Former navy chief Admiral Sushil Kumar said the incident was, "quite a setback for the navy as Sindhurakshak was one of our frontline submarines which was recently modified and was operational".
But Kumar said that he was confident the navy had ways to find out what went wrong.
"There could be many reasons why it happened; submarines do need a lot of precautions. There are many possible causes for such mishaps, but it is not the first time that such an accident has taken place," Kumar said.
He recalled an incident many years ago when the President had called a board of inquiry, but added that the damage in that case had been contained.
"And, I am sure the navy will have the professional determination to set it right and everything will be back in order," he said.
Vice Admiral (retired) AK Singh said that an internal explosion on a submarine could have been caused either through material failure or because the standard operating procedure was not followed.
In submarines, the batteries are placed in the lower part while on top are the missiles, Singh said.
The batteries release hydrogen and, during charging, the gas reaches a concentration level of about 4 per cent, which may form an explosive mixture.
Singh, however, added that hydrogen alone was not enough to cause an explosion of the magnitude witnessed in the 'Sindhurakshak' case.
"I suspect the hydrogen could have created a fire, which spread to the top where the missile compartments are and reached the warheads, (thus) causing a massive explosion. It is unfortunate it was our frontline submarine. The damage done is enormous," Singh said.
"This is a very major loss. Our conventional submarine fleet has been declining alarmingly and this was a frontline submarine, which had just come from Russia a couple of months back after major repairs and modernisation. It was our most important platform fitted with anti-ship and land attack missiles, torpedoes and very excellent sensors," Vice Admiral Singh said.
He expressed hope that personnel on board the submarine would have survived the mishap.
"All our submarines carry secondary systems of individual escapes, oxygen for two-and-a-half hours, there are enough sets for the entire crew," he said.
Singh said that submarines are divided into six or seven watertight departments in which people can be isolated. People are known to have survived submarine disasters for up to 14 days, he said.
The Sindhurakshak had sunk at the naval dockyard and not at sea, Singh said, adding that, moreover, it had submerged only 2-3 metres, which means that anybody alive could come out.
Singh felt that the submarine itself could be salvaged and there are means of lifting up the vessel. The personnel who are trained for such jobs, too, are there, he said.
Other navies too have faced problems of battery explosions, Singh said, adding that there had been an explosion on a submarine in 1984, although the damages then were not as heavy as in the present case.
"The Indian Navy, I am sure, is capable of getting the submarine back, but if the damage is extensive then it will take some years," he said.
Vice Admiral (retired) Madanjit Singh said that the incident was the first of its kind in the country in peace time and the matter should be seriously investigated.
He said it was possible that the hydrogen that accumulates during the charging of its batteries could have started the initial reaction through a likely spark which then caused the explosion.
"All these weapons have a series of safeguards: inter-locks -- electronic and mechanical -- which prevent the weapons from exploding. So, this is a matter of serious investigation as to what caused this explosion," Madanjit Singh said.
Former Institute for Defence Studies and Analyses director, Commodore (retired) Uday Bhaskar, said that since the rate of induction of new platforms has not kept up with the kind of wear and tear that a submarine faces, the navy's submarine fleet was depleting while its operational load was increasing.
"The fact that the Sindhurakshak (incident) has happened, is going to have its own adverse impact," he averred.
Image: Ships and a submarine belonging to the Indian Navy are seen docked at the naval dockyard in Mumbai ' Photograph: Danish Siddiqui/Reuters
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