Stealth ship

USS Zumwalt after floating out of drydock, 28 October 2013

U.S. Navy's Sea Shadow (IX-529)

A stealth ship is a ship which employs stealth technology construction techniques in an effort to ensure that it is harder to detect by one or more of radar, visual, sonar, and infrared methods. These techniques borrow from stealth aircraft technology, although some aspects such as wake and acoustic signature reduction (Acoustic quieting) are unique to stealth ships' design.

Reduction of radar cross-section (RCS), visibility and noise is not unique to stealth ships; visual masking has been employed for over two centuries and RCS reduction traces back to American and Soviet ships of the Cold War. One common feature is the inward-sloping tumblehome hull design that significantly reduces the RCS.

Examples

Several surface vessels employ stealth technology, amongst them the Russian Admiral Gorshkov-class frigate, the Swedish Visby-class corvette, the Dutch Zeven Provinciën-class frigate, the Turkish MİLGEM corvette, the Norwegian Skjold-class patrol boat, the French La Fayette-class frigate, the Chinese Houbei-class missile boat and Type 054 frigate, the German MEKO ships Braunschweig-class corvettes and Sachsen-class frigates, the Indian Shivalik-class frigate, Kolkata-class destroyer, Kamorta-class corvette, the Singaporean Formidable-class frigate, the British Type 45 destroyer, the U.S. Navy's Zumwalt-class destroyer, Finnish Hamina-class missile boats, Chilean Patrol Vessel PZM based on the German OPV80 and Indonesian 63m Stealth Fast Missile Patrol Vessel. Egypt has Ambassador MK III missile boat.

HMS Helsingborg, one of the Swedish Navy's Visby-class corvettes

French frigate Surcouf of the La Fayette class

Dutch destroyer Evertsen of the Zeven Provinciën class

Indian Stealth Frigate INS Shivalik, lead ship of her class

Visby is designed to elude visual detection, radar detection, acoustic detection, and infrared detection. The hull material is a sandwich construction comprising a PVC core with a carbon fibre and vinyl laminate. Avoidance of right angles in the design results in a smaller radar signature, reducing the ship's detection range.

Britain's Type 45 anti-air warfare destroyer has similarities to the Visby class, but is much more conventional, employing traditional steel instead of carbon fibre. Like Visby, its design reduces the use of right angles.

Sea Shadow, which utilizes both tumblehome and SWATH features, was an early U.S. exploration of stealth ship technology.

The currently developed U.S. Zumwalt-class destroyer — or DD(X) — is the US version of a stealth ship. Despite being 40% larger than an Arleigh Burke-class destroyer the radar signature is more akin to a fishing boat, according to a spokesman for Naval Sea Systems Command; sound levels are compared to the Los Angeles-class submarines. The tumblehome hull reduces radar return and the composite material deckhouse also has a low radar return. Water sleeting along the sides, along with passive cool air induction in the mack reduces infrared signature. Overall, the destroyer's angular build makes it "50 times harder to spot on radar than an ordinary destroyer.

The Arleigh Burke-class destroyer also employs stealth technology without being a full stealth ship, similar to the German designs.

German Braunschweig-class corvette

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Russian Admiral Gorshkov-class frigate

Type 45 Royal Navy destroyer

Horizon-class frigate of the French Navy and Italian Navy

Ady Gil, operated by the Sea Shepherd Conservation Society, was painted with what the owners claimed to be radar-absorbent material. Thus, Ady Gil would have been a rare case of a non-military vessel employing stealth technology.

The Indonesian X3K 63m stealth fast missile patrol vessel has a trimaran design with long, but small center hull and has been built from carbon composite materials.

Shaping

Main article: Naval architecture

Detail of the Forbin, a modern frigate of the French navy. The faceted appearance reduces radar cross-section for stealth.

Sloped surface features visible in this frontal view of Hamburg, a Sachsen-class frigate of the German Navy

In designing a ship with reduced radar signature, the main concerns are radar beams originating near or slightly above the horizon (as seen from the ship) coming from distant patrol aircraft, other ships or sea-skimming anti-ship missiles with active radar seekers. Therefore, the shape of the ship avoids vertical surfaces, which would perfectly reflect any such beams directly back to the emitter. Retro-reflective right angles are eliminated to avoid causing the cat's eye effect. A stealthy ship shape can be achieved by constructing the hull and superstructure with a series of slightly protruding and retruding surfaces^{[citation needed]}. This design was developed by several German shipyards, and is thus extensively applied on ships of the German Navy^[specify] .

See also

• Admiral Gorshkov-class frigate
• F125-class frigate
• Steregushchy-class corvette
• Milgem-class corvette
• Kolkata-class destroyer
• Shivalik-class frigate
• Talwar-class frigate
• Kamorta-class corvette
• Brandenburg-class frigate
• Sigma-class corvette
• Sa'ar V-class missile boat
• Valour-class frigate
• ARC Juan Ricardo Oyola Vera
• Infrared signature

References

• "Stealth on the Water" "Mechanical Engineering"

External links

• DDG 1000 information; formerly DD(X)
• Shivalik class frigate
• Stealth ships steam ahead article by Chris Summers on BBC news, 10 June 2004