Marine Electronics
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December 2010 Issue
Phoenix Recovers U.S. Navy E-2C Aircraft
Phoenix International Holdings Inc. (Largo, Maryland) successfully recovered a U.S. Navy E-2C Hawkeye twin-turboprop airplane from 3,300 meters of seawater in the north Arabian Sea, Phoenix announced in November.
The Hawkeye crashed March 31 during flight operations from the aircraft carrier USS Dwight D. Eisenhower. The recovery marks the successful conclusion of a two-phased search-and-recovery operation. Phoenix, under the guidance of the office of Supervisor of Salvage and Diving, pinpointed the location of the E-2C during a three day search of a 10-by-10-mile area in mid-April using the Navy's towed pinger locator (TPL) system. TPLs are passive listening devices capable of hearing the acoustic emissions of the saltwater-activated beacon on board the aircraft.
Tasking for the recovery phase of the project was received in May. Given the expected onset of poor weather, the decision was made to expedite the recovery operation by using Phoenix's 6,000-meter-rated remotely operated vehicle Remora, already prepositioned in Limassol, Cyprus. Additional required recovery equipment included the Navy's Fly Away Deep Ocean Salvage System, which is specifically designed to lift heavy, bulky items from deep water using a motion compensator to reduce high snap loading of the lift line. The recovery vessel was EDT ARES, a dynamic positioning Class 2 ship owned by EDT Offshore (Limassol). A security crew was embarked to assure safe transit through pirate-plagued waters to the crash site.
Remora commenced diving on June 9 to relocate the wreck site and to survey the debris field, identifying portions of the E-2C to be recovered for the ensuing crash investigation. The starboard propeller hub and gear box, aircraft wing, fuselage sections and tail were safely recovered over the next three days. For more information, visit www.phnx-international.com.
Army Corps of Engineers Using Altimeter to Protect Assets
Towing expensive oceanographic equipment close enough to the ocean bottom to be effective, yet far enough away to prevent damage, has always been a challenge. To help solve this problem, JW Fishers Mfg Inc. (East Taunton, Massachusetts) developed the UA-2 underwater altimeter, which allows underwater detection and survey equipment to be towed at a precise altitude above the seabed.
The U.S. Army Corps of Engineers has found a rather unique application for the altimeter. Among its many duties, the corps is responsible for monitoring dredge disposal sites. Each year approximately 120 million cubic yards of dredged material are deposited at designated aquatic disposal sites located in 20 to 150 feet of water. The corps monitors these sites to determine long-term physical and chemical stability, as well as remaining capacity.
One common monitoring technique is sediment sampling using a vibrocore system. A problem occurs if the vibrocore head is driven too far and comes into contact with the base, damaging the vibrocore. To eliminate the possibility of this happening, the corps is now experimenting with the use of underwater altimeters. Instead of attaching the altimeter's transducer to the head side of the vibrocore, the sonar transmitter is attached to the base and aimed at the surface. As the pipe is driven into the bottom and the head descends, the altimeter measures the distance between the upper and lower assembly.
Watching the altimeter's display, the operator knows exactly how deep the pipe has penetrated the ocean floor, and also the distance between the head and base.
The machine can then be stopped before the two run into each other, preventing any damage. Army Corps physical science technician Thomas Wyche of the New York District said they tested the UA-2 altimeter using a 15-foot core tube.
"We saw the distance close from the head to the base as it went from 15 feet, 14 feet, eight feet, four feet to the one-foot reading. It looks like it will do the trick and prevent the equipment from getting banged up," Wyche said. For more information, visit www.jwfishers.com.
Fugro Completes Successful 3D Survey Offshore Alaska
Fugro-Geoteam (Oslo, Norway) announced in October the completion of a large 3D survey offshore Alaska in the Chukchi Sea.The project was conducted for Statoil E&P USA Inc. (Houston, Texas) by the M/V Geo Celtic during the relatively brief ice-free season and resulted in the recording of more than 2,600 square kilometers of survey data in 40 days.
Fugro said the survey had minimal loss of time, zero infill and no environmental incidents. The company's personnel and facilities located in Anchorage, Alaska, were used throughout the project. For more information, visit www.fugro.geoteam.no.
Almost Two Dozen Historic Shipwrecks Located in Norway
A three-day survey earlier this year by an international team of researchers resulted in the discovery of nearly two dozen well-preserved shipwrecks in the lakes of the Telemark Waterway in south-central Norway. The waterway has been used for transportation for hundreds, if not thousands, of years. The shipwrecks are suspected to range in date from the Medieval/Viking age to the mid-19th century.
The team, from ProMare (Chester, Connecticut), the Norwegian Maritime Museum, the Norwegian University of Science and Technology, and Teledyne Gavia ehf (Kopavogur, Iceland), surveyed the location over a period of three days, and it will return to the area in the summer of 2011 to continue exploring the waterway for more shipwrecks and evidence of historic and ancient watercraft and commerce.
To locate the shipwrecks, the team deployed a Gavia autonomous underwater vehicle (AUV), provided by Teledyne Gavia, equipped with the latest sonar imaging and inertial navigation systems.
"The Gavia AUV's performance was impressive in what was assuredly difficult and unknown terrain," said ProMare president Brett Phaneuf. "The Gavia AUV made surveying in the deep lakes in Telemark possible and gave us brilliant results we could not have achieved with a towed sonar system or another AUV of lesser depth rating or of a less robust design and construction." For more information, visit www.promare.org.
2011: JAN | FEB | MARCH | APRIL | MAY | JUNE | JULY | AUG | SEPT | OCT | NOV | DEC
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