Blueprint Subsea StarFish User guide

StarFish Sidescan Sonar
Hull-Mounted System Manual

StarFish Hull-Mounted
System Manual
2
Contents
1. Introduction................................................................................................................................................................... 3
2. Getting Started .............................................................................................................................................................. 4
2.1. What Your System Contains.................................................................................................................................. 4
2.2. Quick Start.............................................................................................................................................................. 4
3. Setting Up The System.................................................................................................................................................. 5
3.1. Choosing A Power Supply ..................................................................................................................................... 5
3.2. DC Power ................................................................................................................................................................ 5
3.3. AC (Mains) Power ................................................................................................................................................... 5
3.4. Connecting The Components ............................................................................................................................... 6
3.5. Choosing A Mounting Location............................................................................................................................. 7
3.6. Mounting The Sonar Transducer.......................................................................................................................... 9
4. Operating the Sonar.................................................................................................................................................... 10
5. Understanding Sidescan Imagery.............................................................................................................................. 11
5.1. What Is A Side-Scan Sonar?................................................................................................................................. 11
5.2. What Does A Side-Scan Sonar Image Look Like? .............................................................................................. 12
5.3. Calculating Depth Below The Sonar (Altitude).................................................................................................. 12
5.4. Calculating The Distance To A Target ................................................................................................................ 13
5.5. Acoustic Shadows................................................................................................................................................ 13
5.6. Reflected Target Intensity................................................................................................................................... 14
5.7. Example Side-Scan Sonar Images...................................................................................................................... 15
5.8. Gain & Contrast Settings ..................................................................................................................................... 16
5.9. Shallow Water & Channels .................................................................................................................................. 16
5.10. Tips For Good Imagery ...................................................................................................................................... 17
6. Safety............................................................................................................................................................................ 18
6.1. Electrical Safety.................................................................................................................................................... 18
6.2. Operational Safety............................................................................................................................................... 18
6.3. Other Precautions................................................................................................................................................ 18
7. Care Of Your Starfish ................................................................................................................................................... 19
7.1. Operational Care.................................................................................................................................................. 19
7.2. Maintenance & Cleaning...................................................................................................................................... 19
7.3. Storage................................................................................................................................................................. 19
8. Troubleshooting.......................................................................................................................................................... 20
9. Product Support.......................................................................................................................................................... 21
10. Limited Warranty Policy............................................................................................................................................ 22
11. Notices........................................................................................................................................................................ 23
12. Specifications............................................................................................................................................................. 24
13. Index........................................................................................................................................................................... 27

StarFish Hull-Mounted
System Manual
3
1. Introduction
Thank you for purchasing your hull-mounted StarFish Seabed Imaging System, a revolutionary high definition
hull-mounted side-scan sonar system which produces near photographic quality sonar images of the seabed.
Whether surveying lakes, rivers or the open ocean for dive sites, submerged structures, shipwrecks or research
purposes, StarFish gives you the capability to capture detailed images of the seabed for work or play, making hi-
tech seabed imaging accessible to anyone. With StarFish the seabed is your playground…
Simply fix the StarFish side-scan sonar transducer to the hull of a vessel, large or small, to capture real-time digital
images of the seafloor below. StarFish is truly 'Plug and Play' connecting to any Microsoft®Windows®based PC or
laptop via a USB connection.
The simple intuitive StarFish “Scanline” software makes seabed imaging extremely easy for novices and
experienced side scan sonar users alike.
Before proceeding, we recommend that you read the safety, installation and operation guidelines in this user
guide, in order to get full benefit from the features of the StarFish system.
We hope you get many years of trouble free use from your StarFish sonar. However, should you have any
difficulties please refer to the “Product Support” section at the end of this manual for details on how to obtain
technical support, upgrades and repairs.
Safety
Before installing and using this product, please read through the “Safety” section at the rear of this manual.
Throughout the documentation the following symbols are used to indicate special precautions or procedures:
WARNING!
This symbol indicates a warning you should follow to avoid bodily injury or damage to your equipment.
CAUTION
This symbol denotes precautions and procedures you should follow to avoid damage to your equipment.
NOTE
This symbol denotes special instructions or tips that should help you get the best performance from your system.

