India has only 10 conventional submarines, when it needs 24.
Indian submarines, on an average, are available for just six out of 10 days for operational deployment. And of every 10 tasks allotted to the fleet, it has to drop at least one, a senior Naval officer told NDTV.
India needs at least 24 conventional submarines but only has 10 - which includes a nuclear submarine leased from Russia in 2002. The last conventional submarine was acquired in the late '90s. Each conventional boat in the fleet is around 20 years old.
In contrast, China has 60 -- 48 conventional and 12 nuclear submarines. Pakistan has five submarines and is acquiring 8 Shang class submarines from China.
The depletion of submarine fleet isn't the Navy's only cause of concern.
"We have major issues with spare parts that reduces availability of platforms," the officer told NDTV. India's efforts to reverse engineer spares have been successful, "but it is not perfect," the officer said.
"The aging fleet means that the stress to run the boat is more and leaves the crew with less and less time for critical tasks," the officers added.
Submarines are critical for "sea-denial" - refusing the enemy space to navigate and dominate the sea. Indian Navy's charter spreads over a vast mass of water stretching from Gulf of Aden in the West to the Straits of Malacca in the South.
In 1999, the government had approved a 30-year submarine building programme. The plan proposed building six submarines in India by 2012 and six more by 2030.
But although India signed up with French Weapons manufacturer DCNS to acquire six Scorpene Disel-Electric attack submarines in 2005, the process has been delayed by half a decade.
The first boat - INS Kalvari, being built in Mumbai's Mazagon Dock - will be out for sea trial this year and is expected to join the Navy in late 2016.
The plan to build six more submarines under the "Make in India" programme is yet to take off. South Block is yet to decide which shipyard should be given the contract.