1981 Survey: A Paper Presented to the Thirteenth Conference on Underwater Archaeology

Introduction

The primary purpose of the National Underwater and Marine Agency (NUMA) is to help preserve America's maritime heritage by locating and identifying historically significant shipwrecks. In June 1981, in conjunction with the Institute of Archaeology and Anthropology of the University of South Carolina, NUMA conducted a survey to locate and identify the remains of the Confederate submarine Hunley. The Hunley sank the U.S.S. Housatonic off Charleston Harbor, South Carolina in 1864, becoming the first submarine to sink an enemy vessel of war.

In 1863 James McClintock, Baxter Watson and Horace L. Hunley began work in Mobile, Alabama on a submersible vessel which they hoped would be used to break the Union blockade of the South. With the help of two army engineers, Lt. George Dixon and Lt. William Alexander, they constructed the submarine from an iron boiler twenty-five feet long. To increase the interior dimensions, the builders cut the boiler in half lengthwise and a foot strip of iron plate inserted, giving the vessel a more oval shape. Two wedge-like ends were added fore and aft, making its final dimensions thirty-five feet long, five feet high and four feet wide.

By design, the sub could be lowered and raised using water-ballast tanks at the bow and stern. Sea cocks and force pumps were installed to facilitate this procedure. The crew propelled the. sub by a hand crank which ran the length of the vessel and connected to a two-bladed propeller. The vessel could obtain a speed of four to five knots in calm water.

Conning towers were installed fore and aft for the purpose of boarding, The eight crew members sat in alternating spaces in the center of the vessel, facing one another. The skipper was positioned forward; the second officer aft. Hunley constructed the sub so that air could be replenished by using hinged pipes which could be raised or lowered. The device, however, did not work as designed, thus making it necessary to surface when the crew needed air. The sub could stay submerged for as long as two and a half hours.

By design, the vessel was to tow a torpedo on a 200 foot tow line. The sub would submerge under the enemy vessel dragging the device against the side of the ship.

After testing in Mobile, the sub was taken to Charleston to be used against the blockade. Tests there proved disastrous. Three Confederate crews were lost in attempts to perfect the sub's performance. Horace L. Hunley, the sub's primary financial backer, was among the last test crew.

After Hunley's death, Dixon and Alexander came from Mobile and asked General Beauregard, who commanded Charleston, for permission to make changes in the sub, now named the Hunley, and continue with the Hunley project. Beauregard agreed, but on the condition that the Hunley not submerge, and that the torpedo be placed on a spar extending from the bow instead of towing it astern the vessel. The torpedo now was designed to be driven into the enemy vessel, and automatically detonated as the sub backed clear.

After acquiring another volunteer crew and completing a series of successful tests, Dixon and Alexander began nightly attempts from Breach Inlet, S.C. to destroy a blockade vessel. They tried without success through the fall and winter of 1863-64. Finally, on the night of February 17, 1864 they spotted and sank the sloop-of-war U.S.S. Housatonic, but the Hunley never returned.

The Hunley's disappearance has caused much debate. Did she go clown with the Housatonic, did the explosion disable her crew causing the sub to drift out to sea, or did she sink on her way to Breach Inlet?

Lt. Colonel O.M. Dantzler, commanding Battery Marshall at Sullivan's Island, claimed to have exchanged prearranged signals with the Hunley after the attack. Because the Hunley had very little positive buoyancy, she could have sunk relatively easily between the Housatonic and the inlet, especially if the conning tower had been open to make a signal.

There are claims that the Hunley was seen lying next to the Housatonic; that possibly the sub went down with the Housatonic due to the suction of the sinking vessel, but this cannot be proven. The Housatonic had only fifteen feet of clear water under her keel and sank in five minutes. A sinking rate of three feet a minute would cause little suction.

The wreck of the Housatonic has been examined many times. The United States Navy examined the vessel in November 1864 and dragged an area 500 yards around it, searching unsuccessfully for the sub. Soon after the war, the wreck was blasted to a level of twenty feet below mean low water.

A contract for removal of the wreck was issued to William L. Virdin in 1909. Virdin was able to reduce the wreck to the required twenty-seven feet below mean low water and found no Hunley nearby.

Later, the Army Corps of Engineers blasted and dragged the Housatonic away to clear the Charleston channel. Its remains now lie approximately 1000 yards east of the channel under six to twelve feet of sand.

In July, 1980 NUMA began its search for the Hunley based on the theory that she nearly made it back to Breach Inlet after the attack. An area of high probability was established between the point of the sub's departure and intended return, and the site of the Housatonic. In 1980 NUMA handled the search in a two-pronged fashion. The area closest to the shore was surveyed with a rubber zodiac boat equipped with a proton magnetometer.

Using a thirty-eight foot research vessel equipped with a sub-bottom profiler, the remains of the Housatonic were located five miles off shore. The 1990 group located four Hunley-sized anomalies in the offshore area and one small anomaly in the inshore area. The offshore anomalies were identified as the Housatonic, and the inshore anomaly was too small for a Hunley-sized vessel.

