Humminbird 425 SX User manual

OPERATIONS
MANUAL

THANK YOU FOR CHOOSING YOUR 425SX FISHFINDER, MADE BY
TECHSONIC INDUSTRIES, MANUFACTURER OF AMERICA’S #1 NAME IN
FISHFINDERS, HUMMINBIRD. HUMMINBIRD HAS BUILT ITS REPUTATION
BY DESIGNING AND MANUFACTURING TOP QUALITY, THOROUGHLY
RELIABLE MARINE EQUIPMENT. YOUR HUMMINBIRD PRODUCT IS
DESIGNED FOR TROUBLE-FREE USE IN EVEN THE HARSHEST MARINE
ENVIRONMENT.
IN THE UNLIKELY EVENT THAT YOUR HUMMINBIRD DOES REQUIRE
REPAIRS, WE OFFER AN EXCLUSIVE SERVICE GUARANTEE. COMPLETE
DETAILS ARE INCLUDED AT THE END OF THIS MANUAL.
WE ENCOURAGE YOU TO READ THIS OPERATIONS MANUAL CAREFULLY
IN ORDER TO GET FULL BENEFIT FROM ALL THE FEATURES AND USES OF
YOUR HUMMINBIRD PRODUCT.
WARNING! THIS DEVICE SHOULD NOT BE USED AS A
NAVIGATIONAL AID TO PREVENT COLLISION, GROUNDING,
BOAT DAMAGE, OR PERSONAL INJURY. WHEN THE BOAT IS
MOVING, WATER DEPTH MAY CHANGE TOO QUICKLY TO
ALLOW TIME FOR YOU TO REACT. ALWAYS OPERATE THE BOAT
AT VERY SLOW SPEEDS IF YOU SUSPECT SHALLOW WATER OR
SUBMERGED OBJECTS.
THANK YOU

Section 1: Installation preparation . . . . . . . . . . . . . . . . . . . 2
Parts Supplied . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Installation Overview . . . . . . . . . . . . . . . . . . . . . . . . . 2
Alternative Transducers and Mounting Methods. . . . . . 4
Beginning Installation . . . . . . . . . . . . . . . . . . . . . . . . . 5
Section 2: USING THE 425SX. . . . . . . . . . . . . . . . . . . . . . . 6
How Sonar Works . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Simulator Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 6
What You See On Screen . . . . . . . . . . . . . . . . . . . 7–12
Control Functions . . . . . . . . . . . . . . . . . . . . . . . . 12–15
Menu Functions . . . . . . . . . . . . . . . . . . . . . . . . . 15–25
Section 3: ADVANCED FEATURES. . . . . . . . . . . . . . . . . . . 25
Using Diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Section 5: MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . 27
Maintenance and Troubleshooting . . . . . . . . . . . . 27–30
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
TABLE OF CONTENTS

2
INSTALLATION PREPARATION
PARTS SUPPLIED
PARTS SUPPLIED
Before installing your 425SX, please ensure the following parts are included in
the box:
•425SX fishfinder
• Transducer with 6m (20') of cable and mounting hardware kit
• Mounting system and mounting hardware kit
• 2m (6' ) power cable
• Publications kit
Note: The 425SX+includes speed and temperature sensors with
appropriate hardware and instructions for installation.
If any of these items are missing contact your local dealer.
ACCESSORIES
Humminbird offers a wide assortment of accessories that complement and
expand the capability of your new 425SX. These accessories are designed with
the same high standards. The Humminbird Accessory catalog included with
your unit contains descriptions of the many accessories available and ordering
information. All Humminbird accessories are available through your full-service
Humminbird dealer.
INSTALLATION OVERVIEW
The 425SX consists of two primary components to install: the control head and
the transducer.
The control head contains the sonar transmit and receive circuitry, as well as the
user controls and display. It should be installed in a location that provides access
to the controls and visibility while in use. The control head mounts on a quick
disconnect mounting system that swivels and tilts, providing flexibility for
viewing from almost anywhere on the boat.

