A destroyer costing thousands of crores can defend the open ocean brilliantly and still be useless a few kilometres from shore - its hull simply draws too much water to chase a submarine hiding in the shallows near a harbour. That blind spot is exactly what INS Malvan was built to close.

Why the Navy's Biggest Ships Can't Do This Job Picture a

destroyer trying to hunt a submarine hiding a few kilometres off a harbour. It can't get close. Its hull sits too deep in the water - draw a warship into shallow, cluttered coastal water and you risk running it aground before you ever find the target you're chasing. That's not a hypothetical weakness; it's a basic property of how big ships are built and it's exactly the gap INS Malvan exists to close.

The Mechanism: Why Shallow Water Beats Big Ships

Anti-submarine warfare works by listening - sonar systems that need a clean, predictable underwater environment to distinguish a submarine's signature from background noise. In the deep open ocean, that's manageable. In the littoral zone - the shallow water near the coast - the acoustic environment turns messy: currents, seabed clutter, fishing traffic and shifting depth all scramble the signal a large warship's sonar is trying to read.

A destroyer built for blue-water operations isn't just too deep-hulled for this zone; it's carrying sonar tuned for a different kind of listening entirely. What you actually need is a smaller, shallow-draught vessel purpose-built to operate and listen in exactly this messy, close-to-shore environment.

That's the entire reason the ASW-SWC class exists.

Where India Stands: From Gap to Fleet

For years, this capability sat with just four ageing Abhay-class corvettes - Soviet-origin vessels decommissioned between 2017 and 2025, leaving a real window where India's littoral zones had no dedicated submarine-hunting platform at all.

INS Malvan is the second of eight Mahe-class ships now filling that window, part of a 16-vessel programme split between Cochin Shipyard and GRSE, Kolkata - and built with over 80 percent indigenous content, which matters because it means India isn't dependent on a foreign supply chain to maintain or expand this specific capability.

The timing sharpens the picture. Pakistan's acquisition of Chinese-built Hangor-class submarines, equipped with air-independent propulsion that lets them stay submerged far longer than older diesel-electric boats, is exactly the kind of quiet, hard-to-track threat this fleet is designed to counter.

A submarine that can loiter silently near a coastline for extended periods is a threat that has to be found in shallow water, close to shore - precisely where India's blue-water destroyers are least effective and where the ASW-SWC fleet is built to operate instead.

That division of labour is the real strategic point: by handing the littoral-zone job to sixteen purpose-built shallow-water hunters, the Navy frees its larger, capital-intensive warships to focus on power projection across the wider Indo-Pacific instead of babysitting the coastline.

For an aspirant, the exam-relevant insight isn't "India commissioned a new ship"

• it's that maritime security architecture works by matching the right platform to the right depth of water and India spent a decade building the platform it was missing.