16
FORWARD
LOOKING
SONAR
Forward-looking sonar (FLS) is an
underwater technology that employs
sound waves to detect objects and
terrain in front of a vessel or underwater
vehicle. Unlike traditional echosounders
that look down to measure depth, FLS is
oriented to scan the area ahead,
providing a real-time view of what's in the
path.
HOW IT WORKS
FLS operates on the same basic principle as other
sonar systems. It sends out sound pulses and
listens for the echoes that bounce back off
objects. By measuring the time it takes for the
sound to return, it can determine the distance to
the object and create a visual representation of
the underwater environment. This allows for
navigation and obstacle avoidance in low-visibility
conditions.
FEATURE FORWARD LOOKING SONAR
Image of wheel imaged by Water Linked 3D
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EchoPilot FLS
Daniamant’s EchoPilot FLS 3D Forward Looking Sonar is
aimed at private boat owners seeking high performance in
forward-looking sonar technology. This system provides a
precise three-dimensional representation of the seabed
ahead, offering realism and detail to enhance navigation
and safety on the water.
The FLS 3D employs dual transducers to guarantee
comprehensive forward coverage, regardless of hull
shape. With a 60deg horizontal view and a 90deg in the
vertical plane, it delivers one of the widest seabed
perspectives available.
DANIAMANT
TYPES OF FLS
There are several types of FLS, each
with different capabilities:
● 2D Single Beam: This is the most
basic type, similar to a flashlight
beam. It can only detect objects in
the specific direction it's pointed,
providing a limited "keyhole" of
information.
● 2D Scanning Single Beam: This
type physically rotates a single sound
beam to cover a wider area, up to
360 degrees. It creates a complete
picture by piecing together a series
of "slices" from each step in rotation.
This offers high resolution when
static or moving slowly. It's not always
ideal for clarity of moving objects
because it creates a static snapshot
of the environment, causing moving
targets to appear smeared in the
sonar imagery.
● 2D Multibeam: This sonar uses a
wide, fixed beam (typically around
120 deg) that covers a continuous
field of view. It's a solid-state system
with no moving parts, providing a
continuous, real-time update of the
imagery. This makes it more easily
interpretable for use on quick moving
vehicles, although typically will offer
lower resolution than a scanning
sonar when stationary.
● 3D Multibeam: This is the most
advanced type, which creates a
three-dimensional image of the
underwater environment. It works by
"beamforming" in both the
horizontal and vertical directions.
This provides a more comprehensive
view of the terrain and obstacles,
which is particularly useful for
complex environments.
FLS PROVIDERS
18
Sonar imaging technology has undergone
significant advancements in recent years, driven
especially, by the need for improved navigation in
uncrewed systems. One of the most notable is the
integration of 3D imaging capabilities.
Traditional 2D forward-looking sonar provides a flat
representation of the underwater scene ahead of a
vessel, which can be limiting in complex
environments. The option of 3D imaging allows for
a more comprehensive understanding of
underwater topography and potential obstacles,
enhancing situational awareness and decision-
making.
A key attribute of forward-looking sonar is versatility.
Modern systems are designed to be compatible
with a wide range of platforms, from large vessels to
small boats and underwater vehicles.
The integration of artificial intelligence (AI) and
machine learning algorithms represent another leap
forward. These technologies enable sonar systems
to interpret complex sonar data more effectively,
distinguishing between different types of
underwater objects and reducing false positives. AI-
enhanced FLS can learn from previous scans to
improve accuracy over time, making them
invaluable for applications such as underwater
archaeology, where precise identification of objects
is crucial.
Research in this area is ongoing, with studies
exploring the use of self-supervised learning
methods to estimate 3D information from 2D
forward-looking sonar images, further enhancing
the capabilities of FLS systems.
While companies look to enhance the technology,
especially in the large commercial sonars, there are
probably a larger number of applications such the
smaller boat market or entry level/low cost
autonomous vehicles where economics is a greater
driver than technology. Such a system may not
require such an advanced product but simply needs
to know if there is an underwater object that might
endanger the vehicle/vessel.
3D IMAGING
Its forward range extends up to an impressive 200m,
a capability that places it among the most advanced
forward-looking sonar systems on the market,
rivalled only by larger commercial units.
