Search for the Sunken Warriors

Article excerpt

Gentle trade winds blow from the from the south, while the warm bay water laps at the slow-- moving boat as it wends its way back and forth in front of the hangars at Marine Corps Base Kaneohe, Hawaii. Comments can be heard from the boat's occupants: "How about that? That looks like something." "No, it's just a fish."

The boat's movements are reminiscent of a fishing trawler and, in a way, it is "fishing" for something. With remote sensing equipment in tow, the vessel is searching for U.S. Navy aircraft lost during the catastrophic attack on Oahu by Imperial Japanese forces on 7 December 1941.

The Underwater Archaeology Branch (UA) of the Naval Historical Center, Washington, D.C., manages the U.S. Navy's ship and aircraft wrecks. Should the military presence at Kaneohe Bay ever cease, these wreck sites would become vulnerable. It is therefore valuable to know what remains of the aircraft so that a management plan can be designed.

In 1994, the University of Hawaii Marine Options Program (MOP) worked with East Carolina University students to archaeologically investigate and document the wreck of a Consolidated PBY-5 Catalina in Kaneohe Bay. Subsequent research suggested that this plane was one of four lost on the water in 1941. Since 1994, the same archeologists have been hoping to return to find the other three missing planes. Last year, UA granted the MOP's permit application and sent an observer to assist as archaeologists and students (aided by the National Park Service's American Battlefield Protection Program) were again allowed to investigate Kaneohe Bay.

For five weeks in June and July, MOP field school director Hans Von Tilburg led a group of seven national and international students in a course on underwater archaeology, with the Kaneohe wreck sites as the classroom.

Searching for historic aircraft can be a skilled endeavor, or it can be pure luck. Professional underwater archaeologists working with aircraft become accident investigators. They must re-create the scene by researching historic documents and interviewing survivors or eyewitness to the crash, then combine the information with data involving the local topography, currents and winds. From all of these sources a likely search area can be developed. Then, unless the crash site is obvious, archaeologists employ various methods of remote sensing to help pinpoint an area for close visual inspection.

Looking for sunken aircraft with remote sensing is slow and tedious, but the results are often rewarding. Remote sensing experts and archaeologists define a search area and the systematically investigate it. This type of search has been called "mowing the lawn" (as the equipment is towed back and forth over the area), and is used to define and map the search area. It is important to cover the entire area as aircraft wreck sites often include a debris field that can be informative as the main wreckage itself. Knowledge of the entire site helps archaeologists more accurately investigate and interpret the remains, and aids in understanding the history.

Since each remote sensing method has advantages and disadvantages, a combination of techniques can be used depending on site conditions. For this search, side-scan sonar and magnetometer were used.

The side-scan transmitter sends out acoustic signals which bounce off the seabed or any object on the bottom. …