The Survey

NUMA returned to Charleston in 1981 with a main crew of ten people, several part-time volunteers and high hopes of finding the Hunley.

The area selected for the 1981 survey was simply an extension of the previous summers search. NUMA contracted with the State of South Carolina to survey an area approximately one and -a half miles on either side of Breach Inlet along the surf line, extending five and a quarter miles offshore just past the wreck of the Housatonic. (See figure 1) This part of the South Carolina coast, typical of the southeastern United States, is characterized by a sandy bottom and gradual increase in water depth. At the outermost boundary of our survey area, five miles out, the average water depth was twenty-five feet.

As the 1981 project crew had less than one month to cover nearly fifteen square miles of ocean, NUMA and State representatives again chose a section of the contracted survey area which they believed to be the most likely place for the Hunley's remains. Initially, this proved to be an area covering about four square miles; however, the area was eventually extended two miles further out to the Housatonic wreck. (See figure 1)

We decided upon a survey mode that involved running thirty meter wide search lanes parallel to shore. (The shoreline on this stretch of the South Carolina coast runs southwest and northeast.) Using a state of the art navigation system, a survey vessel towing a magnetometer was guided along predetermined search lines. Any anomalies recorded were investigated by a second vessel which carried a gradiometer for in-site delineation and which served as the dive platform. For these purposes, NUMA employed the use of a twenty foot McKee Craft, loaned from the State of South Carolina, and a thirty-two foot Broadwater Cruiser.

For our primary survey a modified Elsec proton magnetometer, operated by Bill Shea of Brandeis University, was carried aboard the McKee Craft. Towing the mag sensor fifty feet astern, this boat became the workhorse for the entire expedition. Assuming the Hunley weighed three to four tons, and allowing for considerable metal deterioration over the last 117 years, we estimated we were looking for an anomaly of about 200 gammas.

The Hunley was made from an old boiler with few non-ferrous parts; therefore its signal should be strong and clear.

The McKee Craft was guided through the search with the aid of a Motorola Mini-Ranger III tracking system. The Mini-Ranger is a state of the art system that operates on the principle of pulse radar and line of sight. Basically, it determines the position of the vessel being tracked by trilaterating range information from a series of receiver/transmitter units. Two of these units were located at a base station, one at a fixed reference point, and another on the vessel being tracked.

We established our base line between an ocean front house on the north end of the Isle of Palms and the United States Coast Guard lighthouse on Sullivan's Island, five and a quarter miles (or 8,773 meters) to the southwest. (See figure 2) The beach house served as our base station where we placed the Mini-Ranger console and two receiver/transmitter units. Another R/T unit was placed on the lighthouse, serving as the fixed reference station, and the fourth on our survey vessel. As additional survey aids, a MR data processor, X-Y track plotter, track indicator, data input and print-out terminal, and a cartridge tape recorder were interfaced with the range console at the base station. (See figure 3) When the survey vessel's position was received at the base station it was automatically recorded by the X-Y track plotter. Using this and the track indicator, Mini-Ranger operators were able to give instant course corrections over CB radio.

When an anomaly was found, the message "Target " was radioed to the base station. The MR recorded each target on the track plotter and assigned it an X-Y coordinate. The target's position (allowing for the fifty-foot gap between the R/T unit on the boat and the mag sensor) and mag reading were correlated and recorded on a survey map at the end of the day.

As the survey progressed, Mini-Ranger crews noted two areas of interference running diagonally (east to west) through the survey zone. (See figure 4) When the survey vessel moved into this disturbance the Mini-Ranger lost the tracking signal, stopping the plotter. During this time, the boat covered sixty to seventy meters before the tracking made resumed. However, if an anomaly were encountered, the input and printout terminal interface enabled us to record the exact time the boat entered the disturbance and the exact time the anomaly was recorded. Knowing the boat's speed, calculated at the start of each run, we would be able to determine a fairly accurate position for the target.

Seventeen consecutive days of running search lanes produced nineteen positive anomaly positions. Of these, four were picked to be investigated as possible Hunley targets. (See figures 5 and 6) In-site investigations were conducted from the thirty-two foot Broadwater Cruiser. This vessel was equipped with a receiver/transmitter unit, a Schonstedt Instruments gradiometer, and a gas-powered compressor with a four-inch airlift.

Using the Mini-Ranger and the Schonstedt gradiometer the vessel was usually positioned over targets recorded during the previous day's search. A team of two divers would make a preliminary bottom survey on the chance that part of the target lay exposed. In every case but one, the remains were buried. Using steel probes in six foot sections, divers tested the area to locate the target. If contact were made they continued to probe to determine its depth and size. These initial tests determined whether the site warranted further investigation. If so, the airlift would be sent down and the divers would move enough overburden to make a positive identification. In each case, once we discovered that the target was not the Hunley, the investigation ended.