StarFish Hull-Mounted
System Manual
4
2. Getting Started
2.1. What Your System Contains
Before proceeding, please check that your StarFish system box contains the following items…
•StarFish hull-mount sonar transducer head (with supplied cable).
•StarFish transducer hull mounting bracket.
•StarFish sonar top-box electronics module.
•AC to DC universal power adapter (and international plug adaptors).
•DC power lead –cigar plug (fused) to 2.1mm plug.
•DC power lead –cigar socket to crocodile clips.
•USB 2.0 Cable (type-A to type-B connectors).
•StarFish “Scanline” software and drivers USB Drive.
•User Guides.
•Bag of tools & sundries
o5 M625mm stainless steel button-head screws,
o1 4mm Allen key
You will also need…
•Microsoft Windows 7/8/10 compatible computer (or laptop), with 1 free USB port (minimum).
•Battery (for DC operation) or suitably protected AC mains outlet (see page 5).
Additionally, you may also require…
•10mm spanner for adjusting the angle transducer on the hull mounting bracket.
•Suitable fasteners to attach the mounting bracket to the hull of your vessel.
•Clips to secure the transducer cable to the hull of your vessel.
2.2. Quick Start
To get started straight away, you can use the accompanying “Quick Start” guide to get up-and-scanning, or read
on for further detailed operational instructions and tips.
For further details on installing and operating the “Scanline” software package, please refer to the “StarFish
Scanline Software User Guide” booklet.
Note: Do not connect the sonar USB electronics to the PC until the “Scanline” software and drivers have
been installed –this will simplify the installation procedure.

StarFish Hull-Mounted
System Manual
5
3. Setting Up The System
3.1. Choosing A Power Supply
Before setting up your StarFish system, you first need to decide on the power source you will use –either…
•A DC supply (such as a battery or boat electrical system), or
•Mains from the universal AC-DC adapter included with the system.
While the StarFish has internal voltage and current protection circuitry, any DC supply you use should be
externally fused with a quick blow fuse rated at 1A.
For best performance of the StarFish, you should ensure any power source is “clean”, meaning it is free from
electrical noise possibly caused by mains-inverters, electrical motors or any other similar “high-current
switching” devices.
Additionally, for DC supplies, the source should be a fully regulated and smoothed power source –a dedicated
battery is ideal for this.
3.2. DC Power
In marine conditions, where there is a high chance of equipment getting wet, the use of a low-voltage DC power
supply is always recommended.
The StarFish electronics module has a 2.1mm DC input socket that will accept voltages between 9V and 28V, and
will require a supply capable of delivering 5W. Typically this means the StarFish will require just under 500mA at
12V, or just under 250mA at 24V.
As DC supplies come in many varieties, several adaptor cables have been included with your StarFish.
•Use the “Cigar-Plug to 2.1mm cable” to connect your StarFish to either a 12V or 24V system. The plug
itself can be disassembled to access the fuse inside it.
•Use the “Crocodile-clips to Cigar-Socket” adapter cable, for connecting to battery terminals, or other
similar power sources.
If you are making your own wiring loom for the StarFish, you should ensure that the centre pin of the StarFish
power connector is the positive DC voltage, and the outer connection of the plug is ground (or negative).
3.3. AC (Mains) Power
The AC power adapter is included for situations where the electronics will be used in a protected and dry
environment (such as a boat wheel-house), and where a suitably fused and protected mains supply is available.
•The AC adaptor will accept voltage in the range of 100V to 240V AC, and 47Hz to 63Hz.
•Four universal adaptor plates are supplied with the power supply, allowing it to be used in most countries.
When using the AC (mains) power supply, remember that electricity and water do not mix.
To avoid electrical shock, you should only use the AC supply in a dry and enclosed environment, such as a
cabin on board a boat.
Ensure the supply has suitable protection such as quick-trip circuit breakers and an RCD.
Only handle the StarFish equipment with dry hands.