One of the standout features of the Echo Pilot is its
depth-to-range ratio. Boasting a 20:1 ratio, this
technology allows users to see 100m ahead with just
5m of water beneath the vessel. This exceptional
performance ensures safe navigation, even in poorly
charted or uncharted areas, by providing early
warning of underwater hazards and terrain changes.
The system’s real-time sonar updates every second,
ensuring the captain is always informed about the
seabed’s contours and potential hazards. Designed
as a versatile black-box solution, the FLS 3D
integrates seamlessly with any display featuring a
video input. This flexibility allows boat owners to
incorporate the system into their existing
navigational setups with ease.
For Raymarine users, EchoPilot has taken integration
to the next level. By connecting via Raynet, the FLS
3D app becomes accessible directly on Raymarine’s
Axiom displays.
This enables simultaneous viewing of sea charts and
forward-looking sonar in real-time, with the option
for split-screen functionality. The full-colour, three-
dimensional display offers 360deg image rotation
through touch controls, along with a zoom function
for closer examination of the seabed and potential
obstacles.
FEATURE FORWARD LOOKING SONAR
19
20
FarSounder’s advanced 3D forward-looking sonar
technology provides vessels with a real-time
underwater view that enhances situational
awareness. Unlike sonars that offer one or two-
dimensional data, FarSounder’s Argos FLS series
delivers a clear, three-dimensional picture of what
lies ahead.
Established over 20 years ago, the original
motivation was to provide the maritime industry with
a tool to help vessels avoid collisions with
underwater obstacles that cause harmful impacts to
marine life such as whale strikes and oil spills.
“Many sectors of the marine industry travel to
remote places where there is a high risk of unreliable
or non-existent charts,” said a spokesman. “Not only
can Argos help by showing the user the seafloor, but
it can also detect obstacles in the water column such
as whales, coral reefs, ice, shipping containers, and
other debris well in advance. This helps vessels
maintain smooth operations without incident.”
The system also stores bathymetric data everywhere
the vessel travels. This is referred to as Local History
Mapping. When the ship returns to a location, the
software will display the seafloor data collected from
the previous voyage. This feature is extremely useful
for tasks like anchor surveys or route planning.
Users can opt-in to anonymously uploading their
stored bathymetry data to the cloud and receiving
an aggregate map of seafloor data collected by
other Argos users across the FarSounder Fleet.
FarSounder has partnered with global ocean
mapping initiatives like Seabed 2030 allowing
Argos users to make citizen scientific contributions
and improve hydrographic information using the
seafloor data they collect.
One sector, in particular, looking for technology to
provide a solution to navigation safety is Uncrewed
Surface Vessels (USV) and Autonomous Surface
Vessels (ASV).
FarSounder’s Argos 3D FLS plays a critical role in
enhancing the situational awareness and
operational capabilities of these vessels. All Argos
sonars feature a machine interface that enables
intelligent navigation decision-making in real-time
and allows for easy access for remote human-in-
the-loop operators.
The Argos systems do all the data processing. This
provides the vehicle control system with the
information needed to make real-time course
alterations. All Argos Navigation Sonars models
have an Ethernet-based machine interface. USV/
ASV developers can access the same fully
processed information used in display software for
integration with their system via a Software
Development Kit.
FEATURE FORWARD LOOKING SONAR
ARGOS FLS
FAR SOUNDER
Argos Navigarion sonar from Far Sounder
21
MINI GAS/LIQUID
SAMPLING TOOL
HYDRAULIC-OPERATED
Available worldwide from
Ashtead Technology
ashtead-technology.com
Designed to capture gas and liquid
samples in a subsea environment.
The Vortex Hydraulic Mini Gas Sampling tool can
recover samples to the surface in a low pressure state
of no more than 14psi (0.96bar) using a hydraulic,
mechanically operated syringe to ingest samples then
purge sample into a sample container after recovery to
surface. The tool is designed to be deployed from the
surface with the syringe bled of air immediately upon
entering the water and sample fi lling driven by a suck
and blow pumping motion created by the syringe and
associated relief valves. Samples can also be discharged
underwater if necessary.
MINI GA
SAMPLI
HYDRAULI
Ava
Designed to cap
samples in a su
The Vortex Hydraulic M
recover samples to the
of no more than 14psi (
mechanically operated
purge sample into a sam
surface. The tool is des
surface with the syringe
entering the water and
and blow pumping mot
associated relief valves
underwater if necessary
22
Forward looking sonars can help navigate in
complex or uncharted waters - particularly
useful for applications which rely on it for
obstacle avoidance and route optimisation.