3
INSTALLATION PREPARATION
INSTALLATION OVERVIEW
The transducer converts electrical energy from the transmitter into mechanical
pulses or sound waves. The transducer also receives the reflected sound waves
and converts them back into electrical signals for display on the control head. It
should be installed in contact with the surface of the water in an area that has
smooth water flow - usually on the transom of the boat. There are several
mounting options for the transducer. Review
the following section to determine the
method that works for you and your boat.
Determining How to Mount the
Transducer
The 425SX includes a model XT-6-24
transducer. This transducer can be mounted
on the transom of the boat, or bonded to
the inside of a fiberglass hull boat.
The transom installation, which is the most
widely used, places the transducer on the
outside of the boat hull. This technique
produces the least signal loss, and provides a
way to adjust the transducer after
installation. The mounting hardware
included is designed to protect both
the boat and the transducer should the
boat strike debris in the water or when
trailering.
As an alternative to transom mounting,
it is possible on many fiberglass-hulled
boats to glue the transducer on the
inside of the boat hull. Since fiberglass
has similar sonar characteristics as
water, the sonar signal can pass
through the boat hull with minimal
loss. The hull of the boat must be single
layer construction (not double-hulled).
Also, any air trapped in the lamination
of the fiberglass would prevent the sonar
Transom Mounted Transducer
Inside the Hull Mounted Transducer

4
signal from passing through.
Inside the hull installations require no holes to be drilled into the boat and
through experimentation, high-speed operation comparable to transom
mounting can be achieved. Two part, slow cure epoxy is required to glue the
transducer in place.
ALTERNATE TRANSDUCERS AND MOUNTING METHODS
The 425SX comes with everything necessary for installation and operation on
most boats. However, there are several situations which may require a different
type of transducer. Inboard boats, wood or metal hulls, and sail boats create
unique transducer mounting needs. Alternate transducers and mounting
methods are detailed below.
Portable Mounting
The standard transducer can be adapted for
portable installations using part number MHX-PT2.
This accessory adapts your transducer to a suction
cup mount for temporary installation on the boat
hull or other surface.
Trolling Motor Mounting
The standard transducer can also be adapted to
mount on most trolling motors using part number
AD-STM-7. This accessory includes a bracket and
hose clamp that allows mounting the transducer to
the body of most trolling motors.
TRANSDUCER EXCHANGE
Other transducers are available as replacements for the standard transducer.
You may exchange your new and unassembled transducer for another type by
returning it to the address listed in Customer Support. Some transducers may
have additional costs. Refer to the Accessory catalog or call Customer Support
for information.
INSTALLATION PREPARATION
ALTERNATE TRANSDUCERS AND MOUNTING METHODS

BEGINNING INSTALLATION
Now that you have determined the transducer mounting method, you can
begin installation of the 425SX. The fold out installation guide included
provides detailed step by step instructions for installation of the control head
and transducer. For transom mount transducer installations, you will need the
mounting template at the back of this manual.
In addition to the parts included you need the following for installation and
operation:
• A powered hand drill and various drill bits
• Phillips and flat-head screw drivers
• A ruler or measuring tape
• Pen or pencil
• 12 volt power source (your boat’s battery)
• A 1-amp fuse
• A fuse holder (if you are wiring directly to the boat’s battery)
• Silicone sealant (for sealing drilled holes)
• 2-part, slow-cure epoxy (for inside the hull transducer installations)
INSTALLATION PREPARATION
BEGINNING INSTALLATION
5
Note: If you have purchased the 425SX+you will have in addition
to the parts and instructions above:
• Speed and Temperature sensors
• Instructions for installing speed and temperature sensors
• Appropriate hardware to mount sensors

USING THE 425SX
HOW SONAR WORKS
6
HOW SONAR WORKS
Your Humminbird unit uses sonar to
locate and define underwater objects,
define the bottom terrain, as well as
determine distance.
Sonar technology is based on sound
waves. Your Humminbird unit sends out
a sound wave signal. With this signal it
determines distance by measuring the
time between the transmission of the
sound wave and when the sound wave
is reflected off an object. Your
Humminbird uses the reflected signal to
interpret location, size and composition of an object.
Sonar is very fast. A sound wave can travel from the surface to a depth of 70m
(240') and back again in less than ¹⁄₄ of a second. It is unlikely that your boat
can "outrun" this sonar signal.
The 425SX is a 200 kHz, single-beam fishfinder. The 200 kHz frequency
provides excellent sonar resolution (the ability to distinguish small returns or
returns which are close to the bottom), while providing depth capabilities to
185m (600’). The shape of the sonar beam is symmetrical and covers an area
of approximately 24 degrees side to side and front to rear.
Actual depth capability depends on factors such as bottom hardness, water
conditions, and transducer installation. Units will typically read to deeper
depths in fresh water than in salt water.
SIMULATOR OPERATION
The 425SX contains a simulator that allows you to use the unit as if you are on the
water. The simulator is invaluable for learning how to operate the 425SX.
There are two ways to start the simulator. If the unit is powered off, press and hold
the POWER button for approximately three seconds until you hear a continuous chirp.