StarFish Hull-Mounted
System Manual
6
3.4. Connecting The Components
Having chosen your power source, the next step is to connect the components of the StarFish system.
If this is the first time you’re using the StarFish system, it is recommended you install the “Scanline” software and
USB hardware drivers on your laptop/PC before connecting the electronics module to it. Refer to the
accompanying “Scanline User Guide” for details on how to do this.
Once the “Scanline” software and drivers are installed, make the following connections…
If possible, turn off the power supply –if this is not possible, make the power connection last.
1. Connect the StarFish sonar transducer head to the
“top box” electronics module, with the 6-way round
connector.
2. Connect the electronics module to a USB port on the
laptop/PC using the supplied USB lead (type-A
connector to type-B).
3. Connect DC power to the electronics module with the
2.1mm power jack –this may be from a DC source, or
the included AC-DC adapter. Follow the selection and
safety guidelines in the “Choosing A Power Supply”
section above.
4. Finally, once you are happy with the connections,
turn on the power.
When powered up, the “Power/Status Indicator” will illuminate and flash – indicating that the Topside box is ready
for use.
When the sonar is ‘pinging’ (transmitting and receiving), the “Activity Indicator” will flash.

StarFish Hull-Mounted
System Manual
7
3.5. Choosing A Mounting Location
Before you can start using the hull-mounted Starfish Sonar system in the field, you will need to mount the sonar
transducer to the hull of you boat. Correct mounting of the sonar is essential in order to achieve the best image
results, and as each hull is different you should consider the following points when deciding on a suitable
mounting location…
Avoid creating acoustic shadows
The hull mounted StarFish transducer has transmitter and receiver elements located on either side of the
moulding that are angled 30° down from the horizontal, and acoustically transmit sound in a “fan beam” of narrow
width (refer to the specification of your StarFish product for the exact width), but wide vertically, with most of the
acoustic energy confined to the centre 60° of the beam.
The arrangement allows the StarFish to perform well in shallow water at long ranges, and see almost directly
below it, but incorrect placement onthe hull could cause “acoustic shadows” or “reflections” to be produced from
the hull, keel or rudder.
In this position, mounted directly on the hull, the keel is
casting a shadow on the starboard channel
In this position, mounted on the keel, no other parts of
the hull are obstructing the acoustic beams.
Acoustic shadows will create blind spots in the sonar’s field of vision and may reduce its maximum working range.
Reflections from the hull may create a ‘ghost’ or mirror image of the opposite channel on the sonar display.
Reduce vulnerability to grounding
When mounting the sonar on your vessel, make sure there is always a point on the hull that is lower than the
transducerslocation. Thiswill reduce the risk of damage to the transducer should you run aground or collidewith
any submerged obstacle.
In this position, the transducer is vulnerable to
submerged hazards
Above, the keel at the centre of the boat is lower than
at the stern, and offers protection to the transducer.
Position in relation to the vessels propeller
Ideally the StarFish transducer should be mounted to the vessels hull in front of the vessels propeller, as this
introduces small air-bubbles into the water which in-turn act as reflectors of sound and degrade the range and
quality of the sonar imagery.

StarFish Hull-Mounted
System Manual
8
If using an outboard motor to propel and steer your boat, ensure that the propeller does not touch the
transducer when the steering is at its extremities.
Try and keep a minimum distance of 400mm between the transducer and propeller to minimise mechanical
interference (noise).
If it is not possible to mount the transducer in front of the propeller, efforts should instead be made to mount the
transducer lower than it, such that its turbulence does not obstruct the acoustic beams.
Avoid cavitation & turbulence
When mounting the transducer onto the hull of your boat, it is important that a location is chosen that under
normal conditions is known to be free from turbulence and aeration. You should also ensure the transducer is
angled such that cavitation and turbulence is minimised on the transmitter and receiver surfaces as this may
distort or degrade the sonar imagery. The figures below illustrate this principle…
Transducer is angled up.
Transducer is level.
Transducer is angled slightly down.
Avoid mounting the transducer behind features on the hull of your vessel (such as rivets, strakes or steps) that
may introduce cavitation or turbulence into the water.