There were four targets investigated during the survey. Three were identified by using probes and a fourth by probing and airlifting.

Mini-Ranger target #1 was located in the Housatonic wreck area. probing indicated the target was composed of wood and iron possibly part of the Housatonic wreckage.

Mini-Ranger target #2 was the only anomaly of the four protruding from the bottom. Upon investigation, this proved to be some type of 20th century wooden ship possibly a fishing vessel.

Mini-Ranger target #27 was probed and found to be a wooden wreck lying about four feet beneath the sand.

Mini-Ranger target #45 was an interesting and puzzling discovery. Probes made contact about one foot beneath the bottom. After more probing, divers determined it to be a long narrow metal object of considerable size. Everyone held their breath.

The airlift was taken down to expose a portion of the target. Divers uncovered a section of a torpedo-shaped cylinder. Further lifting and probing indicated that the object, whatever it was, was not the Hunley.

Diving conditions during the survey were generally poor. Average visibility was one to two feet with strong bottom currents, making surveys and airlifting difficult. A total of fifty-seven dives were made investigating the targets, totaling thirty-nine hours and twenty-five minutes underwater. Many days it was too rough to dive in the survey area.

Secondary Objectives

From historical research, NUMA knew of the existence of. several other Civil War wrecks in and around Charleston Harbor. In addition to the Hunley Survey, we attempted to locate and identify: the Union monitors Keokuk, Weehawken and Patapsco; the Confederate gunboats Charleston, Chicora, and Palmetto State; and several blockade runners, including the Ruby, Raccoon, and Stonewall Jackson.

In 1980, NUMA tentatively located the monitors Weehawken and Keokuk. This year we were able to relocate and probe these sites.

The Weehawken lies south of Charleston Harbor off Morris Island. She was buried at a depth 8 feet. The Keokuk lies south of Charleston Harbor off Lighthouse Inlet. Probing indicated that she lies buried beneath approximately four feet of sand.

NUMA investigators found the Union monitor Patapsco exposed in a well-washed area 800 yards off Fort Sumter. Divers found iron and coal in the wreckage; however, positive identification was based on the discovery of several fifteen-inch shot lying within the remains.

NUMA also searched the Cooper River for the remains of the Confederate gunboats Charleston, Chicora and Palmetto State. Several large magnetometer readings were obtained in the general area of their destruction, but upon examination only ferrous garbage was found. We concluded that over the years the gunboats have been the victims of the Army Corps of Engineers' dredging projects.

NUMA searched for the blockade runners Ruby, Raccoon, and Stonewall Jackson. Although investigative dives were not made on the Ruby or Raccoon significant magnetometer readings were obtained near their reported wreck sites. (See figure 7)

Records indicated the Stonewall Jackson had run aground on the south end of Isle of Palms in 1863. Using information from local residents, we tested an area at low tide with the Schonstedt gradiometer and recorded a strong reading high on the beach. After delineating the site's boundaries with the gradiometer, we probed to a depth of six feet without reaching the target. Due to the unusual site conditions, standard site-testing methods were impractical. We therefore obtained a backhoe to remove as much of the overburden as possible. The backhoe was able to remove six feet of sand at which point we probed nine to ten feet, still without striking the target.

We then utilized a water jet probe which went fifteen feet before making contact. Coal and wood were flushed to the surface, suggesting the presence of a wreck approximately twenty feet below the beach.

Conclusions

We surveyed eight square miles off of Breach Inlet locating several wrecks and also the possible sites of three ironclads and three blockade runners. Some kind of immediate action by the State of South Carolina should be taken to protect the exposed remains of. the Patapsco lying off Fort Sumter.

We know where the Hunley's not. We also believe that the sub is not among the wreckage of the Housatonic. One possibility is that the sub's crew was disabled by the explosion and the vessel drifted out to sea. Sailors aboard the Housatonic reported the Hunley had moved off about fifty feet before the explosion. The torpedo was designed to go off when the sub was about 200 feet clear to avoid injury to the crew.

At this time NUMA has no plans to return to Charleston this coming summer unless research reveals new clues to the Hunley's whereabouts.

References Citied

Blair, Carvel Hall. "Submarines of the Confederate Navy," U. S. Naval Institute Proceedings, LXXXIV (October, 1952), 1115-1121.

Gronquist, Wayne and Walt Schob. Project Hunley, A Paper presented to the 12th Annual Conference of Underwater Archaeology.

Mini-Ranger Tracking Systems, Motorola, Inc., (1980), Procedures Manual.

Perry, Milton F. Infernal Machines: The Story of the Confederate Submarines and Mine Warfare. 1965. Louisiana University Press.

Simms, Lydel. "The Submarine That Wouldn't Come Up," American Heritage XI, No. 3, I(April, 1958), 46-51, 107-111.

United States Navy, Naval History Division. Civil War Naval Chronology 1861-1865. 6 vols. Washington: U. S. Government Printing Office, 1971.