7
USING THE 425SX
SIMULATOR OPERATION
The simulator can also be started by selecting
the Simulator option on the start-up screen
after you power-up the unit. When this
screen is shown, simply press the DOWN
ARROW until “Simulator” is highlighted.
When the screen times out, the unit will be
in simulator mode.
When in simulator operation, the 425SX responds to control inputs as if it is in
actual operation, so feel free to experiment, or to customize the unit for your
particular operation.
To exit Simulator mode, power the unit off.
FEATURE MEMORY
If your 425SX is installed with a transducer connected, any changes you make
to the set-up or User Options (see Control Functions) while in Simulator are
retained in the unit’s memory. This allows you to use simulator to experiment
with the various set-up options, and retain your selected settings for normal
operation.
If you are using the 425SX in Simulator when no transducer is connected, any
selected options are lost when the unit is powered off. The 425SX will return
to Factory Settings, or options selected when last used with a transducer, if no
transducer is connected.
IMPORTANT: A transducer must be connected to the 425SX in
order to retain user settings selected when in simulator mode. If
no transducer is detected, the unit defaults to pre-selected
options when powered off.
What You See On-Screen
Your 425SX uses a 160 x 160 matrix FSTN LCD display. This display provides
outstanding viewability in all light conditions over a wide range of
temperatures.

At initial power-up, the 425SX uses settings that were set at the factory. After
initial use, the 425SX will remember the settings you enter.
There are several elements on-screen that are common to all modes of
operation.
Temperature/Speed. The
initial screen layout takes one
of two basic forms depending
on whether the optional
Temp/Speed accessory is
installed. Figure A shows the
default view when the
Temp/Speed accessory is
installed. Figure B shows the
default view when the
Temp/Speed accessory is not
installed.
Depth. The digital depth
number shows the water
depth directly beneath the
transducer location.
Depth Range. The depth range
is shown to the right of the screen.
The upper number is 0 indicating
the surface of the water. The lower
number is one of the nine depth
ranges available that best match
the depth of the water. As the
depth of the water changes, the
range changes as necessary in
order to retain a bottom
representation on-screen.
8
Bottom Depiction
USING THE 425SX
WHAT YOU SEE ON-SCREEN
Figure B
6
Zero Line
Figure A
Water Depth Depth Range

When in Auto mode, the horizontal line at the top of the screen is the “zero
line,” representing the surface of the water. Occasionally there is a gap in this
line. This gap indicates the unit is updating the display even if the bottom is not
visible on-screen, or if the bottom information is not changing.
New sonar information appears on the right side of the graphic area of the
display and moves to the left as new information is displayed. The 425SX
automatically selects the appropriate depth range to show the depth of water
beneath the transducer. This range is selected so the bottom representation is
typically shown about ²⁄₃ down the display.
Bottom. The graphic depiction of the bottom provides the user with an
effective tool for understanding the composition of the bottom. The FSTN type
display uses 4 discrete levels of gray to indicate the intensity of the returned
sonar signal. The 425SX can display even the smallest sonar returns with light
gray pixels. Larger returns are displayed with darker shades of gray. If the
bottom is hard and smooth, the bottom depiction is narrow and dense. If the
bottom is soft mud or sand, the depiction will be thick and less dense. This
indicates that much of the signal is absorbed by the soft bottom. If the bottom
is rocky or rugged in composition, the depiction is of varying density and
textured in appearance.
Wave action also affects the bottom
depiction. The information drawn is
a distance measurement, so if the
boat is moving up and down over
flat bottom, the bottom depiction
often appears in regular variations
that match wave timing.
Structure. Structure is defined as
any object physically attached to the
bottom. The sonar configuration of
the 425SX is optimized to give the
most accurate depiction of bottom
structure possible. Grass, trees,
stumps, wrecks or other debris are
accurately displayed, however the
9
USING THE 425SX
WHAT YOU SEE ON-SCREEN
Surface Clutter Rocky Bottom
Hard Bottom Soft Bottom
m