StarFish Hull-Mounted
System Manual
9
3.6. Mounting The Sonar Transducer
You may choose to mount the sonar transducer directly to the hull or keel of your boat (following the
recommendations discussed previously), although where possible wewould recommendthe use of the additional
mounting bracket and the following procedure…
1. Secure the top part of the bracket to a flat
surface on the hull or keel of you boat, using
screws, bolts or other fixings depending on
its construction.
2. Pass the transducer cable through the hole
between the two halves of the mounting
bracket. Ensure you have enough slack cable
to allow the bracket to pivot freely without
the cable becoming taught.
3. Using a 10mm spanner, tighten the bolts on
the hinge of the bracket to fix the mounting
angle of the transducer.
4. Using the 4mm Allen key included, secure
the black moulded transducer assembly to
the underside of the mounting bracket.
The label on the transducer indicates the
front (and hence port and starboard
channels).
5. Use small cable clips to secure the remainder of cable to the hull of the boat and prevent it fouling on
any other equipment.
When attaching the sonar transducer, mounting bracket or cable to the boat, choose a suitable locationand
fixing such that the watertight nature of the hull is not compromised! If in doubt, please contact the
manufacturer of your vessel.
The cable length on the transducer may be increased up to a maximum of 20 metres using a “twin, screened,
twisted pair” cable. Contact StarFish technical support for details of available extension cables.
When routing the transducer cable…
•Try to avoid running it parallel and in close proximity to other high-current cables, radio antenna cables
or anything else that may be a source of electrical interference.
•Do not bend the cable to a radius less than 30mm as this may shorten its life.
•Do not use a fixing method that may cut, damage or excessively crush the cable.

StarFish Hull-Mounted
System Manual
10
4. Operating the Sonar
To summarise, your system should be connected in a similar configuration to the figure shown below, and once
you’ve installed sonar transducer on the hull (or other suitable mounting bracket) as described previously, you’re
ready to run the “Scanline” software, and start collecting data…
Refer to the separate “Scanline User Guide” for information on installing, starting and operating the software.
Operating the sonar is relatively straightforward, but there are a few guidelines and precautions you should
observe to achieve the best results…
•Keep the boat speed constant, and ideally between 1 and 4 knots for the best results. At slower speeds
more display lines will be acquired for smaller targets (giving a higher resolution image).
•Be aware of hazards to navigation and the sonar transducer. The sonar transducer head will only show
you the depth of the seabed below it, not from the surface, and not in front of it. So, if you are scanning
in close proximity to the seabed, you should be keeping a close eye on the sonar display.
•If in doubt of the underwaterterrain or possible hazards, always assume the worst case, and give plenty
of clearance between the sonar transducer and the seabed.
Please be aware that you should not rely on the sonar as a primary navigational aid for your vessel, or for
avoiding shallows, submerged or mid-water hazards.
When the “Scanline” software is running, the “Activity Indicator” will flash to show that the StarFish is scanning
and acquiring data.
See the following section on interpreting side-scan imagery, for further details on calculating the sonar’s altitude
from the displayed data.

