Scorpene leak: military experts explain why it may not cause much harm

Senior military officers believe the leaked documents do not contain such sensitive details as the sonar signature, which otherwise require enormous effort by the adversary to gather.

"Look, none of the leaked documents is classified above 'restricted'. And information contained in 'restricted' documents is more or less available on the internet. So, if no 'secret' document has been leaked, the danger to us is very little," said Retired Air Marshal Pranob K Barbora.

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A retired vice admiral pointed to what can be described as an "operational safeguard" against the leaks. All navies operating in the Bay of Bengal and the Arabian Sea, he explained, must deal with a peculiar problem. "It's what we call negative gradient water. It means that the temperature drops as the sub goes deeper into the waters. In the process, sound waves from the sub's screws bend away from their actual position, thus misguiding the sonars of the anti-submarine warfare vessels on the surface or even sub-surface."

In naval parlance, propellers are called screws. Sonars of an anti-sub vessel can pick up not only sound made by propellers but also hull popping sounds and even the clinking of glasses in the galley. If these sounds are distorted, say by the negative gradient, they become much more difficult for the "sub killers" to detect.

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