depiction of these objects varies with boat speed and direction. The best way to
learn to interpret structure is to operate the 425SX over a variety of known
conditions and experiment with user functions to best represent those
conditions on-screen.
Surface Clutter. Surface clutter is the layer of water near the surface that is rich
in algae and other growth, and often is aerated by wind or wave action. This
area of water interferes with sonar transmission and often appears on-screen as
regular clusters of individual dots near the “0” line.
Thermoclines. Thermoclines are sharp differences in water temperature. These
are easily identified by the continuous nature of the return.
Second Returns. When a
sonar signal is reflected off the
bottom back to the transducer,
there is often enough energy
left in the signal to be reflected
off the surface of the water
back to the bottom a second
time. Second returns appear as
a slightly weaker bottom
representation exactly twice the
depth of the primary bottom
return. The second return is
most likely to occur in shallow
water and in areas of relatively
hard bottom.
Fish Arches.
With Fish ID off, schools of bait fish as well as individual fish
are clearly visible on the 425SX display. Bait fish appear as "clouds" having
different shapes and sizes depending on the number of fish and boat
speed. Individual fish appear as smaller black and gray lines often
appearing as a "fish arch." A fish arch forms as the boat moves over the
fish. Due to the transducer beam angle the distance to the fish decreases
as it moves into the beam, and then increases as it moves out. When the
window graphs this distance change, an arch appears. The true depth of
the fish is the top of the arch when the boat is directly over the fish. Boat
10
USING THE 425SX
WHAT YOU SEE ON SCREEN
Thermocline Second Return

speed and movement of the fish greatly affect
the shape of the arch. When moving slowly, a
fish creates an elongated arch. With the boat
moving fast the arch appears shorter. A partial
arch forms when the fish does not move through
the entire cone angle.
The 425SX displays structure such as submerged grass, brush, trees and
wrecks on the bottom. Structure can be distinguished by comparing the
area just above and below the main bottom return. Usually structure shows
as areas of dark to light gray on top of a dark bottom contour. The
appearance of structure is greatly affected by boat speed and direction; to
repeat the same image it is often necessary to travel the same speed and
direction over the location where the structure was originally located.
The 425SX is also capable of showing layers of water having different
temperatures. These temperature differences, called thermoclines, appear at
different depths, depending on current conditions. A thermocline typically
appears as a continuous band of light gray moving across the display at the
same depth. Thermoclines always appear above the bottom.
It is important to remember that sonar cannot distinguish between a fish
and some other object suspended in the water. Regardless of the object the
sonar detects, each could be drawn as an arch.
Fish ID. The 425SX uses
advanced signal processing
to further evaluate any
sonar return between the
surface and the bottom. For
instance, a small school of
bait fish usually appears as a
dense cluster of individual
dots. If the return meets
certain additional criteria, a
fish symbol will be assigned.
There are three different size
fish symbols used to indicate
11
USING THE 425SX
WHAT YOU SEE ON SCREEN
ID+ Fish Depth
Fish Arch Diagram

the intensity of the sonar return. While signal intensity is a good indicator of
relative fish size, different species of fish have different sonar characteristics, so
it is not always possible to distinguish fish size between varying species. The
signal intensity is "normalized" for depth so that a small fish close to the boat
does not appear as a large fish symbol.
ID+ adds an additional piece of information to help the user locate fish. On selected
fish symbols, the digital depth of the designated fish is drawn to help locate the fish
vertically. This is especially helpful in setting bait depths or for downrigger
operation.
CONTROL FUNCTIONS
The 425SX uses a simple six button keypad for all user input. Press any button
and an audible “chirp” confirms the control input. If a button has no function or
is inappropriate for the situation, an audible “error” is heard. The unit sounds
multiple chirps.
Power. The Power button powers the 425SX up for normal operation. When the
unit is on, POWER turns the unit off. POWER can also be used to go directly into
Simulator mode. To enter simulator, with the unit powered off,
press and hold POWER for several seconds until a continuous chirp
is heard.
Light. LIGHT controls the unit’s display backlight. With the unit
powered on, press LIGHT once to turn the backlight on “low.”
Press LIGHT a second time to turn the backlight on “medium,” a
third time to turn the backlight on “high”, and a fourth time to
turn the backlight off. The backlight is very effective for low-light
and nighttime operation. When the backlight is on, the 425SX will
consume more power than with the backlight off. This is
important when using the 425SX in a portable configuration
powered by a separate battery, or when powering the unit from a
trolling motor battery.
12
USING THE 425SX
CONTROL FUNCTIONS