StarFish Hull-Mounted
System Manual
11
5. Understanding Sidescan Imagery
Interpreting side-scan imagery mayseem difficult at first, but with practice and some knowledge of how the sonar
works, it doesn’t take very long for an operator to understand what the seafloor is doing below the sonar, and if
there are any targets on it.
Many people try to look at the pictures and understand them as you would a photograph, but this however is not
strictly the case. In the following sections, we will look at several example images, and see how information can
be obtained from them.
5.1. What Is A Side-Scan Sonar?
Sonar (SOund Navigation And Ranging) and echo-sounding technology dates back to the 1920’s, but it was only
in the early 1960's that Dr. Harold Edgerton (an electrical engineering professor at the Massachusetts Institute of
Technology) startedto adapt his techniques on high-speed flash photography to acoustics, having concluded that
photography was not best suited to the murky conditions underwater.
By sending "flashes" of acoustic energy into the water and recording the echoes,Edgerton (who later worked with
underwater explorer Jacques Cousteau), developed a towed side-looking sonar that could create a continuous
image of the seafloor.
By transmitting a narrow fan-shaped acoustic pulse (ping) perpendicular to its direction of travel, the side-scan
sonar sends acoustic pulses outwards. The seabed and other objects reflect some of the sound energy back in the
direction of the sonar (known as backscatter), and the travel time of the returned pulse is recorded together with
its intensity.
As sounds travels at a known velocity (of approximately 1500 metres per second) through water, we can directly
relate the time we received an echo, to the range of the target that reflected it.
This scan-line of information is sent to a topside computer for interpretation and display, and by stitching
together data from successive pulses, a long continuous image of the seafloor is created as the sonar is moved by
the survey vessel.
As mentioned previously, your StarFish has two transducers (transmitter
and receiver elements) that are angled 30° down from the horizontal, and
acoustically transmit sound in a “fan beam” of narrow width (refer to the
specification of your StarFish product for the exact width), but wide
vertically with most of the acoustic energy confined to the centre 60° of
the beam.
This gives the StarFish the ability to see almost directly below it, to just
above the horizontal.
However, despite this field of vision, the StarFish cannot determine where a target lies vertically in its beam (i.e.
above or below it), as everything is translated to a planar 2D display.
For example, if there are two targets both 10 metres from the sonar (one horizontally level with it, and one directly
below it, and are received on the same channel) they would both appear at the same point on the sonar display,
as the display scale is based around time, and both echoes would arrive simultaneously.
With some experience though, image artefacts like “acoustic shadows” can help the operator make an educated
guess to the size of targets and sea-bed features.

StarFish Hull-Mounted
System Manual
12
5.2. What Does A Side-Scan Sonar Image Look Like?
The figure below is a real image captured by a StarFish sonar, where each horizontal line is a representation of
time versusthe intensity of the reflected echoes. The further something isaway from the centre line of the display,
means the longer it took for the echo to be received.
In this figure, both the port (left) and starboard (right) channels are operating at the same time. The sonar is
positioned in the middle of the topmost line, and as the sonar is moved through the water the image will scroll
away from it as more data is added.
5.3. Calculating Depth Below The Sonar (Altitude)
A useful measure to know when using a side-scan sonar is the height above the seafloor, so a safe distance can be
maintained and hazards avoided.
Looking at the previous image, we can see a large black “hour-glass” shaped area in the middle of the display,
where no echoes have been received.
This area is showing us the height the sonar is above the sea bed.
As the figure opposite shows, the nearest object to the sonar will
always be the seabed below it (assuming a relatively flat seabed).
However, it will take some time for the “bottom echo” to be
returned,and as the display shows the receivedechoes fromwhen
the transmission started, this area appears black.
Therefore, the narrower the band of black is, the closer the sonar is to the seabed –and as the image is built up
over time, if the sonar’s altitude changes we start to see the profile of the seabed that the sonar has passed over.
This means in the figure above, the seabed gets shallower in the middle of the display,and then gets deeper again
at the bottom.
h

StarFish Hull-Mounted
System Manual
13
5.4. Calculating The Distance To A Target
As mentioned earlier, the sonar display shows the recorded echoes over a period of time, and we have seen how
we can work out the depth below the sonar from this.
However, this also means that the range a target appears to be on
the display is not the distance it lies at from the sonar horizontally
across the seabed.
To understand why this is the case, consider the triangle shown in
the figure opposite.
As the sound waves travel from the sonar, they start to hit the
seabed, and each point of contact returns an echo along the
shortest path to the sonar.
To work out the actual distance at which a target lies, you need to use the mathematical formula (based on
Pythagoras’s theorem) …
22 HeightRangeDisplayedRangeActual 
5.5. Acoustic Shadows
When sound from the sonar hits a submerged target with any
height above the seabed, an acoustic shadow will be cast away
from the sonar.
An experienced sonar operator can use the lengths of these
shadows, along with knowledge of the sonar altitude to get an
idea of the size and height of the object.
To help understand this, imagine you are in a darkened room, with a flashlight, standing above a ball. If you shine
the flashlight down on the ball, a small shadow is cast around it, while if you lie down level with the ball and shine
the light at it, a much longer shadow is produced stretching away from it.
This principle applies to side-scan sonar in a similar way; objects directly beneath the sonar will appear to have
very small shadows, while objects at greater distances will have longer shadows because they are being
illuminated (acoustically) on their side.
Displayed
Range
Height
Actual Range
Acoustic Shadow

