Stealth ship

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. Though radar cross-section (RCS) reduction is a fairly new concept many other forms of masking a ship have existed for centuries or even millennia.

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. Furthermore, round shapes on the ship are eliminated or covered up, examples include smokestacks and gun turrets. Also cavities that present a horizontal face are to be eliminated since they act like a trap and are very visible to radar. To get around these limitations many ships use features such as panels that cover reflective surfaces or use alternate designs of hardware. Also every effort must be made to have the smallest gaps on the ship as possible. Common hull shapes include tumblehome hull designs which slope inward from the waterline, and SWATHhulls which allow for better stability when using a tumblehome hull. These RCS design principles were developed by several navies independently in the 1980s using work done on aircraft RCS reduction as the starting point.

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