The ability to detect rocks, reefs, and
submerged wreckage allow vessels to adjust
their course well in advance, preventing
collisions. This is particularly useful in
environments like harbour approaches and
narrow shipping channels.
The fishing industry employs it to locate fish
populations and monitor aquaculture systems,
while salvage operations use it to find and
assess sunken vessels or cargo. It can support
hydrographic surveys by providing accurate
data for mapping seafloor topography and
assisting in sediment management.
It is used in marine research and environmental
monitoring by enabling detailed mapping of
underwater habitats and tracking marine life. In
defence and security, FLS is employed for
detecting underwater mines, unauthorised
divers, or potential threats near critical
infrastructure, ensuring maritime safety.
It can guide the placement of subsea structures
such as pipelines, cables, and offshore
platforms.
It ensures precision and reduces the risk of
damage to existing infrastructure or sensitive
marine habitats. Search and rescue operations
also benefit from FLS, as it facilitates the rapid
location of submerged objects, wreckage, or
missing individuals, even in murky waters
where traditional optical systems fail.
Forward-looking sonar also enhances
situational awareness during underwater
construction and engineering projects. In
activities such as dredging, pipeline
installation, or subsea infrastructure
maintenance, FLS provides a clear view of the
work area, enabling precise positioning of
equipment and materials.
APPLICATIONS
FEATURE FORWARD LOOKING SONAR
For forward-looking imaging, Impact Subsea offers
its ISS360HD which gives a 1deg acoustic angular
resolution, 2.5mm range resolution and a distance
measurement range in excess of 100m/328 ft. The
sonar is depth rated to 6000m / 19 685ft and comes
in a very compact form factor.
The ISS360HD has a very wide operational acoustic
bandwidth capability; 600 to 900kHz which is fully
utilised through CHIRP (Compressed High Intensity
Radar Pulse) technology. The wide bandwidth linear
CHIRP, combined with Phase Shift Keying and
coding techniques allows for an excellent range
resolution of 2.5mm when using the full bandwidth.
A narrow acoustic beam, combined with a very short
range resolution allows for extremely high definition
imagery to be produced. This makes the ISS360HD
ideal for work class ROV operations with excellent
range capability and ability to identify targets in
zero visibility.
The form factor of the sonar also opens this high
resolution capability up to even the smallest of
observation class ROVs.
In addition to the long range and high resolution
capabilities, the ISS360HD benefits from an
inductively coupled transducer. This means there
are no slip rings within the sonar – so there are no
components to wear out and require periodic
replacement.
The sonar optionally comes with an
integrated pitch and roll sensor,
allowing accurate attitude readings to
be provided. This is a very useful
capability when deploying the
sonar in applications using a
tripod to ensure level
positioning.
The integrated pitch and
roll sensor is also a useful
additional sensor reading for
some underwater vehicles.
ISS360HD
IMPACT SUBSEA
ISS360HD
23
In terms of connectivity, the
ISS360HD benefits from serial
(RS232 and RS485) and also
Ethernet communications.
When using Ethernet, the sonar
has been found to scan up to six
times faster than other, competing
serial-only based sonars.
This provides a significant benefit
when using the sonar for
underwater vehicle obstacle
avoidance purposes.
The ISS360HD operates with the
Impact Subsea seaView V3
software, allowing seamless use
alongside the Impact Subsea
Altimeter, Depth Sensor, AHRS
sensor and FMD system. For those
wishing to use the ISS360HD sonar
with an autonomous underwater
vehicle, a Software Development
Kit is freely available to allow
direct integration of the sonar.
ISS360HD sonar image
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24
The Sonar 3D-15 digitised point
cloud output allows users to
integrate with third party
software for visualisation and to
carry out detailed inspections,
while also allowing creation of
intricate models of both targets
and the underwater terrain.
This enables autonomous
systems to execute complex
decision-making processes.
Shallow water, often
characterised by low visibility
and high turbidity, typically
renders optical cameras
ineffective. While traditional 2D
sonars offer some improvement,
Sonar image and real anchor
3D-15
WATERLINKED
Sonar image
FEATURE FORWARD LOOKING SONAR
25
Sonar 3D-15
they fall short in providing a comprehensive
understanding of the surrounding environment.