StarFish Hull-Mounted
System Manual
14
5.6. Reflected Target Intensity
To complete our understanding of the basics of sonar imagery, we need to consider the brightness information
(intensity of echo) shown on the sonar display.
As with a surface reflecting light, different surface textures and materials of targets have different acoustic
reflective properties.
Typically, the more the density of the target differs from that of water, or the more rigid its material is, the more
sound is reflected back.
•Any target with a gas in (such as air) will act as an almost perfect reflector for sound, and will show as
the brightest colour in the palette.
•Muddy or silted lake and sea beds will generally show up as a low-intensity background colour, as mud
is a good sound absorber and contains water.
The example image below shows several bright targets of interest…
Taking what we already know about sonar imagery into account we can interpret the following…
•White ‘dots’, without any form of shadow are most likely either flat hard targets on the bottom or large
mid-water fish (with their air-filled swim-bladder showing up on the sonar).
•At the bottom of the image we can see a bait-ball of fish –identifiable as large spherical structure that
protrudes above the seabed profile (there is a faint and fragmented shadow extending away from it,
implying it is not a single solid target).
•On the right of the image, we can see several vertical curved white lines. These are most likely the hulls
of moored boats, and close to them we can see the square outlines of the concrete mooring blocks.
•At the top of the image, there is a large target.As it appears on both channels, and we can see its profile,
we know the sonar has passed directly over it. The bright geometric echoes on it indicate it is probably
man-made, and there is an acoustic shadow visible on the right portion of it, showing it has height.
It is most likely this is the wreck of a sunken vessel.

StarFish Hull-Mounted
System Manual
15
5.7. Example Side-Scan Sonar Images
Lake Bed
Scan showing boat moorings at the bottom (concrete
blocks in craters of silt).
The dark area on the left channel is the shoreline.
A boat with wake is visible on the right.
At the top of the right channel, it can be seen that the
bottom has a rockier texture, and appears brighter
than the silt in the rest of the image.
Cable Car Ferry
Lake bed beneath a cable-hauled car ferry.
The two cables are visible above the bottom, crossing
beneath the sonar.
The movement of the cables has exposed the bedrock
of the lake, causing a brighter reflection.
The grooves are visible on the centre profile on the
lakebed, and the shore and slip-way are visible in the
top left.
Marina
Shallow water with moored boats. The bright white
targets of the hulls are visible, above “craters” in the
silt, caused by the movement of the mooring cables.
Note the large acoustic shadow on the left channel,
caused by a raised area of the seabed being almost
level with the sonar in the shallow water.
Coral Reef
Horizontal image orientation showing a scan over
coral reefs.
At the extreme right of this image, ripples in the sand
are visible, while each coral outcrop has clearly visible
shadows.
Note how close the sonar came to a small outcrop at
the centre of the image!

StarFish Hull-Mounted
System Manual
16
5.8. Gain & Contrast Settings
When operating your sonar, the adjustments you will make to the gain and contrast controls are critical in
achieving good side-scan imagery. This section examines the function and purpose of these controls…
Gain
The software gain control is similar to the volume control on a home hi-fi system, or the brightness control on a
television.
The gaincontrol sets how the incoming scan-lines of data (from the sonar hardware) map onto the display’s colour
palette.
•Increasing the gain value will make all areas of the display image appear brighter, while decreasing it
will make the whole image appear darker.
•For general operation, a gain value of 30% (-28dB) is recommended.
Contrast
The function of the contrast control is slightly more complex to understand than that of the gain control.
The contrast value sets the palette range that the incoming signal will be stretched or shrunk to fit.
•A lower contrast value means that the image will transition from dark to bright colours more quickly
than a higher contrast value.
•For general operation, a contrast value of 30% (38dB) is recommended, but can be reduced to 25% to
enhance shadows and submerged targets.
The best way to understand the operation of the Gain and Contrast controls is to experiment with these values
while scanning the sonar over a known area of seabed.
Generally, having set the operational range of the sonar, you should then set the gain to a level where the
background noise is just visible. This should ensure that quiet signals are visible at the extremities of the display,
whilst the central mid-water areas and seabed profile have good definition.
Then, when scanning, adjust the contrast to give the desired sharpness of targets –lowering the contrast will
make echoes appear brighter, while keeping shadows dark.
5.9. Shallow Water & Channels
When operating in shallow water and channels, you may experience a “ghosting” effect caused by acoustic
returns from previous sonar “pings” still bouncing between targets and the sonar receivers.
To reduce these effects, use a larger “range” on the sonar display, which should have the effect of slowing the
“ping rate” and allowing time for these echoes to dissipate.
In shallow water, you may also see distortion on long range
targets, caused by “multi-path” phenomenon – where sound is
reflected between the seabed and surface before hitting the
target.
Due to surface waves and chop, the effect can manifest its self as
ripples on distant targets.

