Torpedo defence

Torpedo defence includes evasive maneuvers, passive defense like torpedo belts, torpedo nets, torpedo bulges, and sonar torpedo sensors, "soft-kill" active countermeasures like sonar decoys and sonar jammers, and "hard-kill" active defenses, like anti-torpedo torpedoes similar in idea to missile defense systems. ^[1] Surface Ship Torpedo Defense and Countermeasure Anti-Torpedo systems are highly experimental and the US Navy ended trials on them in 2018. ^[2]

Examples of Countermeasure Anti-Torpedo (CAT) Systems

Soft-Kill Countermeasures

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Soft-kill torpedo countermeasures include a variety of decoys and jammers designed to deceive or disrupt the tracking systems of acoustic torpedoes. These countermeasures can be towed, stationary, or self-propelled, and typically rely on acoustic signals, magnetic signatures, or bubble screens to mislead incoming weapons. E.g.

• Bubble decoys: Create reflective noise via chemical or gas discharge (e.g., Bold, Sieglinde).
• Sonar jammers: Saturate acoustic sensors with disruptive noise (e.g., Siegmund, ADC).
• Signature decoys: Simulate ship acoustics or magnetic fields to lure torpedoes away (e.g., Foxer, Nixie, Maareech, MG-series).
• Mobile/swimming decoys: Self-propelled, often reusable systems simulating ship movement (e.g., Rafael's SCUTTER Mk 3, Mobile Submarine Simulator).
• Integrated systems: Combine sensors, jammers, and decoys in one suite (e.g., Leonardo C30/S, Ultra SSTD, Rafael's Torbuster).

Hard-kill Countermeasures

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Hard Kill Countermeasure anti-Torpedo (CAT) systems are generally divided into two categories: Antitorpedo Mines (ATM) and Anti-Torpedo-Torpedoes (ATT). Both types rely on Torpedo Detection, Classification, and Localization (TDCL) systems to identify incoming threats. E.g.

Torpedo Detection, Classification and Localisation (TDCL):

• Ultra Electronics DCL Technology Demonstrator programme
• Surface Ship Torpedo Defence
• Rafael's BlackFish/MonkFish HMS (DSIT) ^[3]

Anti-Torpedo-Torpedo (ATT) systems:

• Rafael's TORBUSTER a fourth-generation torpedo defense countermeasure developed by Rafael Advanced Defense Systems. Designed to neutralize incoming torpedoes in both shallow and deep water, it combines soft- and hard-kill capabilities. ^[4]
• The U.S. Navy’s Countermeasure Anti-Torpedo Torpedo (CAT), developed by Penn State’s Applied Research Laboratory. The CAT system was designed to counter wake-homing torpedoes, which detect a ship’s wake rather than its acoustic signature. The CAT torpedo operates autonomously after launch with “fire-and-forget” capability, using onboard sensors to search, target, and maneuver against threats. Developed under a high-priority program, CAT was produced within 24 months through extensive simulation-based design and modular construction, reducing costs significantly compared to legacy torpedoes. It was first deployed aboard the USS George H.W. Bush in 2013 and subsequently installed on additional vessels. ^{[5] [6]}
• The SeaSpider ATT system by ATLAS ELEKTRONIK has undergone successful live-fire trials. These tests involved detection and localization of incoming Mk 37-derived autonomous underwater vehicles (AUVs) and DM2A3 torpedoes using passive and active TDCL sonar systems. Upon detection, the SeaSpider interceptor was launched from an above-water launcher to intercept threats at their closest point of approach, with successful intercepts confirmed through acoustic and optical means. ^[7]

Antitorpedo Mines (ATM)

• ATM systems are considered a low-cost, broad-spectrum defense solution. These systems deploy neutrally buoyant mines into a ship’s stern wake, where they maintain depth and detect incoming torpedoes using acoustic and magnetic sensors. The mines then detonate to disrupt torpedoes following predictable paths. ^[8]
• In addition, the RBU-1000 anti-submarine rocket launcher is alleged to have anti-torpedo capability.

See also

• AN/SLQ-25 Nixie – sonar decoy that fakes passive, active and wake-homing returns

References

1. Sprenger, Sebastian (16 April 2019). "Navies, companies push for torpedo-killing torpedoes". Defense News . Retrieved 17 April 2019.
2. Director, Operational Test and EvaluationFY 2018 Annual Report (PDF). Department of Defense. p. 163. Retrieved 22 April 2019.
3. "Comprehensive Integrated torpedo defense" (PDF). rafael.co.il.
4. "TORBUSTER" (PDF). rafael.co.il.
5. Winner, Cherie (August 22, 2017). "Fire and forget: How do you stop a torpedo? With a better torpedo". psu.edu. Retrieved 2025-08-05.
6. La Grone, Sam (June 27, 2013) [June 20, 2013]. "Navy Develops Torpedo Killing Torpedo". news.usni.org. Retrieved 2025-08-05.
7. "Successful Sea Trials for Atlas Elektronik' SeaSpider Anti-Torpedo System". navalnews.com.
8. Lieutenant Conners, Lieutenant Matthew (November 2021). "A Hard-Kill Solution to Threat Torpedoes". usni.org.