Amphibious Squadron of the Indian Navy (IN)
Amphibious vessels fall into two broad categories - those that roll onto the beach and those (typically much larger) that carry landing crafts or hovercrafts in their belly which in turn are disgorged onto the beach. As of now landing ships of various sizes from 200 tonnes to 6000 tonnes are preferred to land men and machines and supplies onto a gently sloping beach due to their carrying capacity. Hovercraft offer greater flexibility of being able to glide over marshes and non-beach but flat coastal areas but at the cost of limited payload carrying capacity and range.
The hull design: Diagramme below is a scale model of the 280 foot long LST [Landing Ship (Tank)] INS Cheetah of the Russian Polnocny class and depicts the wedge shaped hull design of landing ships (when viewed from the side). Hulls of amphibious vessels are broad, shallow with a buff flat bow and without the V shape needed for speed and stability. Hence they are by design slow, typically 12 to 16 knots (~22 to 30 kmph) and poor seaboats i.e. they roll and pitch more than a traditional hull.
Getting onto the beach: When beaching, the ship comes in with ballast tanks partly full keeping it lower and more stable in the water. It is an art to judge what speed to beach at - typically between 2 to 3 knots and when to deploy the stern anchor so that you don’t stop too soon ie in say 9' deep waters or go charging up the beach and damage your propellers and rudders.
Getting off the beach: While discharging its payload of troops, machines and supplies the vessel by definition gets lighter. This creates the risk of the ship beginning to float freely due to bouyancy. You don’t want a 5000 tonne, 400' long vessel afloat loose on a crowded beach swinging around the stern anchor pivot! So while discharging the ship fills in its ballast tanks slowly to make it more stable and to keep it grounded on the beach while unloading. When it's time to go you blow the ballast tanks, let Archimedes' principle do its job and reverse your propellers.
The Magar/Shardul class LST - our mainstay: In the 1980s India decided to build its own landing ships and went for the largest design we had access to. Typically landing ships that can beach are in the 200 to 3000 tonnes range but a British design went up to the 5600 and an American one to the 10,000 tonne range. The British sold us the design of the successful Sir Lancelot class which we modified to our tropical environment and operating protocol and fitted with power plants being license built in India from SEMT Pielstick. The Sir Lancelot or Round Table class was a sound design and the Australians too did what we did - buy the design and build to your specifications. We put 5 into service slowly over 20 years from 1987 - the first two are called the 'Magar' class and the next 3 with improvements the 'Shardul' class.
Kumbhir Class LST (Polnocny class): For all practical purposes our modern amphibious story started in 1966 with the induction of 2 Russian Polnocny class LST (Landing Ship Tank). These were medium sized ships of ~1150 tonnes displacement and could transport and deliver 8 to 10 armoured vehicles and ~150 troops. Between 1966 and 1987 a total of 10 were bought of which 3 called the Kumbhir class are still in service but now long in the tooth. Before 1966 we had one ex-British LST of WW-II vintage but its utility was limited by age.
A new 800 tonne Landing Craft Utility (LCU) is entering service; 6+ are on order. They will replace the Polnocny and the smaller landing ships shown above.
INS Jalashwa - the queen, for now: In 2007 the IN acquired its first ever ship from the US Navy. INS Jalashwa (Hippopotamus in Hindi) is a large amphibious ship capable of fast sailing to the point of attack and then off loading its payload via landing craft and helicopters. The Americans offered us two refitted ships but we took only one despite the attractive price. Those were the days of a certain defence minister known for his inability to take decisions or let anyone else take them. Jalashwa is a 'Austin' class LPD a US/NATO nomenclature meaning Landing Platform Dock. while Jalashwa is a little long in the tooth it could serve us for another 7 years and has given the IN invaluable experience at handling a large amphibious ship.
INS Jalashwa carries certain U.S. restrictions on offensive deployment. Now that India and the U.S. are getting closer as allies this may not be a major issue. The vessel underwent a deep refit in 2012 and received a new upgraded, Indian developed/integrated suite of radars, sensors, action information systems, ECM etc.
The Future: The IN has put out a tender for 4 multi-purpose amphibious assault ships that can carry helicopters and landing craft and a military payload of 6 tanks, 20 armoured vehicles, 40 heavy trucks and operate upto 10 heavy choppers for transport and attack roles. It should have requisite command & communications facility, on-board hospital, repair workshop and other support infrastructure. Fincantieri's rendition of what it could look like.
Amphibious operations are amongst the most complex military operations. It involves the surface fleet, naval carrier aviation, the army (or marines), attack helicopters direct air support and depending on range, the Air Force. Before a beach assault the beach needs to be covered by a reconnaissance mission on depth, slope, underwater obstacles not to enemy mention defences and all this needs to be done discreetly. In today's age of satellite reconnaissance a beach assault would find it difficult to be done with surprise so the attacking forces need to be equipped for a over whelming attack. In terms of complexity of large naval operations amphibious assault comes on top of the list. It is heartening to see the IN developing its capability in this sphere.