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Side scan sonar pays off.

Discussion in 'Ideas and Stories' started by james croft, Oct 19, 2012.

  1. james croft

    james croft Solo Diver

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    Below is a story that illustates the advantage of side-scan sonar for recovery operations. Despite a very good last seen point of a child that drowned after accidently sliding into a quarry and sliiping from the grasps of friends it took a side-scan sonar to locate him him after a long search using traditional methods. He ended up being found a considerable distance from the last seen point. This article appeared in the Richmond Times Dispatch in today's paper. :
    Sonar helped find Prince George boy's body in less than 3 hours





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    Credit: FAMILY PHOTO
    Clacy Sullivan, 12, who slipped and fell into the Vulcan Quarry pond while playing with two other boys. Oct. 17, 2012.



    By: Mark Bowes | Richmond Times-Dispatch
    Published: October 19, 2012 Updated: October 19, 2012 - 12:00 AM
    ยป 0 Comments | Post a Comment
    PRINCE GEORGE, Va. -- A team of divers using sonar equipment in an 80-foot deep quarry pond was able to locate the body of a Prince George County boy in less than three hours after being called from a training exercise in a neighboring county.
    After standard diving techniques failed to locate the remains of 12-year-old Clacy Sullivan on Wednesday, a Virginia Department of Game and Inland Fisheries law enforcement dive team got a call at 3:15 p.m. to assist.
    The five-officer squad broke off training at Lake Rawlings, a scuba and camping park in Brunswick County, and headed straight to the Vulcan Materials quarry pond off Puddledock Road in Prince George, where Clacy slipped into murky waters late Tuesday afternoon and drowned. Two friends, 13 and 16, tried unsuccessfully to save him.
    After arriving at 3:58 p.m., it took the officers 178 minutes to locate the boy about 50 yards off shore and in roughly 50 feet of water, authorities said. His body was recovered about 30 minutes later, shortly after on-site vigils for the youth had ended.
    "A lot of times we'll be searching with sonar for days and days," said Sgt. Jon Hart, who directs the Game and Fisheries dive team. "So this one was the exception to the rule. And it's a good thing it was, because in these situations we know very well that it's grueling for the family to see all these things going on.
    "We're just happy we could make it go faster," he added.
    Clacy's body was taken to the state medical examiner's office in Richmond, but police said his death is not suspicious.
    "At this point, we don't have any indications that foul play was involved," said Prince George police Capt. Brian Kei. "We'll be in touch with the medical examiner's office, and if there are any red flags, they will let us know."
    The game and fisheries officers brought their own boat, divers and equipment. To search the quarry's depths, the team deployed a sidescan sonar system that can examine and create images of large swaths of the bottom and detect specific objects in great detail.
    A 4-foot long steel device known as a towfish was lowered into the water and pulled behind the crew's boat as they searched the area where Clacy slipped into the water. The device emits an acoustic pulse and measures the distance from an object that reflects back an echo of the pulse.
    A cable attached to the instrument is connected to a computer screen in the boat, where images of the objects detected under water are displayed.
    "If the conditions are good, and you're getting good pictures back, the amount of detail you can see with those units is amazing," Hart said. "Sometimes those targets are plain as day and you can see exactly what it is."
    When the crew detected what appeared to be a human body at 6:55 p.m. Wednesday, they marked the area on the bottom with a target buoy. A GPS feature on the sonar's software also helped mark the spot. Divers then followed a line tied to the buoy and searched the waters below.
    "And this was one of those fortunate circumstances where we were able to drop the marker, go down approximately 50 feet and we were able to identify that it was (Clacy)," Hart said.
    By using sonar, "you can cover wide stretches in the water looking at a computer screen, rather than sending divers down and putting them in danger and burning tanks of air not knowing exactly what you're looking for," Hart said. "The sonar allows us to be safer, it allows us to be more efficient and it allows us to minimize the time we actually put divers in the water.
    A similar sonar system was used in March 2006 to locate the bodies of two Brandermill teens who drowned in the Swift Creek Reservoir after their canoe capsized. Game and Inland Fisheries officers assisted Chesterfield County Fire & EMS and Virginia State Police divers in that weeklong effort.
    In this week's search, Prince George Fire & EMS was assisted by six other public safety agencies, including the fire departments in Chesterfield, Petersburg, Hopewell and at Fort Lee, the Virginia State Police Aviation Unit and the Crater Regional Technical Rescue Team.
    "You see the victim's family there and you can't fathom what they're going through," Hart said. "Our main mission anytime we go is to do our job as fast and effective as we can, just so they can get some closure. That's what makes us feel good about doing it."






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  2. ReefGuy

    ReefGuy Instructor, Scuba

    # of Dives: 500 - 999
    Location: Punta Gorda, Fl.
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    Ours has become one of the most used tools in our toolbox.
     
  3. abdelhub

    abdelhub Angel Fish

    # of Dives: 500 - 999
    Location: puget sound
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    Same here. Side scan sonar coupled with ROV is one of the best tools we have.

    Mike
     

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