India’s ageing fleet of submarines is matter of concern, since less than half of 14 submarine fleet can actually be deployed; Mazagaon Docks Limited (MDL) which is manufacturing locally Six Scorpene submarines from technology transfer from DCNS of France is already facing delays and first submarine which was under constructions from 2006 will only be delivered in 2015, and the project has gone over budget by 6000 crore.
Indian Navy will issue RFP (Request for Proposal) for a new line of six submarines with AIP (Air Independent Propulsion) capability designated Project 75-I. but the Indian navy has current requirement of around 24 to 30 Fleet of Diesel and Nuclear Submarines. Indian Navy currently operates Russian made Ins Chakra which is a nuclear power attack submarine (SSN) and India is also working on Ins Arihant which is a nuclear power ballistic missile submarine (SSBN).
Ins Arihant which is a 6,000 tonne vessel and an SSBN class submarine is actually much smaller then Ins Chakra which is a 8000 tonne vessel and a SSN submarine, diesel electric submarines are known as SSK class which are tasked for hunter-killer role, but Sea wolf-class Nuclear submarines operated by United states for hunter-killer role have displacement of near 8000 tonne, so Ins Arihant class submarines can be modified into hunter-killer role or SSN if required.
Sources have informed idrw.org that Arihant class can be made into SSN class but Current Naval requirements are development of new bigger SSBN class submarines after all four Arihant class submarines are delivered to Indian navy. India will be manufacturing Diesel submarines under Project 75-I under Technology transfer from the winning bidder, but whole process of RFP and selections and development will take time and considering delays which Scorpene submarines are facing it will be better if second line of Arihant class is started for SSN class submarines.