The following are excerpts from an article from Nuclear Threat Initiative. The article provides some details about India's Submarine types, capabilities and objectives.
India Current Capabilities - Updated October 2010
"The Indian Navy currently operates 16 submarines, which are based at Visakhapatnam on the east coast and Mumbai on the west coast. An additional west-coast base is also being constructed at Karwar.
[- Ther backbone of the fleet is formed by ten Kilo-class Type 877EM - or Sindhugosh-class - units that are being progressively retrofitted to accommodate the Klub/3M-54E Alfa cruise missile system.
- India also operates four Shishumar-class Type 209/1500 vessels designed by ...HDW.
- two aging Foxtrot-class boats, which are currently being used for training purposes.
- In addition to the 16 active submarines, however, India is also
- in the process of constructing six Scorpène-class boats that are being indigenously built at the Mazagon Dock in Mumbai, albeit under the supervision of French technicians.
- India expects to float a tender on six more diesel submarines within the next year...requests for information are already believed to have been issued to DCNS, for additional Scorpenes; HDW in Germany, for the Type 214; Russia for the Amur 1650; and Spain's Nevantia for the S-80A.]...WHOLE ARTICLE"
The wide range of foreign sourced submarines (Russian and western) certainly reflects India's evolutionary non-aligned status.
Reasons for the wide selection probably also reflect political motivations - not just the search for subs with the best performance at the time.
Wide selection probably also reflects India aim to transfer technology to its ATV project. The more foreign designs and testbeds (including Nerpa/Chakra) the better.
However wide selection also brings with it technical and managerial inefficiencies, leading to delays and cost overruns.
A special problem for India is the Straits of Malacca and other narrow waters obstructing Indian submarine access to China. India may well be restricted to the short-medium range K-15 as its SLBM for 20 years. Placing China's northeasterly major cities in SLBM range may require Indian submarine positioning in the South China Sea or Western Pacific. Chinese submarines, including China's more advanced (than India) SSNs, may block the narrow straits to China. China may also have deployed under-water sensing (SOSUS type) arrays in these straits - warning of Indian submarines approaching. [Seabed or thethered sensing is even more opaque a subject than the daily movements and confrontations of submarines in the oceans around us!] All this may mean Indian submarines may need to get in adequate range of China by moving through relatively open waters via the southern Indian Ocean-south around Australia's Southern Ocean-South Pacific to China. This long voyage (if unrefueled) would require nuclear endurance - one reason for India's interest in SSBNs and SSNs.
"Invalid" commented on January 31, 2011 3:47:00 AM
"SOSUS networks in Straits of Malacca is useless or not feasible because of heavy traffic in there to generate enough noise in the straits for a sub to sneak in."
At 16.50 January 31, 2011 concening possible capabilities of Integrated Undersea Surveillance Systems (IUSS) Pete commented
You appear to have fairly determined views. What is your database?
Modern digital equipment permits descrimination between ship, submarine and natural sounds. Such equipment can also filter out much distortion/noise.
However sound/sonic sensing is just a small part of the spectrum of sensors (probably) available to seapowers and their allies. It is significant that the US no longer describes its network as merely "SOSUS" - rather the broader term Integrated Undersea Surveillance System (IUSS) has been more recently used.
[If one looks at the sophistication of visual spectrum networks, for example closed circuit TV (CCTV) in Beijing or London, one can get an idea of the network centric possibilities of IUSS. CCTV can detect a particular face amongst millions and follow that person across a city.] In addition to sound IUSS may well include visual spectrum, nightvision, magnetic anomoly, active sonar, infrared sesors, robotic undersea vehicles used to follow slower SSKs in particular and pressure/ripple sensors.
Undersea sensors would be just one component of a sensor network against submarines which for India would include "spy" satellites, sigint ground stations, surface ships, SSKs, aircraft and tracking information from allies (possibly the US, Russia and Singapore etc). If a Chinese SSN entered the Indian Ocean all these sensors and alliances would watch and probably handover intensively. [Information sharing may well occur amongst those countries that see China as a potential threat.]
The funneling dictated by the geography of the Strait of Malacca would assist in triggering or "scripting" the many sensor platforms available.