This is the first good news for India's fast depleting submarine fleet in a long time. The first of the six Scorpene attack submarines being built at Mumbai's Mazagon Docks Ltd (MDL), under transfer of technology from France's DCNS, is now floating in the water.

This is an indication that the delivery of the submarines, delayed by over four years, is finally on track. The revised deadline for the delivery of the first Scorpene to the Indian Navy is September 2016. Thereafter, the delivery of the subsequent five has been promised at the rate of one every nine months.

A submarine is assembled in dry dock. Floating it in water is an indication that it's in an advanced stage of completion. In technical terminology, this marks the "launch" of the submarine.

"Both the pressure and the outer hull of the first Scorpene are in place. Much of the internal fit is also progressing well. The submarine will now be placed on a pontoon, and tugged out of MDL docks to the nearby Indian Navy Dock. This will free one precious submarine-building dock at MDL, and thus help in meeting deadlines for subsequent Scorpenes. The remaining work on the first submarine, in particular the fitment of batteries, will be done in the Naval Dock," a highly-placed source in the Indian Navy disclosed to The Sunday Guardian.

After the fitment is complete in the Naval Dock, the first Scorpene will be put through harbour trials. Once it clears the harbour trials, the boat will head for sea trials, during which its weapons firing capability will also be validated, before finally being inducted as a warship.

The Scorpene is one of the world's most advanced and stealthy diesel-electrical submarines. It will be armed with Exocet missiles and Black Shark torpedoes.

This marks a desperately-needed relief for the Indian Navy, which has lost five submarines in the last 15 years due to decommissioning or phase-out and accident, but not added a single new conventional submarine.

The Sunday Guardian had reported last week the retirement of INS Sindhurakshak, a Kilo class submarine, which suffered a catastrophic on-board explosion, rendering another blow to India's underwater strength. The number of conventional submarines is down to 13, of which three are in life extension refit. Another six are due for similar life extensions. Due to the critically-low force levels, these will be spared only after the Scorpenes start coming in.

A recent CAG performance audit has brought out the desperation. It disclosed that the operational availability of submarines is as low as 50% of those not in elaborate repair or refit.

The only addition to India's underwater fleet in nearly 15 years was a nuclear-powered Akula class attack submarine, codenamed INS Chakra, in 2012. This has been taken on a 10-year lease from Russia.

To maintain minimum numbers of conventional submarines, India embarked on a 30-year programme in 1999 to build 24 submarines. The programme is alarmingly behind schedule. The contract for the Scorpenes, which were to be the first element, was signed in 2005. The first submarine was scheduled to be delivered in 2012, but is now over four years behind schedule. Timeline slippages also led to heavy cost escalation from the initially contracted Rs 18,798 crore to Rs 23,562 crore.

Because of the huge delay in the Scorpenes and then in deciding on a second line of submarines, the Indian Navy has already obtained government approval for converting the requirement for six of the 24 conventional submarines into nuclear-powered ones (SSNs) akin to the leased INS Chakra. This is also significant from the point of view of increasing forays by Chinese nuclear submarines in waters close to India.

These six nuclear submarines will be built indigenously at the strategic Ship Building Complex in Vizag. Unlike a conventional diesel-electric submarine, which needs to resurface after every few days to recharge its batteries, a nuclear submarine can stay submerged for months, giving added stealth, lethality and sea denial capability. Only five other countries besides India have the capability to operate nuclear submarines.

In addition to these attack submarines, both conventional and nuclear, India has laboured for long to indigenously produce a fleet of nuclear-powered, nuclear-missile firing submarines to provide the missing third leg of the triad of nuclear weapons, which can be fired from land, air and under the sea. The first of these, the Arihant, is now undergoing sea trials.