When powering the unit from a battery such as in portable
applications, you can prolong the battery life by using the
backlight at a minimum.
The three lower buttons, MENU, UP ARROW and DOWN ARROW work together
to control the 425SX menu-controlled user functions.
View. VIEW selects one of
several screen configurations or
“views” possible depending on
the transducer in use. When
using the standard transducer,
without the optional
speed/temp sensor connected,
the VIEW button toggles the
display between the full-screen
2D View and the Large Digital
Readout View.
The 2D View is the default view,
and the view which is first seen
at power-up. Pressing VIEW
again will select the Large
Digital Readout View, which
increases the size of key digital
information so that it can be
viewed from a great distance.
Normal 2D information is
displayed on the right side of
the display. Pressing VIEW again
will toggle the display back to
the 2D view.
When using the standard
transducer, with the optional speed/temp sensor connected, the VIEW button
toggles the display between the full-screen 2D View, the Chart View and the
Large Digital Readout View.
13
USING THE 425SX
CONTROL FUNCTIONS
6
2D View
Large Digit View

The Chart View, shows only the
digital depth readout, leaving
more screen area for fish
location and bottom depiction.
Menu. MENU displays a menu
on-screen for adjustment. In
normal operation, pressing
MENU repeatedly cycles
through all available menus. A
menu remains on-screen for
several seconds, and can be
adjusted by using the ARROW
keys. If no adjustment is made in the allotted
time, the menu disappears. If you want the menu
to remain on-screen longer press and hold
MENU—the menu will remain on-screen
indefinitely. Once you release the menu button,
the screen will time out. Once a menu times out,
it is still considered the active menu. Press MENU
to bring up the last menu used.
Arrow Keys. The UP ARROW and DOWN ARROW make adjustments to menu
functions. On the left side of every menu there are UP ARROW and DOWN
ARROW symbols. The symbols indicate which ARROW button has a function in
a particular situation. Either one or both ARROW buttons can be used to adjust
the menu function. A hollow ARROW symbol means the corresponding ARROW
button has no function. Pressing that button will result in no adjustment and the
“error” audible will be heard. A solid ARROW symbol means the corresponding
ARROW button can be used to affect the menu adjustment.
Abbreviated Menu. The ARROW buttons often can be
used when no menu is on-screen. In these situations,
pressing the ARROW button affects the function of the
active (last-used) menu. This is a short-cut to menu
operation. An abbreviated menu appears on-screen while
the adjustment is made and times out. A frequently used menu can be
adjusted very quickly using this technique.
14
USING THE 425SX
CONTROL FUNCTIONS
Abbreviated Menu
Chart View
Menu

After an adjustment is made to a menu function, the menu times out after a few
seconds and the unit returns to normal operation.
Menu Layout. All menus use the same basic layout. The heading at the top
describes the menu function. The UP ARROW and DOWN ARROW symbols to
the left of the menu indicate which buttons are available for adjustment. In
menus that have several possible settings, a range of adjustment indicator shows
the total range available and the current setting.
Within the menu are the options available. The selected option or current
setting is highlighted in the black box. If no adjustment is made, this is the
selected setting. Press an ARROW button while the menu is displayed to select
another option.
Several of the menus are multi-step. In some situations if an adjustment is
made, additional options become available for further adjustment. Examples of
these multi-step menus are Depth Range, Depth Alarm and Zoom. See the
detailed description of each function for further explanation.
Menu Functions
Sensitivity. The Sensitivity function controls the sensitivity of the sonar
receiver. The 425SX automatically adjusts the level of
receiver sensitivity based on a number of factors
including the depth of the water and the level of
noise present. Noise can be caused by other
electronic devices, engines, trolling motors, propeller
cavitation and hydrodynamic flow among others.
15
USING THE 425SX
MENU FUNCTIONS
Heading
Up Arrow Option
Down Arrow Option
Arrow Symbols
Selected Setting
Range of Adjustment Indicator

