OVERVIEW: The S 4 [Improved Arihant Class] is a nuclear-powered ballistic missile submarine (SSBN) operated by the Indian Navy. It represents a significant evolution of the earlier Arihant-class, incorporating improvements in sensor technology, stealth, and missile payload capacity.

DETAILS: The Improved Arihant-class represents India's continuing efforts to bolster its nuclear triad and enhance its strategic deterrence capabilities. Development of the class likely incorporated lessons learned from the operation of the lead boat, INS Arihant. These improvements are believed to encompass enhanced noise reduction measures, more advanced sonar systems, and the capacity to carry a larger complement of ballistic missiles. The program’s existence underscores India's commitment to maintaining a credible and survivable nuclear deterrent in the face of evolving regional security challenges. The design philosophy prioritizes survivability, incorporating features to reduce the submarine’s acoustic signature and maximize its underwater endurance.

The primary role of the S 4 is to serve as a platform for launching nuclear ballistic missiles, providing a secure and retaliatory second-strike capability. While primarily an SSBN, the Improved Arihant-class likely retains a secondary anti-submarine warfare (ASW) and anti-surface warfare (ASuW) capability, albeit with less emphasis than dedicated attack submarines. The integration of advanced sonar systems such as the Shark Rib [MGK-540 Skat-3], Shark Tail [MG-541 Skat-3], and Shark Gill [MGK-540 Skat-3] arrays provides comprehensive situational awareness, enabling the submarine to detect and track both surface and subsurface contacts at extended ranges. The Porpoise sonar system likely serves as a dedicated active sonar for close-range detection and navigation.

The S 4’s sensor suite enables effective navigation, target detection, and threat assessment. The Snoop Pair [MRKP-59] radar likely provides surface search and navigational capabilities. The Generic Acoustic Intercept system allows the submarine to passively monitor enemy communications and radar emissions. The Mouse Roar [MG-519 Arfa-M] radar warning receiver can detect and classify incoming radar signals, providing early warning of potential threats. The presence of both a Generic Submarine Periscope, Optical, and a Generic Submarine Periscope, LLTV (Low Light Television) offers enhanced visual situational awareness, particularly in low-light conditions. The submarine's armament consists of 533mm torpedo tubes for self-defense and the Improved Arihant VLS (Vertical Launch System), capable of launching K-series ballistic missiles, the centerpiece of the submarine's strategic role. The Signal Ejector system is for countermeasures and communication.

SPECIFICATION: Length: 130.0 m || Beam: 11.0 m || Draft: 15.0 m || Disp: 7000 t

SENSORS: Shark Rib [MGK-540 Skat-3] || Shark Tail [MG-541 Skat-3] || Shark Gill [MGK-540 Skat-3] || Porpoise || Snoop Pair [MRKP-59] || Generic Acoustic Intercept || Mouse Roar [MG-519 Arfa-M] || Generic Submarine Periscope, Optical || Generic Submarine Periscope, LLTV

ARMAMENT: Signal Ejector || 533mm TT || 533mm TT || Improved Arihant VLS