting to circumvent the Yankee fleet and sneak into Mobile Bay, Alabama under the protective guns of Fort Morgan. The Union warship Glasgow sighted and opened fire on Ivanhoe, and she was forced aground approximately a mile east of the fort. Gunfire from the fort repelled Union ships while the Ivanhoe's cargo was salvaged, but within a week a Union boarding party was able to sneak to the vessel at night and set it ablaze.

Re-location of the Ivanhoe

In March of 1992, Florida State University set out to re-locate the Ivanhoe. Former searches for the Ivanhoe, undertaken by various other institutions, had proven inconclusive (Cussler 1991). FSU researchers took into account the changing coastal geomorphology, and therefore set out to look for a shipwreck on dry land! Using the Department of Anthropology's Geometrics G-856 proton precession magnetometer, a crew conducted a magnetic survey. In the area where it was believed the Ivanhoe was, the magnetometer registered an anomaly of enoumous magnitude. It was consistent with the reading that a steel-hulled vessel would register. A second magnetometer survey in May re-established the location and pin-pointed the anomaly on current maps. Surface surveys turned up wood fragments, spikes, and nails that could have come from a 19th century ship (McLean and Fischer 1991).

GPR Survey

In August of 1992, a team of FSU student researchers returned to the alleged site of the Ivanhoe (Milman 1994). In order to determine the extent of the remains and to positivly identify the wreck with minimal disturbance, it was decided to use Ground Penetrating Radar (GPR). This was a somewhat controversial attempt, as it was believed that GPR technology cannot normally penetrate a salt water lens. However, the survey produced remarkable results. Using a Geophysical Survey Systems SIR System 3 GPR (on loan from Thompson Engineering), archaeologists determined that, approximately a meter below the water table, there was a buried ship 61.5 meters in lengh and 4.7 to 8.0 meters in width. The historically documented measurements of the Ivanhoe (Wise 1988: 306) were 201.4 feet (61.3 m) in length with a 20.15 feet (6.14 m) beam.

Though no detailed depictions of the Ivanhoe were located, a detailed drawing of a similar ship, the Will of the Wisp, was identified. When the plan of the Will of the Wisp is superimposed with the GPR data (above illustration), several of the Ivanhoe's features, such as cargo bulkheads and the fore and aft cargo areas , can be clearly seen. The data also seems to indicate that the engines and paddle wheels were removed.

This project demonstrated the highly successful utilization of GPR to identify a historic shipwreck. In this instance, the archaeological application of non-intrusive remote sensing (both magnetometer and GPR) was highly effective in assessing subsurface remains with no damage to either the cultural or natural environment.

FSU student researchers could not have undertaken this project without the assistance of local Mobile citizens interested in their maritime history. John H. "Jack" Friend Jr, of the Baldwin County Archaeological Preservation Committee, saw that financial assistance was provided for the Ivanhoe project, and provided personal assistance on-site during field efforts. His original research pinpointed an accurate location for the shipwreck, which was confirmed through magnetometry. Fletcher Thompson, owner of Thompson Engineering, provided and operated the Ground Penetrating Radar. Mr. Thompson also used his extensive experience with GPR records to assist in analysis and interpretation of the data.

References and Further Reading:

1990 Survey of the Civil War Ships, USS Philippi, CSS Gaines, blockade runner Ivanhoe, USS Milwaukee, and USS Osage. Also eighteenth century French merchant vessel, Bellone. Submitted to the Alabama Historical Commission.

Heimmer, Don H.

1992 Near-Surface, High Resolution Geophysical Methods for Cultural Resource Management and Archaeological Investigations. Geo-Recovery Systems, Inc.: Golden, Colorado.

McLean, Shea W and George R. Fischer

1991 Investigations of the Civil War Blockade Runner Ivanhoe. Ms. on file at the Academic Diving Program, Florida State University, Tallahassee, Florida.

Milman, Darren D.

1994 Remote Sensing Survey of the Civil War Blockade Runner Ivanhoe. Report prepared by the Academic Diving Program. Florida State University, Tallahassee, FL.

United States, Naval War Records Office

1961 Official Record s of the Union and Confederate Navies in the War of the Rebellion. Antiquarian Press: New York.

Wise, Stephen R.

1988 Lifeline of the Confederacy: Blockade Running During the Civil War. University of South Carolina Press.