New Delhi, Feb. 14: With the navy having contracted a US-based firm to salvage its submarine that sank last August in Mumbai, the defence establishment is now watching the technology that will play out in the Western Naval Command to recover the boat.
The last major submarine-recovery operation was that of the Russian nuclear boat, the K-141 Kursk that sank in the Barents Sea in the year 2000. The Kursk was recovered nearly a year later from 130 metres below the surface by a conglomerate of companies led by a Dutch firm.
The Kursk was a much larger boat than India’s INS Sindhurakshak that sank at the South Breakwaterin Mumbai’s naval dockyard on August 14 in just about eight metres of water killing 18 of its crew.
It is suspected that a torpedo in the weapons compartment of the submarine exploded. The cause is yet to be precisely determined.
“Every such operation is unique,” said a naval officer. The US firm that has been contracted for about Rs 240 crore is the Resolve Marine Group that also has an Indian subsidiary.
The navy requires that the INS Sindhurakshak be preferably recovered “even-keel” — meaning with its right side up — and in one piece, lifted and be dry-docked. The salvage team will also have to clear the wreck of the submarine of unexploded ordnance.
“We assess that in six months the dangers of the unexploded ordnance — whatever is left — have probably been neutralised by the seawater but one can never be too sure,” said the officer.
Even before the salvagers have figured out how to pull out the Sindhurakshak, an understanding of what exactly happened to the boat would involve, broadly, four stages:
Breaking it free of the bottom: The Sindhurakshak has settled on the bed of the sea and its keel has buried itself into the seabed for about half a metre. The salvagers have to ensure that it comes unstuck. In effect, they have to devise a mechanism to prise out the 3,000-tonne submarine ensuring that in the process it does not tip over. The navy and the salvagers will have to look at de-watering technologies to make the submarine buoyant for this purpose.
Surfacing: The salvagers will then have to steady the boat and work on making it buoyant. This could involve welding hooks into its hull; then pass cables through the hooks to pull it to the surface. Alternatively, to make it buoyant, they may also fix slings around the hull. The salvagers could consider attaching pontoons to the submarine. The pontoons — buoyant devices for flotation — may have to be fashioned in a way that they can be “saddled” to the hull.
Lifting: This could involve both the attachment of the pontoons and pulling with cables attached to cranes that will have to be erected over the boat and spaced in such a manner that the wreck does not break, bend or twist. After it has been surfaced, it would have to be pulled free of the water and transported and placed in a dry-dock.
Assessment: It is in the dry-dock that investigators would be expected to comb through the wreck to determine what happened.
At every stage of the process the salvagers would have to take a call on whether to bring out the wreck in one piece — as the navy would prefer — or break it into compartments. That decision will be taken on the “integrity” of the hull. The explosions are reported to have twisted both the hull and the compartments in the innards of the Sindhurakshak.
Apart from the technological challenges involved in going through this entire process, one of the most difficult issues is the lack of visibility underwater in the naval dockyard. Navy divers have reported that just about a foot below the surface the water is so dark they are near-blind. The divers had to feel their way through the submarine in recovering the bodies — and their parts — of the 18 crew who were killed on August 14 when the Sindhurakshak went down.
In bringing up the Sindhurakshak’s wreck, every “dive” will be decided after checking tidal conditions. The actual lifting will also factor in wave motion. But in the waters of the dockyard that may not be a big factor.
The salvagers have told the navy that it would take at least 45 days to bring in the equipment they think the recovery will involve. Simultaneously, the divers and specialists from the company will be familiarised in detail with the EKM (Kilo)-class submarines in the naval fleet.
This has security compulsions that the navy is wary of. But the salvagers must know each and every compartment of the class of submarines to be able to “feel” their way about and through the wreck of the Sindhurakshak.
Apart from familiarising with the class of submarines that the Sindhurakshak belonged to, the salvagers will also “rehearse” the operation with a mock-up. The technology to be used will be determined through detailed computer simulation. The navy is reluctant to hazard a guess on how long it might take. After insistent questions one officer said it could take three to four months.