Masking systems in marine vehicle applications work by
reducing radiated noise generated by the vessel’s propulsion
system and general movement. This is achieved by mounting
machined perforations on the sides and propellers of the ship,
through which compressed air is pumped at a high rate. This
action creates a barrier of tiny air bubbles around the vessel
and propellers that traps mechanical noise and disrupts sonar
waves. The result of this is that enemy sonar installations, such
as those found on military submarines, receive a heavily
distorted image of the scanned area, with vessels commonly
shrouded in a pattern akin to rain falling on the ocean surface.What are masking systems?
Mast
A huge faceted radome
encompasses the
antenna-laden central
mast, greatly reducing
its radar cross-section.Sensors
The San Antonio’s passive
electronic warfare system,
SPQ-9B horizon search
radar and long-range air
search radar are also
housed in a signature-
reducing radome.Hull
The hull’s shape is heavily angled and
sports few curved surfaces. These
tailored angulations help massively to
reduce the number of refl ections bounced
back to enemy radar installations.Vehicle decks
Up to 14 expeditionary fi ghting
vehicles and amphibious
assault craft can be carried in
the multi-tiered vehicle decks.RAM coating
The ship is coated in
radar-absorbent material.
This soaks up a percentage
of radio wave energy and
converts it into heat.While the T ype 26, USS
Zumwalt and USS San Antonio
are demonstrating advanced
stealth technologies dedicated
to reducing their cross-sections
to radar, Virginia-class subs are
utilising a piece of kit that can
do the same for sonar. The
Virginia’s ultra-low acoustic
signature comes courtesy of a
special anechoic coating. The
coating, which consists of a
series of sound-absorbent,rubberised panels that sit on
top of the hull work by
dampening electromagnetic
waves, reducing the number
that bounce back and sapping
their overall energy. Adding to
the Virginia’s stealth abilit y is
its revolutionar y pump-jet
propulsion, which works by
drawing water into a turbine-
powered pump via an intake
then pushing it out at the rear,
dramatically muffl ing noise.Virginia-class submarine
- Perforations
Perforations in the hull
allow pressurised air
to be pumped out the
sides of the vessel. - Propellers
Vents in the propellers
also eject air, shrouding
them in tiny bubbles. - Disruption
Noise generated by the propellers and
ship’s movement through the water is
muffl ed, with sonar installations
unable to gain a clear picture.
The
Wraith
The USS Zumwalt – the lead ship in
the upcoming Zumwalt-class of
destroyers – doubles down on the
Type 26’s damage-dealing
capabilities while maintaining a
purist dedication to staying invisible.
Stealth fi rst. Features include an
aluminium/glass-fi bre composite
structure, a wave-piercing hull that
leaves almost no wake and an
exhaust suppressor to reduce its
infrared signature. On top of all this,
a high-angle inward sloping exterior,
noise reduction system and a
trapezoidal, radome-inspired
command and control centre make
this near-15,000-ton titan nothing
but a ghost on radar. This arsenal ofstealth technology
allows it to slip through the waves
like a harpoon, ready to deploy an
arsenal of a much more explosive
nature on unsuspecting targets.
Interestingly, the Zumwalt even
extends its stealth mantra to its
weapons, with every gun, missile
and torpedo launched by integrated
computer systems. As such, far
from crew members having to man
gun emplacements on deck or load
missiles into launchers manually –
generating more noise – the
Zumwalt allows the sleek, minimalist
deck to remain undisturbed, so an
offensive can be launched without
compromising its location.USS Zumwalt
The
Annihilator
© BA E Systems; US Nav yDID YOU KNOW? Sharp edges and angled flat surfaces are better at masking radar signals than rounded ones