Miniratna DPSU HSL Delivers Nipun: The Systems Behind an Integrated Underwater Platform

The delivery of Nipun, the second Diving Support Vessel (DSV) built by Hindustan Shipyard Limited (HSL), a Miniratna Category-I Defence Public Sector Undertaking (DPSU), to the Indian Navy today offers a useful window into the engineering that goes into building a genuinely multi-mission underwater operations platform. The vessel has been designed and constructed in accordance with the Classification Rules of the Indian Register of Shipping (IRS).

The Acceptance Document (D448) was signed by Rear Admiral Arvind Rawal, VSM, Chief Staff Officer (Technical), Western Naval Command and Chairman of the D448 Committee, and Rear Admiral Chandrasekharan Raghuram, VSM (Retd.), Chairman and Managing Director, HSL — marking the delivery of the class's second hull just a year after the first, INS Nistar.

A Name That Fits Its Purpose

'Nipun' comes from Sanskrit, meaning one who is adept, capable, and well versed in a particular discipline. In keeping with this name, the ship is a highly specialised vessel, built to undertake Deep Sea Dive Operations and Rescue Operations at Sea.

Hull and Displacement

Nipun measures 118 metres in length and displaces over 8,560 tonnes, with more than 80 percent indigenous content by value. That scale gives the platform the stability and payload capacity required to carry the specialised systems a modern DSV demands, without compromising on the sea-keeping needed for sustained deep-water operations.

Dynamic Positioning

Central to the ship's operational profile is its Dynamic Positioning (DP) system, which uses thrusters and positioning references to hold the vessel precisely over a work site without relying on anchors — essential when operating above a dive site or during a submarine rescue attempt, where even small drift can endanger divers or rescue equipment below.

Saturation Diving Systems

Nipun's saturation diving capability allows divers to be maintained at working-depth pressure for extended periods, avoiding the cumulative decompression time that repeated surface transits would otherwise require. This is typically supported by diving compression chambers, hyperbaric life-support systems, and a means of transferring divers under pressure — infrastructure that turns the ship into a self-contained platform for extended deep-sea work rather than a simple transport vessel. The ship is fitted with state-of-the-art Dive Equipment enabling this Deep Sea Saturation Diving capability, and a Side Diving Stage has also been provided to support diving operations.

Submarine Rescue Integration

The vessel's Submarine Rescue capability builds on the same underlying philosophy as its sister ship, INS Nistar: functioning as a mother ship for a Deep Submergence Rescue Vehicle (DSRV), managing its launch, recovery, and communication link while the DSRV attempts to reach a disabled submarine and evacuate personnel. Few navies operate this complete chain — vessel, DSRV and trained crew — as an integrated, organically owned system.

Deep-Sea Intervention

Beyond diving and rescue, Nipun's deep-sea intervention systems extend its working envelope for tasks such as underwater inspection, light salvage, and equipment recovery — capability typically delivered through Remotely Operated Vehicles (ROVs) that can operate beyond diver depth limits. These ROVs further enhance the ship's operational capabilities by facilitating Diver Monitoring and Deep Sea Salvage Operations.

An Indigenous Build Base

HSL has previously indicated that the programme drew on around 120 Micro, Small and Medium Enterprises (MSMEs) across its supply chain to reach its stated indigenisation figure — a distributed vendor base that had to meet naval-grade certification standards across a wide range of specialised components.

Hindustan Shipyard Limited is a Miniratna Defence Public Sector Undertaking (DPSU) under the Ministry of Defence, based in Visakhapatnam, with a shipbuilding history of more than eight decades and a portfolio that includes submarine construction and refit work.