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trademarks of LEI. Fishing Hot Spots
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Table of Contents
Section 1: Read Me First!........................................................ 1
Capabilities and Specifications: LCX-20C .................................... 3
How Your Sonar Works ................................................................ 5
How Your GPS Works .................................................................. 6
Introduction to GPS and WAAS................................................... 7
How to use this manual: typographical conventions ................ 10
Section 10: Supplemental Material ................................... 179
Notes.............................................. Error! Bookmark not defined.
v
A CAREFUL NAVIGATOR NEVER RELIES ON ONLY ONE METHOD
TO OBTAIN POSITION INFORMATION.
WARNING!
When showing navigation data to a position (waypoint), a GPS unit will show
the shortest, most direct path to the waypoint. It provides navigation data to the
waypoint regardless of obstructions. Therefore, the prudent navigator will not
only take advantage of all available navigation tools when traveling to a
waypoint, but will also visually check to make sure a clear, safe path to the
waypoint is always available.
When a GPS unit is used in a vehicle, the vehicle operator is solely
responsible for operating the vehicle in a safe manner. Vehicle
operators must maintain full surveillance of all pertinent driving,
boating or flying conditions at all times. An accident or collision
resulting in damage to property, personal injury or death could occur if
the operator of a GPS-equipped vehicle fails to pay full attention to
travel conditions and vehicle operation while the vehicle is in motion.
CAUTION
WARNING!
vi
Section 1:
Read Me First!
How this manual can get you out on the road, fast!
Welcome to the exciting world of digital sonar and GPS! We know
you're anxious to begin navigating and finding fish, but we have a favor
to ask. Before you grab the unit and begin installing it, please give us a
moment or two to explain how our manual can help you get the best
performance from your combination fish finder and GPS receiver.
First, we want to thank you for buying a Lowrance sonar/GPS unit.
Whether you're a first time user or a professional fisherman, you'll
discover that your unit is easy to use, yet capable of handling
demanding navigation and sonar tasks. When you team your unit with
our custom mapping software MapCreate 6, you have an incredible
combination. With a full VGA color display, recording capability and
remarkable resolution, you won't find another GPS/sonar unit with this
much power and this many features for this price!
Our goal for this book is to get you on the water. Like you, we'd rather
spend more time boating or fishing and less time reading the manual!
So, we designed our book so you don't have to read the whole thing from
front to back to find the information you want. At the start (or end) of
each segment, we'll tell you what content is coming up next. If it's a
concept you're already familiar with, we'll show you how and where to
skip ahead for the next important topic. We've also made it easy to look
up any tips you may need from time to time. Here's how:
The manual is organized into 10 sections. This first section is an
introduction to the LCX-20C sonar and GPS. It tells you the basics you
need to know so you’ll easily be able to make the unit, not only tell you
where you are, but also where to find fish.
Section 2 will help you install your unit, the transducer and the GPS
antenna module. We'll also show you how to install the MultiMedia
Card (MMC) and give you some information on available accessories.
Section 3 covers Basic Sonar Operation. It will show you how easy it is
to run your sonar, right out of the box. This section features a one-page
Sonar Quick Reference. (If you've already jumped ahead and
figured out how to install the unit yourself, and you just can't
wait any longer, turn to the Quick Reference on page 51 and
head for the water with your unit!)
After you've gained some experience with your sonar, you'll want to
check out Section 4, which discusses advanced Sonar Options andOther Features.
1
When you come to a sonar menu command on the unit's screen, you can
look it up in the manual by skimming over the table of contents, flipping
through Section 3, or scanning through the sonar options in Section 4.
If you're having difficulty with your sonar, you can find an answer to
the most common problems in Section 5, Sonar Troubleshooting.
The manual switches from sonar to navigation in Section 6, which
introduces you to Basic GPS Operations. This section features a one-
page GPS Quick Reference on page 107.
Section 6 contains short, easy-to-scan GPS lessons that follow one
another in chronological order. They're all you'll need to know to find
your way on the water quickly.
After you've learned the basics (or if you already have some GPS
experience), you may want to try out some of the unit's many advanced
navigation features. That brings us to Section 7, Advanced GPSOperations. This section contains the rest of the unit's GPS command
functions, organized in alphabetical order.
When you come to a GPS menu command on the screen, you can look it up
in the manual by skimming over the table of contents, flipping through
Section 6, or scanning through the command portion of Section 7.
This unit is ready to use right out of the box, but you can fine tune and
customize its operation with dozens of options. Since sonar is the unit's
key feature, we put the main sonar options in Section 4. Some options,
such as screen brightness settings, affect both sonar and GPS
operations. We describe how to use those common options along with
GPS options in Section 8, System Setup and GPS Setup Options.
Section 8 is organized in alphabetical order.
In Section 9, we go into more detail on one of the unit's most remarkable
GPS capabilities — Searching. We'll introduce a search example in the
Basic GPS Operation section, but there are so many map items you can
search for, we had to give this function its own section in the manual! For
example, did you know your unit can look up business phone numbers,
like a virtual Yellow Pages? We’ll show you how in Section 9.
Finally, in Section 10, we offer Supplemental Material, including a list
of the GPS datums, warranties and customer service information.
Now, if you're into the fine details, glance over the next segment on
specifications to see how much sonar and GPS power your unit contains.
It's important to us (and our power users), but, if you don't care how
many watts of power the unit has, or how many waypoints it can store,
skip ahead to important information on how sonar works, on page 5.
(Background on GPS begins on page 6.)
2
Capabilities and Specifications: LCX-20C
General
Display:............................ High-brightness LCD; programmable to
viewing preference.
LCX-20C: 6.0" (15.2 cm) diagonal.
