Using a variety of remote sensing instruments, researchers from NOAA, the Office of Naval Research and East Carolina University conducted the first comprehensive hunt for lost Civil War vessel Alligator, the U.S. Navy’s first submarine, in August 2004.
The search took place off Cape Hatteras, N.C. in the “Graveyard of the Atlantic,” where the 47-foot-long green Union sub was lost during a fierce storm in 1863. Operating from ONR’s 108-ft. YP-679 “Afloat Lab,” a former navy training ship now used for outreach, education and research, the 10-person expedition team used sidescan sonar, a magnetometer and a remotely operated vehicle to comb more than 50 nautical miles of the sea floor for the elusive sub.
|NOAA and East Carolina University researchers deploy a sidescan sonar towfish from the Office of Naval Research's YP-679 Afloat Lab. (Photo: David Hall /NOAA)
(Click on the image for a large version)
During the first cruise alone, the crew spent more than 17 hours carefully surveying the search area and recorded two large magnetic anomalies that warrant further investigation during future expeditions.
“What an exciting way to start off the hunt!” said National Marine Sanctuary Program Marine Archaeologist Michael Overfield, chief scientist for the 2004 Hunt for the Alligator expedition.
The search area was based in part upon research conducted by NOAA’s Office of Response and Restoration Hazardous Materials Response Division in Seattle, Wash., which has experience in predicting how wind, currents and other oceanographic processes might move an object on the water.
“The challenge is going back 150 years and interpolating the data to find a sunken vessel,” said Marc Hodges, a trajectory analyst with the Office of Response and Restoration. “From a trajectory modeling perspective, it’s a very interesting challenge. But it’s one we welcome.”
A National Weather Service meteorologist, meanwhile, reviewed historical records to develop a portrait of the storm during which the Alligator was lost.
“I went through some old Civil War letters and ships’ logs and they mentioned that they had a terrible storm around Cape Hatteras,” said Marine and Hurricane Program Leader James Eberwine with the National Weather Service office in Mt. Holly, New Jersey. “From [the records], I surmised that it intensified off Hatteras. It must have been quite a ferocious storm.”
Faculty and students from ECU’s Program in Maritime Studies and the U.S. Naval Academy sailed with the “Alligator hunters” during the expedition, helping to deploy and recover the yellow, torpedo-shaped sidescan sonar and metal-detecting magnetometer “towfish” from the research shipwhen the weather cooperated.
“Weather at sea is always variable,” wrote National Marine Sanctuary Program Director Daniel J. Basta in a log for the expedition’s Web site during a visit to the Afloat Lab. “Today is like any other day: some wind, some rain, and periodic high seas. Searching for shipwrecks, especially the Alligator is not for the timid, nor the impatient.”
Also on board, on a rare calm day at sea, were a teacher and student from the Stone Ridge School of the Sacred Heart in Bethesda, Md., who had the opportunity to learn first-hand what goes into conducting ocean-based research as part of the Alligator Teacher-and-Student-at-Sea Program.
“It was good to assist in some small way in the search for the Alligator,” said Paula Charbonneau, a senior at Stone Ridge School who, as a 2003 summer intern with the National Marine Sanctuary Program, helped research weather conditions at the time of the Alligator’s loss. “It really isn’t just a story for the archaeologists. It’s something we should all be interested in and excited about.”
During the expedition, NOAA and ONR provided residents and visitors of North Carolina’s Ocracoke Island, where the expedition was based, with an inside look at the hunt for the Alligator through tours of the research vessel, a display at the Ocracoke Preservation Society, and a free public presentation. An overflow crowd of more than 250 people attended the event, which was held under a large tent next to the docked research vessel.
The National Undersea Research Center at the University of Connecticut worked with Alligator expedition team to develop educational video and materials about the search. According the center’s director, Ivar Babb, the video will be available for teachers and students to view on their own time and schedule via a Web interface.
“The team is committed and enthusiastic,” said Babb. “I hope we can encapsulate this excitement in our video content as well, for this is the essence of exploration and discovery.”
The Science Channel also filmed the search for a feature documentary on the Alligator that will air Oct. 5, 2005.
The 2004 Hunt for the Alligator expedition was part of an effort initiated in 2002 by ONR and NOAA to learn more about the largely forgotten sub while fulfilling NOAA’s mission to promote scientific research, exploration and education.
“The wonderful thing about the Alligator is that it’s getting people to learn about meteorology and oceanography,” said Basta. “It’s also about building partnershipswith the Navy, with the private sector, with universities. And it’s getting people focused on the oceans and our maritime heritage.”
Marine archaeologists from NOAA’s Maritime Heritage Program, housed within the National Marine Sanctuary Program, are contributing to the Alligator project decades of experience studying and protecting historically significant shipwrecks, including the Civil War ironclad USS Monitor.
In December 2003, NOAA and ONR unveiled the only known blueprints of the sub, which were discovered in France last year by the National Marine Sanctuary Program’s Catherine Marzin.
Built in 1862, the hand-powered Alligator represented a significant leap forward in naval engineering. Among the sub’s most notable features was an airlock designed to allow a diver to exit the vessel while submerged and place an explosive charge on an enemy ship. The Alligator’s design also included an air purification system. Both are standard components of modern submarines. But before it could prove itself in battle, the Alligator was lost in April 1863 while being towed to Charleston, S.C. to participate in a Union assault on that city. No one was aboard.
Severe weather off the North Carolina coast halted the expedition before the research team could adequately “groundtruth” the two “targets of interest,” but their work continues on shore.
“We are now reviewing the sonar and magnetic data we collected for clues about the Alligator’s whereabouts,” said Overfield. “When we go through the post-processing phase of the search, new targets will be revealed. So, stay tuned. The hunt continues.”
But even if the team doesn’t find the Alligator, Overfield added, the data will help scientists gain a better understanding of what lies off the shores of Cape Hatteras, whether biological, geological or man-made.
“The Alligator is an exciting project because it’s a small object in a challenging part of the ocean,” said expedition participant Cmdr. Jerry Stefanko of the Office of Naval Research. “If we can find the Alligator, we can find anything.”