The Sonar 3D-15 is at the forefront of underwater
exploration, delivering a clear, three-dimensional
acoustic image that penetrates even the murkiest
of waters.
This technology creates the ability for intuitive
navigation, greatly enhancing the user’s capability
to manoeuvre around obstacles and pinpoint
targets.
The Sonar 3D -15 sets itself apart with its compact
and efficient design, boasting a 300m operational
depth and a mere 0.5 kg in-water weight.
Its small size makes it suitable for an extensive
variety of ROVs, from the smallest to those of larger
scales, and empowering them with the ability to
discern targets in challenging conditions.
Aligning with the Water Linked commitment for
ease of use, the sonar’s Graphical User Interface
(GUI) is designed for accessibility through a web-
based browser, displaying real-time data in a 3D
shaded view.
Simple integration and merging
The user-centric design eliminates the
complexity of software installation, simplifying
the integration process.
Moreover, Water Linked provides access to a
detailed Application Programming Interface
(API) to allow users to merge the sonar image
with third-party software.
ACOUSTIC CORER:
REVOLUTIONARY 3D
SUB-SEABED INSIGHT
Kraken Robotics | Transforming Subsea Intelligence
www.krakenrobotics.com
Providing 3D visualization and live rendered
data, Kraken’s Acoustic Corer identifies
geohazards, stratigraphy, and boulders as
small as 0.2 m, ensuring efficient, risk-free
offshore foundation design and installation.
26
The Echoscope is a new state-of-
the-art real-time 3D sonar system
developed and manufactured by
Coda Octopus since the early
2000s.
It is widely deployed for a wide
range of subsea applications
across commercial, defence, and
research sectors such as marine
construction, offshore energy,
pipeline and cable surveys, bridge
and port inspections, dredging,
and salvage operations—enabling
precise placement, verification,
and monitoring even in zero-
visibility conditions.
In the defence sector, it supports
mine countermeasures, diver
tracking, hull inspections, and Port
and Harbour security, while its
compact variants integrate easily
with ROVs, AUVs, and diver
platforms, making it a versatile
tool for complex underwater tasks.
Unlike traditional sonar systems
such as Side Scan, Multibeam
Echosounders (MBES), or
Multibeam Imaging Sonars (MBIS),
the Echoscope is the only
technology in this group capable
of delivering true real-time 3D
volumetric imaging. It generates a
complete 3D dataset in a single
sonar ping, without relying on
accurate positioning and
mosaicking or combining
multiple frames over time.
To illustrate how these
technologies differ, consider the
analogies (Above)
The Echoscope transforms how
subsea environments are
CODA OCTOPUS
Technology
Analogy
Side Scan
Fax or facsimile image — a flattened
snapshot of the seafloor
MBES
Topographic map — detailed depth
contours without texture
2D MBIS
Top-down video — real-time, but only in 2D
Echoscope PIPE
Real-time 3D Hologram — dynamic,
spatially accurate 3D representation
ECHOSCOPE PIPE NANO GEN SERIES
27
visualized, enabling live 3D
mapping and precise tracking of
underwater operations in ways
that other sonar technologies
cannot.
The Echoscope PIPE series,
introduced in 2020, marked a
significant leap forward in real-
time 3D sonar imaging with the
integration of a high-powered,
extensible parallel processing
engine embedded directly within
the sonar head. This innovation
elevated both imaging
performance and processing
capabilities.
All Echoscope systems have
acquisition, control, and
beamforming internally within the
sonar itself. This architecture
enables the system to process up
to 164 million full time-series
beam sample points per ping, at
rates of up to 60 pings per
second.
Despite the immense volume of
raw acoustic data handled, the
output bandwidth is very
efficient—typically lower than
that of a standard ROV video
feed.
Echoscope PIPE is designed to
produce a wide range of high-
quality real-time sonar outputs
which include multiple dynamic
Sunken Car
28
4D (real-time 3D) volumetric
images, each with different sonar
parameters, filters, field of view and
frequencies, each with up to 65,536
beams per ping; Full Acoustic Time
Series Data (Raw Backscatter) and
hybrid options using our highly
versatile in-built Sequencer
Module.
A key advantage of Echoscope
PIPE technology is its ability to
serve as a single, multi-purpose
sensor, enabling users to
consolidate a wide range of subsea
survey and inspection tasks into
one system. This versatility reduces
operational complexity and
streamlines both equipment
logistics and data workflows.