StarFish Hull-Mounted
System Manual
17
5.10. Tips For Good Imagery
Vessel Speed
When using the StarFish, remember that it is “pinging” at a fixed rate (depending on range). The faster you move
the sonar through the water the more compressed images will appear on the display.
For long ranges, try to travel at speeds between 1 and 3 knots, while shorter ranges can be used with speeds of 3
to 6 knots.
Water Depth
The depth of water beneath the sonar is an important factor to consider when interpreting heights of submerged
objects from their acoustic shadows. In shallow water acoustic shadows from targets appear very elongated (like
shadows cast from objects at sunset), while in deep water the seabed will appear more as a “birds-eye” type view
with minimal shadows.
Mounting Position
The position and method of mounting the transducers on the hull is probably one of the biggest factors in
determining overall image quality. As discussed in previous sections, the transmitter and receiver faces on the
transducer should…
•Have no obstructions in their acoustic beams that may cause shadows or reflections.
•Be clear of any turbulence or cavitation from the hull in front of them.
•Be clear of turbulence or aeration caused by the vessels propeller.
Boat Navigation
When surveying an area, think about the course you will steer your vessel over. Try to divide the area into a grid
of long straight runs, with 180° turns at the end.
Remember that as the boat turns, the acoustic beams from the inside of the turn will overlap, while the outside
ones will be covering more seabed –consequently the imagery produced will appear distorted and hard to
interpret in these areas.
Give plenty of clearance between your boat and other vessels or surface/mid-water hazards, and try and avoid
the aerated water left in the wake of otherboats, as thiswillbe acoustically visible forsome time shouldyou cross
through it with your sonar.
Waves, Wake and Surface Chop
As your StarFish is operating close to the surface, its imagery may be distorted by the motion of the boat due to
waves and surface chop on the water, or it may receive reflections from these at longer ranges.
Consequently, your StarFish will not perform well in rough stormy conditions.
Remember, that when in a boat, your own safety is paramount and should not be compromised trying to
achieve good sonar imagery.

StarFish Hull-Mounted
System Manual
18
6. Safety
6.1. Electrical Safety
The AC power adaptor and surface control box are NOT protected against the ingress of water, so take care to
avoid exposing the unit to sources of conductive liquids. Dry wet hands before handling the AC power adaptor or
surface control box.
•Do not attempt to disassemble or service this product yourself (outside the scope described in this
manual). Contact StarFish technical support for any maintenance, spares or repair work required.
•Do not overload a mains supply outlet, extension cord or adapter as this may result in electric fire or
shock.
•Do not modify the power cord or plug.
•Do not place the AC adaptor or power cord near any heat sources that may melt the protective
insulation.
•Do not use this product if any of the cabling, or housings of its component parts appear to be damaged
or compromised for the ingress of water.
•Do not use (and ensure the product is unplugged) in situations where a power-line surge may occur
(such as a lightning storm), or if the product is not used for a prolonged period of time.
•Ensure that the power supply has suitable earthing, and electrical shock risk is minimised through the
use of fusing and residual-current-detection (RCD) devices.
6.2. Operational Safety
•Do not rely on the product to necessarily represent the immediate sub-surface conditions below the
boat, and as such this product should not be used as a direct means of avoiding submerged objects,
shallow water & grounding, collisions with other vessels, boat damage or personal injury. If you are in
doubt about any of these hazards, always operate your boat and sonar at reduced speeds, and proceed
with caution.
•Do not rely on this product as a navigational aid.
•Do not allow the sonar transducer cable to obstruct or present a hazard to other personnel on the deck
area or passage-ways of the boat. Use the provided cable-tie to coil and secure any surplus cable.
•Do not rely on the connection between the electronics box and the transducer cable, as a means of
securing the sonar to the boat. The sonar transducer head should be fixed directly to the boat hull.
6.3. Other Precautions
For storage and maintenance information, please refer to the section “Maintenance & Cleaning” (see page 19).
If you have any other safety or operational queries, please contact StarFish technical support (see page 21).

