January 2, 2015

How they fired a torpedo & got it back

After several attempts over two days, a team of scientists retrieved a heavyweight torpe do that was buried off Visakhapatnam on the floor of the Bay of Bengal.

The team from National Institute of Ocean Technology (NIOT) and Naval Science and Technology Laboratory , which developed the 1,500kg torpedo `Varunastra', used a ship-borne deep ocean profiler to locate the weapon through sound sig nals after poor weather conditions did not permit to complete the search operation with a remotely operable vehicle.They found the weapon buried in the seabed approximately 21 nautical miles (40 km) from the coast.

The torpedo was pulled out of the sea bed on December 23 by a ship after several failed attempts due to sea currents making it difficult to properly position the vessel and the metal wire the team used to haul it out. The torpedo, carrying vital information for future trials, was lost at sea on November 6 during a technology demonstration trial.

The NIOT team employed the ocean profiler from ocean research vehicle Sagar Nidhi. The scientists said they used the profiler instead of normal sonar because it provided a clearer picture of what was on the seabed. They had earlier surveyed the area with details of the torpedo's probable location provided by NSTL.

The team began the search operation at a depth of around 170 metres and located the torpedo embedded vertically in the seabed at a depth of 168 metres. "Only seven metres of the torpedo was jutting out of the sea bed," said G A Ramadass, head of the Deep Sea Technology Group at NIOT. "It was a challenge to locate the torpedo in the high seas and the current was difficult to handle."

The team faced more hurdles while retrieving the torpedo. It took multiple attempts with a metal wire mesh, with weights fixed to it, strung from the ship before they finally pulled the torpedo out of the sea bed and lifted it out of the water.

"We had to manoeuvre the ship ex actly above the torpedo. The sea current was making it difficult to send down the metal wire to pull up the torpedo," Ra madass said. "The wire was constantly drifting because of the current. We changed the direction of the ship and adjusted the weights on the metal wire several times before we could snare the torpedo." ESSO-NIOT director M A At manand said it was first such opera tion in the country . "No torpedo had been recovered from such a depth in the past," he said.

times of india

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