Watercraft Stealth Technology

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Watercraft Stealth

Technologies


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Stealth ShipA 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 are unique to stealth ships' design.


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Radar cross section (RCS) is a measure of how detectable anobject is with a radar. A larger RCS indicates that an object ismore easily detected.

An object reflects a limited amount of radar energy. A number ofdifferent factors determine how much electromagnetic energyreturns to the source such as:

material of which the target is made;

absolute size of the target;

relative size of the target (in relation to the wavelength of theilluminating radar);

the incident angle (angle at which the radar beam hits aparticular portion of target which depends upon shape of targetand its orientation to the radar source);

reflected angle (angle at which the reflected beam leaves thepart of the target hit, it depends upon incident angle);

Radar Cross Section (RCS)


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In designing a ship with reduced radar signature, the main concernsare radar beams originating near or slightly above the horizon (asseen 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, whichwould perfectly reflect any such beams directly back to the emitter.Retro-reflective right angles are eliminated to avoid causing thecat'seyeeffect. A stealthy ship shape can be achieved by constructing the

hull and superstructure with a series of slightly protruding andretruding surfaces. This design was developed by several Germanshipyards, and is thus extensively applied on ships of the GermanNavy.

Stealth Ship Shaping


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Stealth Ship Examples


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An experimental stealth shipbuilt by Lockheed for theUnited States Navy.

Though the program wasbegun in the mid-1980s but itwas only in 1993-1994, thecraft was revealed to thepublic.

Has only 12 bunks aboard &max it can take 24 at once tosea, it doesn't have muchroom for a large crew.Measuring a bit over 160-feet-long it has one smallmicrowave oven, a

refrigerator & table.

Sea Shadow


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{Designed to elude radar

detection, acoustic detection,

infrared detection & visual

detection, it was the first

stealth ship to enter service.

Carbon fiber reinforced

plastic is used to construct itssurface.

Visby


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The Stiletto, a Twin M hull vessel, is 80

ft in length providing a rectangular area

equivalent to a conventional

displacement craft 160 ft in length. The

vessel's draft fully loaded is 3 ft and isdesigned for a speed of 50-60 kts.

The design and construction of this

vessel made from carbon fiber for

reduced weight and added rigidity.

Largest U.S. Naval vessel built using

carbon fibre composite and epoxybuilding techniques, which yields a very

light, but strong hull.

Has been popular for its efficiency, low

cost, innovation, higher payload fraction,

agility, shock mitigation, shallow draft

and stealth which are the new prioritiesfor the next generation naval craft.

M80 Stiletto


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{Sea Jet, with a length of morethan 133-foot & a full load

displacement of 120 tons

[239,000 pounds] houses a

Rolls Royce Naval Marine

advanced water jet propulsion

system, the AWJ-21, which

improves surface shipefficiency & maneuverability

by reducing noise & wake.

Sea Jet


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It is tall enough to withstand

high sea states, yet foldable so

it can be taken aboard mother

ships and can operate in very

shallow waters," explains a

spokesman for the Lockheed

Martin Maritime Systems &

Sensors division, which is

based in Moorestown, N.J.

The roughly 36-ft.-long craftwould ride on a pair of buoyant

pods. With the pods drawn

inward, CHARC would sit

about 14 ft. above the

waterline. CHARC could avoid

visual, radar and infrared

detection as its water jetpropulsion system speeds it

along at 60 knots.

Charc


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{The currently developed

under DD(X) - is the US

version of a stealth ship.

DDG-1000


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A new range of superfast,

large stealth missile craft,also known as MTBs

(missile torpedo boats).

The word Skjold means

shield in Norwegian. The

flexibility inherent in Skjold

is interesting also to other

navies.

They are among the fastest

warships in the world and

can reach speeds of up to 60

knots / 110 km/t.

Skjold ClassPatrol Boats


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{Its hull form design can

enhance the sea keeping

capability of future small

combatant craft.

Sea Lion


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{It's a stealth look alike,

which has lots of windows,

perhaps a rich & famous

prized possession.