StarFish Hull-Mounted
System Manual
19
7. Care Of Your Starfish
7.1. Operational Care
In addition to the points highlighted in the “Safety” section (see page 18), please observe the additional
precautions…
•Do not operate the product near a source of heat that may cause the operational temperature
parameters to be exceeded (see specifications on page 24), or stack other heat generating equipment
on top of the unit.
•Always use the electronics module on a stable, non-slip, rigid, flat and lint-free surface.
•Make sure the product is more than 10cm away from any other appliance that may be susceptible to
electromagnetic interference.
7.2. Maintenance & Cleaning
When you have finished using your StarFish sonar, you should…
•Disconnect the product from the power supply before attempting any maintenance or cleaning.
•Remove any weed, or other detritus, from the sonar head and cable, that may have been collected
during its operation.
•Wipe, with a damp cloth, any salt-water spray that may have inadvertently settled on the surface of the
“top box” electronics module and connectors.
Additionally, please observe the following precautions for cleaning and maintenance…
•Do not clean with solvents, and only use a damp cloth on the exterior of the unit.
•Do not undertake maintenance of the unit, outside the scope of that defined within this manual, unless
instructed to do so by Technical Support.
•Do not insert extraneous object (metal or other alien substance) into the unit or any of its connector
apertures.
7.3. Storage
When storing or shipping the StarFish system, please observe the following…
•Avoid excessively bending or kinking the cable (below a radius of 30mm), as this could reduce its
operational life.
•Avoid excessive and large fluctuations in temperature.
•To prevent corrosion, remove any salt or other residues from the product before storage out of the
water.
•Store in a well-ventilated enclosure after use, to allow any moisture on system components to
evaporate naturally.
•Ensure no point-load is exerted on the transducers on either side of the sonar transducer head.

StarFish Hull-Mounted
System Manual
20
8. Troubleshooting
Below is a table of common problems and solutions, but if you have a problem that cannot be solved from the
table below, or an issue that is not covered, please contact Technical Support - see page 21 for further details.
Note: For software issues and problems, please refer to the accompanying “Scanline User Guide”.
Problem…
Solution(s)…
Electrical interference
This is most commonly seen as bright small snow-like dots over the image –
usually with some form of regular repeating pattern.
The most common cause is interference from other high-current switching
electrical devices (such as mains inverters, or motors) connected to the same
power source as the top box electronics module.
Try methodically turning off other electrical devices to find the cause, or
running the StarFish from its own dedicated supply (or battery).
Acoustic noise
This is most commonly seen as large stripes or pulses of varying brightness
over the image, usually with some form of regular repeating pattern.
Try to identify and, where possible, remove the source of the acoustic noise.
Most commonly, your boat, or other vessels, may have an echosounder that
is running at a frequency close to the operating frequency band of the
StarFish.
Image ghosting or mirroring
This problem may occur if the StarFish is operating in close proximity to the
boat hull. If depth permits, try deploying more cable to distance the sonar
transducer head from the boat.
This problem can also occur in shallow water, where the high-intensity
transmission from one transducer is being received by the other. If possible,
use the software to display only a single channel (and prevent transmissions
from the other); this will reduce the inter-channel cross-talk.