My last post was dedicated to the brave Indian sailor Cdr Abhilash Tomy of Indian Navy. His boat “Thuriya” had rolled over and dis-masted in stormy seas in the South Indian Ocean. The officer was injured and confined to his bunk in his boat till he was rescued by the French fisheries research vessel “Osiris” . Indian Navy had deployed a P8-I maritime surveillance aircraft to locate him and a frigate INS Satpura to recover him from Amsterdam island where he was being treated.
INS Satpura is a Shivalik Class frigate of the Indian Navy. This is a class of 3 ships in commission with a total of 12 of the type planned to be inducted. These ships are multi-purpose stealth frigates which have been designed in India by the Naval Design Bureau and built by the Mazagaon Docks Ltd (MDL) at Mumbai. These ships were conceived in 1998 and ordered in 1999. All three ships of the class, INS Shivalik, INS Satpura and INS Sahyadri were in service by July 2012. These ships have been named after hill ranges in India.
These ships use a CODOG configuration of engines to turn their two shafts. CODOG means, Combined Diesel or Gas Turbine. What this means is that each shaft of the ship – to which a propeller is attached which moves the ship – has two engines. A diesel engine and a Gas Turbine engine. The diesel engines are used for cruising and slow speed operations while the Gas Turbines are used for high speed chases. At a time, either the diesel engines or the Gas Turbines can be used. This requires a complex gearbox arrangement. In case of the Shivalik Class the gearbox was designed by an Indian company Elecon Engineering of Mumbai. These ships displace 6,200 tons at full load. They are 142.5 m (468 ft) long, 16.9 m (55 ft) wide and have a draught of 4.5 m (15 ft). Draught is the portion of the ship’s hull under water. So this ship extends 4.5 m below the water. They have two Pielstick 16 PA6 STC Diesel engines which produce a combined 15,200 SHP at 1,084 rpm. While in boost mode, two General Electric LM 2500 Gas Turbine produce a combined output of 33,600 SHP 3,600 rpm. With diesel engines alone, these ships can cruise at a maximum speed of 22 knots (40 km/h) and with Gas Turbines they can reach a maximum speed of 32 knots (58 km/h). These ships have a range of 5,000 nautical miles (9000 km at 18 knots speed).
The Shivalik Class is armed with Indian, Russian and Israeli radars, Indian sonars, Indian decoys and Indian weapons control system. They are armed with one Italian 76 mm Oto Melara Naval Gun and two Russian AK 630 closed in weapon system guns. They carry two twin DTA-53-956 torpedo launchers and two Russian RBU 6000 anti submarine rocket launchers. They carry either eight Russian vertically launched Klub anti ship missiles or eight indigenous Brahmos anti ship and land attack missiles. For anti air protection they carry 24 Russian medium range Shtil missiles and 32 Israeli short range vertically launched Barak missiles. In addition, these ships also carry two HAL Dhruv or Seaking Mark 42B. They have a ships crew of 257 including 35 officers.
These ships are classified as stealth ships because they use several measures for reducing signatures of the ship which may be used by enemy sensors to detect them The signature reducing efforts start with the hull shape which is designed with odd angles to minimise the radar reflection and thus the radar signature. They have machinery mounted on vibration mounts and cradles to reduce the sound signature, which is the main signature used by submarines to detect a ship. Also, several design features have been included to cool down the exhaust of the engines before it is released, thus reducing the thermal signature used by missiles to lock onto targets.
The follow-on of Shivalik Class is called the Project-17A, 7 of these ships are on order at MDL and Garden Reach Shipbuilders and Engineers, Kolkata.