Technical data

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Furuno offers a selection of sensors for use with our TruEcho CHIRP fish finders. CHIRP sensors are capable of transmitting a precise
sweep pattern modulated within a range of frequencies, all within a single long-duration transmit pulse. Because the transmission lasts
for a longer amount of time, more energy is directed into the water column. The equivalent sound energy transmitted into the water
can be up to 1,000 times greater than a conventional fishfinder, resulting in more energy on target. The results are up to 5x greater
CHIRP Sensors
Transducer
Part number
Housing
Type
Mount
Type
Cable
Length
Low
Frequencies
High
Frequencies
Fairing Block Compatible Models
CHIRP Sensors
B265LH Bronze TH
10 M 42-65 kHz 130-210 kHz
Hi-Speed Fairing
Block Included
DFF1-UHD
CM265LH Urethane Tank NA DFF1-UHD
PM265LH
(Temp included)
Bronze Pocket/
Keel
NA DFF1-UHD
ACCU-FISH is a revolutionary fish size assess-
ment function. In order to assess individual fish
size, the echo strength from the fish needs to be
computed and turned into fish size display on
the screen. It can detect fish size of 4" to 80", in
depths of 6 to 300 feet.
Activating the ACCU-FISH from the menu, the
display will show fish size on the individual fish
echo. When the ACCU-FISH is used concur-
rently with fish marks, it greatly helps anglers
to identify fish targets on the display. You may
also select and display the target depth instead
of fish size, which helps to see how far the fish is
from the boat.
The fish mark can be utilized to display on in-
dividual fish echoes when detected. It helps be-
ginners to identify the fish targets on the display
for a more fun fishing experience. Fish mark is
selectable from two types of fish symbol, circle
and square. The fish symbol, displayed in two
different sizes (Large: over 10" , Small: 4" to 9"),
is a great help for anglers to identify fish targets.
Circle and square marks are used to identify
targets without hiding fish echo.
The Bottom Discrimination feature enables
the fish finder to indicate if the major compo-
nent of the bottom is rocks, gravel, sand or mud.
The Bottom Discrimination Function pro-
vides you with valuable information to locate
rich fishing grounds, while boosting your catch
of the day.
Keep the following in mind when using a
Bottom Discrimination Sounder:
1. Use at a depth of 10 - 300 feet
2. Use transducer in transom mount or
thru-hull mount
3. To show a consistent display, set the range
of the fish finder to “auto”
4. Enter your ship’s draft value
5. Use a ship speed of 10 knots or less
Probability Mode:
Standard Mode:
Mounting Options
Selecting the mounting location
Although it falls outside the scope of this guide to describe all of the details of installation, there are some
important points that are true for every transducer installation. Acoustic noise is always present, and
these sound waves can interfere with your transducers operation. Ambient (background) noise from
sources such as waves, fish and other vessels cannot be controlled. However, carefully selecting your
transducers mounting location can minimize the effect of vessel-generated noise from the propeller(s)
and shaft(s), other machinery, and other fish finders. The lower the noise level, the higher the gain set-
ting you'll be able to use effectively on your fish finder.
Always select a location where:
• Water flowing across the hull is smoothest with a minimum of turbulence and bubbles
• The transducer will be continuously immersed in water (not applicable for In-Hull models)
• There is a minimum of deadrise angle
• The transducer beam will not be obstructed by the keel or propeller shaft(s)
• There is adequate headroom inside the vessel for the height of the housing, tightening the nuts, and
removing the valve assembly and insert
As a rule, no transducer should be located near a water intake or discharge opening, directly aft of any
lifting strakes, steps or other obstructions or irregularities in the hull , or behind eroding paint (an indica-
tion of turbulence). The flow of water across the transducer face must be as smooth as possible in order
to get the best performance while cruising.
Fairing blocks
The purpose of a fairing block is threefold: to compensate for the
deadrise of the hull, to reduce drag, and to create a smooth surface for
water to flow cleanly and unaerated across the face of the transducer.
When a fairing block is correctly installed, boat drag will be minimized
and the flow of water over the transducer face will be free of bubbles
and turbulence.
A standard fairing is of a similar shape to its companion transducer.
By contrast, a high-speed fairing projects a longer, more streamlined
form. This elongated wedge shape cuts the water into two streams
which flow along its sides towards the tapered end, where they will
smoothly rejoin. The result of a well-installed fairing is excellent fish
finder performance above 15 knots.
After the fairing is cut, it must be shaped to the hull as precisely as pos-
sible with a rasp or power tool. A tight fit will allow water to flow more
smoothly over the transducer. If the transducer is recessed more than
0.5 mm (1/64th inch) inside the fairing, you should either shim the
transducer or carefully file or sand the fairing until the two are flush.
With
fairing block
Without
fairing block