INS Khanderi Scorpene-class submarine (image: Hindustan Times)

The Indian Navy has discovered 35 defects along with one “killer defect” in the second Scorpene-class diesel-electric attack submarine, the "INS Khanderi," during its sea trials, pushing its induction by at least one year.

The defense ministry has fully supported the navy’s insistence that Mazagon Dock (MDL) and its technology partner, French warship builder Naval Group, deliver a fully seaworthy and battle-worthy vessel. “The liability of delivering a fully functional submarine is that of Naval Group. If we accept the boat with shortcomings, the liability would be on us,” a senior admiral told Business Standard on Saturday.

The most worrying problem the navy discovered is a killer defect for a submarine: Its engines and propellers were emitting an unduly high level of noise. A submarine's effectiveness and survivability is dependent on its ability to dampen all vibrations it emits, else it gives away its position to the enemy sonar units.

29 of those issues require to be tested when the sea is absolutely calm — or in what is termed “Sea State — 1”. With the monsoon imminent, calm seas are unlikely before September. Four other defects require the submarine be docked in a navy dockyard for testing. This runs up against an existing docking schedule that dockyards have already issued, involving numerous other warships.

The first submarine, INS Kalvari was inducted into service in March of this year. INS Karanj has just begun sea trials, the report added.

These submarines are among the six French-origin Scorpene submarines being built in India, named as the "Kalvari class." The $3.75 Billion (INR 26,205 crore) contract for their licensed production was signed in October 2005 under “Project 75.”

The Navy currently operates 4 German HDW-class submarines and 9 Russian Kilo-class submarines. It had last inducted a conventional diesel-electric submarine, INS Sindhushastra, procured from Russia in July 2000.

Stealth features of the Scorpene submarines include advanced acoustic silencing techniques, low radiated noise levels, hydro-dynamically optimized shape and the ability to launch a crippling attack on the enemy using precision-guided weapons. They can undertake multifarious types of missions such as anti-surface warfare, anti-submarine warfare, intelligence gathering, mine laying, area surveillance etc. India has also approved the acquisition of over 100 heavyweight torpedoes to be equipped on these submarines.