The user has the option of
adjusting the Sensitivity higher
or lower based on personal
preference. You can select one
of 11 sensitivity settings from -
5 to +5. A setting of 0 (factory
setting) has no effect on the
automatic sensitivity control.
Increasing the sensitivity (+1
through +5) enables the unit to
display the information from
progressively smaller sonar
returns. By decreasing the
sensitivity (-1 through -5), the
unit effectively filters small
sonar returns.
In murky or muddy water, it is often helpful to reduce the sensitivity. This
prevents the display from being cluttered with sonar returns from debris or
suspended particles. In very clear or very deep water, it may be helpful to increase
the sensitivity since even the smallest sonar return may be of interest to the user.
To adjust Sensitivity, press MENU repeatedly until the Sensitivity heading is
displayed. When the Sensitivity menu appears, use the UP ARROW to increase the
sensitivity, or the DOWN ARROW to reduce sensitivity. To sequence through the
available settings, press and hold either ARROW button. Release the button at the
setting you want to select.
After an adjustment is made, the menu disappears and the new sensitivity setting
is in affect. If additional time is needed to study a menu, press and hold the MENU
button and the menu will remain on-screen indefinitely. If you need to make an
additional adjustment, press the UP ARROW or DOWN ARROW button.
Depth Range. The Depth Range function controls the vertical distance displayed
on the graphic area of the display. There are nine depth ranges available. The top
of the range is always 0, or the surface of the water. Ranges of 0–5, 0–10, 0–20,
0–40, 0–60, 0–80, 0–110, 0–150, and 0–185 metres and imperial ranges of
0–15', 0–30', 0–60', 0–120', 0–180', 0–240', 0–360', 0–480', and 0–600'.
16
USING THE 425SX
MENU FUNCTIONS
High Sensitivity Sensitivity at “0”
Low Sensitivity

The range that positions the bottom depiction
closest to the bottom of the screen, will best utilize
the available display resolution.
Using the factory setting of AUTO the 425SX can
automatically adjust the depth range depending
on the depth of the water. The unit tries to
maintain the bottom depiction about ²⁄₃ down the
total range (for example, in 6 m (20') of water, the
0-10m (0-30') range would be selected). This
provides the best display resolution and therefore
the best target separation possible.
The Depth Range can be adjusted manually. Press
MENU repeatedly until the Depth Range menu is
visible. Two options are available: Auto and
Manual.
The manual setting enables you to adjust the
current depth range setting. The unit no longer
adjusts the Depth Range to the most appropriate
range for bottom display. Often, the bottom may
not be visible on-screen. The digital depth readout
always determines the depth of the bottom, even if it is not visible on-screen.
Using manual Depth Range
control, you can view sonar
information from the area near
the surface in greater detail.
To return to automatic Depth
Range control, press the
MENU button until the Depth
Range menu appears on-
screen and use the UP ARROW
to select AUTO.
17
USING THE 425SX
MENU FUNCTIONS
6
Depth Range

Zoom. The 425SX uses a greatly enhanced Zoom
capability called “TruZoom” which offers expanded
information on a select area of sonar information.
Zoom is similar to Depth Range because it controls the
range of information displayed on screen. Zoom,
however, allows for selection of ranges beneath the
surface so any area of water between the surface and
the bottom can be enlarged to provide more detailed information. By using the
full display to show a small area of coverage, the effective display resolution is
increased, and the unit’s ability to separate close targets is enhanced.
The Zoom ranges available are dependent on the
current depth range. In the 5m (15') depth range,
TruZoom displays a range equal to one half the
current depth range. In the 10m (30'), 20m (60'), 40m
(120'), 60m (180'), 80m (240'), 110m (360'), 150m
(480') and 185m (600') depth ranges, TruZoom
displays a range equal to one fourth the current depth
range. The box at the right side of the screen outlines
the area to be zoomed.
The 425SX shows Zoom range in conjunction with
the full depth range. The Zoom range is shown on
the left side of the screen and full range information
is shown on the right side of the display. The area
which is being enlarged by Zoom is indicated by the
square box. Zoom can either operate automatically,
in which the Zoom range is constantly adjusted to
show the bottom, or manually, in which the user
controls the location of the Zoom range.
“Automatic” Zoom is especially helpful when looking
for structure or bottom detail. The “Automatic” Zoom
keeps the bottom in view even in quickly changing
terrain. “Manual” Zoom provides detailed information
of any area from the surface to the bottom.
18
USING THE 425SX
MENU FUNCTIONS