The Echoscope PIPE also played a
central role in the response to the
Francis Scott Key Bridge collapse,
where it served as the primary
sensor across the entire recovery
and inspection work scope.
Despite the Echoscope PIPE sonar
family expanding to over seven
distinct form factors, each
available in five different depth-
rated variants, the growing
demand for integration with next-
generation small underwater
vehicles—both manned and
unmanned—as well as robotic
platforms and diver-wearable
systems, called for a radical,
ground-up development.
Over the past two years, Coda
Octopus has made a significant
investment in the development of
its’ next-generation custom
technology chipset. This
breakthrough custom chip set
forms the foundation of our latest
NANO Gen Series of sonars
innovation, enabling the
miniaturisation of our industry-
leading real-time 3D imaging
sonar—without compromising the
integrity of our high-performance
channel signal acquisition
architecture.
The newly launched Echoscope
PIPE NANO Gen Series
Propeller Survey
Bridge Inspection
FEATURE FORWARD LOOKING SONAR
29
introduces a breakthrough in
compact sonar technology,
featuring an ultra-small form
factor only slightly larger than a
smartphone or tablet.
Designed for seamless
integration with small underwater
vehicles, diver platforms, and
robotic systems, the NANO Gen
Series brings the power of real-
time 3D sonar to previously
inaccessible applications.
Built on the proven Echoscope
PIPE technology platform, the
NANO Gen Series delivers the
same uncompromising real-time
3D volumetric imaging
performance, now in a
significantly smaller and lighter
package.
Operating across a frequency
range of 420 kHz to 920 kHz, the
system offers an optimal balance
between image resolution and
operational range, with a current
model field of view of up to 54° x
54°.
Weighing just 4.68 kg in water
(for the deep-rated model rated
to 3,000 meters), the NANO Gen
Series sonar also features a wide
input power range (24–48 VDC),
simplifying integration across a
variety of subsea platforms.
Size comparison
Autonomous Underwater Vehicles
www.codaoctopus.com
sales@codaoctopus.com
+44 131 553 1380 / +1 407 735 2400
DEPLOY ANYWHERE. ANYTIME. ANYHOW...
NANO SIZED. MAXIMUM IMPACT
Man Wearable
Remote Operated Vehicles
A Shade Bigger Than A Smartphone
The Echoscope PIPE NANO Gen Series® Sonar packs High-Resolution, Real-Time
3D imaging capabilities into an ultra-compact design, making it the perfect fit for
new generations of underwater vehicles, diver wearable applications and robotics
systems. It delivers exceptional underwater spatial awareness and is a bullet
proof capability for imaging in zero-visibility water conditions - giving operators
confidence and clarity in even the most challenging subsea environments.
30
Teledyne Marine ‘s advanced,
forward-looking sonar (FLS)
systems offers tailored solutions
for various applications.
Underwater navigation is fraught
with challenges—unpredictable
environmental conditions and
hidden obstacles. In regions like
the Arctic, shifting ice floes can
pose significant risks, while
coastal areas with complex
topographies demand
heightened situational
awareness.
Teledyne’s forward-looking
sonar systems address these
challenges by providing high-
resolution, near-real-time
imaging of the underwater
environment, ensuring safer and
more efficient operations.
Unlike downward-facing sonars
that primarily survey the
seafloor, FLS systems focus on
the horizontal plane, making
them indispensable for
detecting obstacles, monitoring
marine environments, and
navigating dynamic or poorly
mapped areas. These
capabilities are crucial for
industries ranging from offshore
energy to defence and scientific
research.
BLUEVIEW SERIES
For precise, close-up imaging
during diving applications, the
BlueView series handheld
systems produce crisp pictures
for hull inspections and
underwater construction.
These sonars are lightweight,
scalable solutions that connect
seamlessly to existing AUVs and
ROV systems.
They are particularly flexible
and ensure reliable operation in
harsh underwater environments.
SEABAT F50 AND 7123
On the other hand, the SeaBat F50
and 7123 are used for longer-
range and better resolution.
The most precise systems the
company offers for imaging for
navigation, search and rescue, and
offshore energy. .
Diver-
mounted
Sonar
FEATURE FORWARD LOOKING SONAR
A BlueView FLS picking up an AUV image
TELEDYNE
31
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