Sonar decoy
![](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/Pillenwerfer.jpg/220px-Pillenwerfer.jpg)
A sonar decoy is a device for decoying sonar. Most are released from submarines to act as a false target.
Submarine decoys
[edit]The first submarine decoys were the German Bold fitted to U-boats of World War II. These were a pellet of calcium hydride in a simple metal container. On contact with sea water, the calcium hydride decomposed to produce a trail of hydrogen gas bubbles that acted as a bubble curtain and reflected ASDIC impulses to produce a false target. The container trapped hydrogen and floated, with a crude spring valve to maintain buoyancy to keep it at a constant depth.
Later decoys, such as Sieglinde, were motorised and could deploy their false target away from the host submarine, increasing safety.
Torpedo decoys
[edit]Decoys were also used by surface ships to decoy the developing acoustic torpedoes. These were usually towed behind the host.
Example decoys
[edit]Bubble decoys
[edit]Reflective bubble targets
Hammer and explosive decoys
[edit]These were intended to swamp the listening device with noise
- Siegmund
Signature decoys
[edit]Towed decoys
[edit]- Foxer, a British towed decoy to decoy acoustic torpedoes away from surface ships. Also used by the US as FXR and the Canadians as CAT.
- T-Mk 6 Fanfare, US development of Foxer
References
[edit]- ^ Gannon, Robert (2009). Hellions of the Deep. Penn State Press. pp. 132–133. ISBN 978-0271038407.
External links
[edit]![](http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
- "Sonar decoys". uboataces.com.