Navy Seals Boat


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Stealth Watercraft List

Braunschweig class corvette

De Zeven Provincin class frigate

Future Dutch Navy offshore patrol

vessels

Rotterdam class amphibious transportdock

F125 class frigate

Type 45 destroyer

Formidable class frigate

Hamina class missile boat

Kolkata Class Destroyer

Kedah class New Generation Patrol

Vessels

La Fayette class frigate

Littoral combat ship

Project 17A class frigate

Shivalik class frigate

Visby class corvette

Type 052C destroyer

Type 054A frigate

Zumwalt class destroyer

Houbei class missile boat Milgems

Tartarstan/Gepard class frigate

Project 21630 Buyan

Project 20380 Steregushchiy

Admiral Grigorovich class frigate

Gorshkov class frigate

Project 21956 destroyer

FREMM multipurpose frigates

Horizon CNGF

Skjold class patrol boat

Sea Shadow (IX-529)

Sachsen class frigate


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Intentional emission of radio frequency signals tointerfere with the operation of a radar by saturating its

receiver with noise or false information.

There are two types of radar jamming:Mechanical

andElectronic jamming.

Radar Jamming


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It is caused by devices which reflect or re-reflect radar

energy back to the radar to produce false target returns

on the operator's scope.

Mechanical jamming devices includechaff, corner

reflectors, and decoys.

Mechanical Jamming


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Madeof different length metallic strips, which reflect different

frequencies, so as to create a large area of false returns in which

a real contact would be difficult to detect.

It is oftenaluminum for weight purposes and is usually coated

with something such as a plastic to make it more slick and less

likely to bind up in large clumps.

Chaff


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Multiple-sided objects that re-radiate radar energymostly back toward its source. An aircraft cannot carry

as many corner reflectors as it can chaff.

Have the same effect as chaff but are physically very

different.

Corner Reflectors


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Maneuverable flying objects intended to deceive a radar

operator into believing that they are actually aircraft.

Dangerous: Can clutter up a radar with false targets

making it easier for an attacker to get within weapons

range and neutralize the radar.

Can be fitted on decoys to make them appear larger than

they are, thus furthering the illusion that a decoy is an

actual aircraft. Some decoys have the capability to

perform electronic jamming or drop chaff. Have a deliberatelysacrificial purpose i.e. defenders may

fire guided missiles at the decoys, thereby depleting

limited stocks of expensive weaponry which might

otherwise have been used against genuine targets.

Decoys


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A form ofElectronic Warfare where jammers radiate

interfering signals toward an enemy's radar, blocking

the receiver with highly concentrated energy signals.

The two main technique styles are noise techniques

and repeater techniques.

The three types ofnoise jamming are spot, sweep,and barrage.

Electronic Jamming


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Occurs when a jammer focuses all of its power on a

single frequency. While this would severely degradethe ability to track on the jammed frequency, a

frequency agile radar would hardly be affected

because the jammer can only jam one frequency.

While multiple jammers could possibly jam a range

of frequencies, this would consume a great deal ofresources to have any effect on a frequency-agile

radar, and would probably still be ineffective.

Spot jamming


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When a jammer's full power is shifted from one

frequency to another.

While this has the advantage of being able to jam

multiple frequencies in quick succession, it does not

affect them all at the same time, and thus limits the

effectiveness of this type of jamming. Although,

depending on the error checking in the device(s) this

can render a wide range of devices effectively

useless.

Sweep Jamming


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Jamming of multiple frequencies at once by a single

jammer.

Advantage: Multiple frequencies can be jammed

simultaneously; however, the jamming effect can be

limited because this requires the jammer to spread its

full power between these frequencies. So the morefrequencies being jammed, the less effectively each is

jammed.

Barrage Jamming


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Class of materials used in stealth technology todisguise a vehicle or structure from radar detection.

RAM cannot perfectly absorb radar at any frequency,but any given composition does have greaterabsorbency at some frequencies than others; there isno one RAM that is suited to absorption of all radarfrequencies.

Can significantly reduce an object's radar cross-sectionin specific radar frequencies, but it does not result in"invisibility" on any frequency. Bad weather maycontribute to deficiencies in stealth capability.

Radar Absorbent Material

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Watercraft Stealth Technology