Analysis: How Russia’s Innovative Submarine Coating Reduces Detection Risks.

The Russian Ministry of Defense initiated a significant modernization program in 2022 to upgrade the hydroacoustic coatings of its nuclear-powered submarines. This effort aims to improve the stealth capabilities of these vessels, enabling them to evade detection more effectively. The new coating reduces the acoustic signature of the submarines by suppressing noises generated by the vessels and external sonar signals.
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Keel-laying ceremony of Project 677 Lada submarines Vologda and Yaroslavl. (Picture source: bmpd)

The hydroacoustic coating is made up of specialized plates, each weighing up to 80 kilograms. These plates are composed of multiple pressed layers of advanced rubber materials and feature unique channels designed for acoustic performance. They are affixed to the submarine's lightweight hull using an adhesive with a classified composition. Once attached, the plates are coated with paint to ensure durability and optimal performance.

Each nuclear-powered submarine requires approximately 10,000 of these plates, meticulously installed to create an effective barrier against enemy sonar detection.

The stringent testing process for the new hydroacoustic coating was recently showcased on the Russian television program Voennaya Priyomka (Military Acceptance) aired on the Zvezda channel. The tests, conducted at the Sevmash shipyard—Russia’s premier submarine manufacturing facility—demonstrated the robustness of the adhesive bonding the plates to the hull.

The testing procedure begins with a drill featuring a cup-shaped bit, which is lubricated with soapy water and used to bore into the rubber coating. A metal corkscrew is then inserted into the resulting hole and pulled out using a specialized device that measures the force required to dislodge it. Results show that the adhesive can withstand a force of over 4.5 kN (kilonewtons), confirming its exceptional strength.

To ensure minimal impact on the coating’s acoustic properties, the hole is sealed with a fast-curing sealant, rendering it virtually undetectable. This rigorous process is applied to every tenth plate, meaning approximately 1,000 plates are tested before a submarine undergoes state trials.

The upgraded hydroacoustic coating is expected to enhance the operational effectiveness of Russia’s nuclear submarine fleet. By reducing detectability, these submarines will have a greater edge in strategic missions, such as patrolling and covert operations, particularly in contested waters.

In contrast, the United States has long utilized lightweight synthetic polymer tiles on its Virginia-class and Ohio-class submarines. These tiles are engineered to absorb sonar waves effectively while maintaining a reduced thickness to minimize weight and hydrodynamic drag. The U.S. approach integrates these coatings with other noise-reduction technologies, such as pump-jet propulsion systems, to create a multi-layered stealth system. However, issues with long-term adhesive durability have been reported, which may compromise performance over extended periods.

China has focused its efforts on developing composite rubber and polymer coatings for its Type 093B Shang-class submarines. These coatings aim to absorb a broad range of sonar frequencies, enhancing stealth in the Indo-Pacific region. Recent reports suggest that China is transitioning to modular panels for easier maintenance, but the overall robustness and longevity of these systems appear to lag behind those of Russian and American technologies.

Germany, representing NATO’s expertise in stealth coatings, employs advanced rubberized materials on its Type 212 and Type 214 diesel-electric submarines. These coatings are optimized for smaller, non-nuclear platforms and are used in conjunction with Air-Independent Propulsion systems to achieve near-silent operation. While highly effective for their intended platforms, these coatings are less scalable to the larger nuclear submarines operated by Russia and the U.S.