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Navy Contractors Use Smart Tether In Recovery of USS Westfield
Nonacoustic System Monitors Real-Time Tether and Diver Position, Assisting Archaeological Mapping of a Civil War Steame

By Jeremy Frank
President and Co-Founder
KCF Technologies Inc.
State College, Pennsylvania

KCF Smart Tether installed on a diver's umbilical tether with a heading sensor on helmet.
On January 1, 1863, the same day President Abraham Lincoln was issuing his Emancipation Proclamation, the USS Westfield, a steam-powered side-wheel gunboat assigned to defend the harbor at Galveston, Texas, was exploded and sunk by her crew to prevent capture by Confederate forces. Almost 150 years later, a joint effort to document and recover her remains began in the busy shipping channels of Galveston Bay.

The area in which the Westfield sank, at the intersection of the Texas City and Houston shipping channels, is scheduled to be dredged to deepen the shipping lane. To preserve historical artifacts at the site, a joint-dive operation was launched on November 19, 2009, that included the U.S. Navy, the U.S. Army Corps of Engineers, Phoenix International (Houston, Texas), Donjon Marine Co. Inc. (Hillside, New Jersey), PBS&J Corp. (Orlando, Florida) and Texas A&M University.

Poor visibility and strong currents made the search area difficult for divers to navigate, and topside personnel needed to direct divers through the search grid with a high level of accuracy and without disturbing the surrounding area. In addition, archeologists needed to document the exact location of discovered artifacts during diving operations. For these reasons, the operations required a real-time positioning system, and the team chose the KCF Technologies Smart Tether, given its versatility and ease of use.

Smart Tether Technology
The Smart Tether positioning system includes the functionality of a regular tether, but also tracks real-time global positioning system (GPS) information for divers and underwater vehicles, along with advanced scanning, mapping and target-marking functions.

The Smart Tether does this by incorporating several sensor units, or nodes, at fixed locations along the length of the tether. Each node employs a system of sensors that transmit position data through the tether to computer software located topside.

The Smart Tether software interprets the orientation and depth of each node, calculating the position relative to the base point in real time. A built-in mapping and scanning feature makes it easy to quickly process the position data into mission reports.

A diver goes through a final predive check for a preliminary USS Westfield salvage dive.

When dive operations are based on a shore, permanent dock or pier, the base point can be entered as a fixed position.

If the operations are being run from a moving platform, such as a boat or a barge, the software takes the position from a GPS antenna and updates the actual tether position in real time.

In addition to aiding navigation for the diver, the Smart Tether provides tether awareness for the diver's umbilical, which can be critical in avoiding time-consuming or dangerous tether entanglements.

The update rate of the Smart Tether is approximately five times per second, allowing topside personnel to receive real-time information about the diver's position and the orientation of the helmet or camera, making navigation and communication easier and more efficient.

In deeper water, or when operating at a greater distance from the base unit, extension tethers can be added to the system in line with the main tether, allowing greater flexibility in deployment options.

A number of software options can tailor the system for the particular application and allow easy integration with an operator's existing hardware and software systems.

The Smart Tether can also be used with scuba-equipped divers who need accurate positioning data, such as search-and-rescue-units, ship hull inspection teams and salvage divers. Accessories to integrate diver communications, hand-held cameras or sonar units are also available.

The Smart Tether positioning system integrates with remotely operated vehicles (ROVs) as well, particularly with VideoRay (Phoenixville, Pennsylvania) inspection-class ROVs.

Application in Galveston Bay
The operations in Galveston Bay used the Smart Tether in its diver configuration attached to a supply umbilical. KCF Technologies personnel were on hand prior to the start of dive operations to train surveyors and divers from Phoenix International on the use of the Smart Tether positioning system and to supervise the preliminary dives.

In the preliminary stages of the recovery effort, workers used side scan sonar to sweep the area to establish a search grid within which the divers would work.

With the poor visibility and strong currents, the Smart Tether offered a significant advantage over acoustic technology, such as an ultrashort baseline acoustic positioning system, which is sometimes used for similar operations. Acoustic systems can be accurate under ideal conditions, but they can be cumbersome to set up and are subject to data dropouts caused by acoustic noise, reflections and obstructions between the transponders. The Smart Tether does not experience these issues because it is a nonacoustic system, using a combination of orientation and pressure sensors in multiple locations along the tether.

Because recovery operations were based from a barge moored in Galveston Bay, the tides, currents and wave dynamics caused the topside basepoint location to move. The Smart Tether's GPS integration provided constant updates to the basepoint location. This made documenting the absolute position of artifacts, which is critical to maintaining the archeological record of the site, a one-step operation.

The markers recorded by the Smart Tether software can be overlaid directly onto an electronic nautical chart or Google Earth imagery for easy georeferencing, providing a visual reference to nearby landmarks.

The dive operations on the USS Westfield site successfully concluded in mid-December 2009 with the completion of the archeological survey and successful recovery of historic artifacts from the bay floor.

The Conservation Research Laboratory at Texas A&M University has begun the task of cataloging and restoring the large array of artifacts recovered, including the main gun of the Westfield, a nine-inch Dahlgren cannon weighing in at nearly 10,000 pounds.

The precise artifact locations that have been recorded with the help of the Smart Tether positioning system will ensure that the historical value of the site is preserved for future research and study.

Jeremy Frank is the president and co-founder of KCF Technologies Inc., a privately held product development company with focus areas in underwater navigation, wireless sensors and electromechanical systems. He has worked for 12 years on the development and commercialization of innovative solutions centered around piezoelectric materials and vibration and energy harvesting technologies. He earned his Ph.D. in mechanical engineering from Pennsylvania State University in 2001 and his M.B.A. from Pennsylvania State University's World Campus in 2005.

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