India's INS Sindhuvijay Kilo-class diesel-electric submarine will sail for home on August 5 to rejoin the Indian navy after a three-year, €51 million ($80 millon) extensive upgrade, Russia's Zvyozdochka shipyard said.
The overhaul was delayed for six months because of the poor performance of its new SS-N-27 Club-S subsonic cruise missiles which failed to hit their target in six test firings in autumn last year.
The Club-S can be launched either from a 533-mm torpedo-tube or a vertical launch tube. It has a range of 160 nautical miles (220 km) and uses an ARGS-54 active radar seeker and a Glonass satellite and inertial guidance system.
India refused to take delivery of the submarine until all the problems had been solved.
New tests, which ended in mid-July, were successful.
The INS Sindhuvijay is the fourth Indian submarine to be modernised at the Zvyozdochka shipyard.
The Kilo-class submarine, reputed for its supposed quietness, has been bought by Algeria, China, India, Iran, Poland and Romania.