Resolution:...................... LCX-20C: 320 pixel x 240 pixel resolution;
76,800 total pixels; 256-color, full VGA.
Backlighting:.................. Fluorescent cold cathode backlit screen with
multiple lighting levels; backlit keypad.
Input power:................... 10 to 15 volts DC.
Current drain: ............... Sonar only: 500 ma lights off; 600 ma lights
on. With GPS and lights on: 700 ma.
Case size:......................... 7.3" H x 9.6" W x 3.7" D (18.5 x 24.4 x 9.4
cm); sealed and waterproof; suitable for
saltwater use.
MMC slots: ...................... Two in waterproof compartment (SD card
compatible).
Back-up memory: .......... Built-in memory stores sonar records and
GPS data for decades. User settings are
stored when unit is turned off.
Languages:...................... 10 languages selectable by user.
Sonar
Frequency:...................... Depending on transducer, either 50/200 kHz
dual-frequency or 200 kHz single-frequency.
Transducers: .................... Skimmer
temperature sensor available. Use either a
dual-frequency transducer with 35°/12° cone
angles or a single-frequency transducer with a
20° cone angle. Both transducers operate at
speeds up to 70 mph (61 kts).
Contains: enhanced detail of continental U.S.
and Hawaii.
Custom mapping: .......... MapCreate
6 software optional; optional
plug and play LEI FreedomMaps offer the
same high-detail without the computer work
of MapCreate. Other plug and play mapping
options include IMS Fishing Hot Spots
LEI NauticPaths charts and Navionics
,
charts.
Mapping memory: ......... Up to 1 GB on one MMC (or SD) card.
Position updates: .......... Every second.
Position points: ............. 1,000 waypoints; 1,000 event marker icons.
Routes:............................. 100; up to 100 waypoints per route.
Plot Trails: ...................... 10 savable; up to 9,999 points per trail.
Zoom range:.................... 37 ranges; 0.05 to 4,000 miles.
NOTE:
The above memory capacities refer only to the unit's on-board
memory. The amount of GPS or sonar data you can record and save
for recall later is only limited by the number of MMC cards you have.
4
NOTICE!
The storage and operation temperature range for your unit is from 4 degrees to +167 degrees Fahrenheit (-20 degrees to +75 degrees
Celsius). Extended storage or operation in temperatures higher or
lower than specified will damage the liquid crystal display in your
unit. This type of damage is not covered by the warranty. For more
information, contact the factory's Customer Service Department.
Phone numbers are listed on the last page.
How Your Sonar Works
Sonar has been around since the 1940s, so if you already know how it
works, skip down to read about the relatively new technology of GPS.
But, if you've never owned a sonar fish finder, this segment will tell you
the underwater basics.
Sonar is an abbreviation for SOund NA
technology developed during World War II for tracking enemy
submarines. (Lowrance developed the world's first transistorized
sportfishing sonar in 1957.) A sonar consists of a transmitter,
transducer, receiver and display. Here’s a simple explanation of how it
finds the bottom and the fish.
The transmitter emits an electrical impulse, which the transducer
converts into a sound wave and sends into the water. (The sound
frequency can't be heard by humans or fish.) The sound wave strikes an
object (fish, structure, bottom) and bounces back to the transducer,
which converts the sound back into an electrical signal.
The receiver amplifies this return signal, or echo, and sends it to the
display, where an image of the object appears on the scrolling sonar
chart. The sonar's microprocessor calculates the time lapse between the
transmitted signal and echo return to determine the distance to the
object. The whole process repeats itself several times each second.
Your sonar unit can record a log of the sonar signals that scroll across
the screen and save them to the MMC memory card. (These recordings
are also called sonar charts or sonar graphs.) You can replay this sonar
log in the unit using the Sonar Simulator function, or play it back on a
personal computer using our free Sonar Viewer. The viewer is available
for download from the Lowrance web site, www.lowrance.com.
You can save several different sonar log files, erase 'em and record new
ones, over and over again. The size of your sonar recordings are only
limited by the free space available on your MMC.
vigation and Ranging, a
5
How Your GPS Works
You'll navigate faster and easier if you understand how this unit scans
the sky to tell you where you are on the earth — and, where you're
going. (But if you already have a working understanding of GPS
receivers and the GPS navigation system, skip on ahead to Section 2,
Installation & Accessories on page 11. If you're new to GPS, read on, and
you can later impress your friends with your new-found knowledge.)
First, think of your unit as a small but powerful computer. (But don't
worry — we made the series easy to use, so you don't need to be a
computer expert to find your way!) The unit includes a keypad and a
screen with menus so you can tell it what to do. The screen also lets the
unit show your location on a moving map, as well as point the way to
your destination.
This gimbal-mounted unit uses an external antenna/receiver module,
which makes the whole system work something like your car radio. But
instead of your favorite dance tunes, this receiver tunes in to a couple of
dozen GPS satellites circling the earth. (It will also listen in to the
WAAS satellites in orbit, but more about that in the upcoming segment
introducing you to GPS and WAAS.)
Your unit listens to signals from as many satellites as it can "see" above
the horizon, eliminates the weakest signals, then computes its location
in relation to those satellites. Once it figures its latitude and longitude,
the unit plots that position on the moving map shown on the screen.
The whole process takes place several times a second!
The performance doesn't stop there. Stored in the permanent memory
of every unit is a basic background map of the entire world. We lock it
in here at the factory — you can't change or erase this map.
The background map is suitable for many navigation chores, but for
maximum accuracy and much more detail, you need our optional mapmaking software, MapCreate 6. Some unit features — such as
searching for businesses and addresses — won't work without a custom
MapCreate map. There is so much detail in our background map (and
even more in MapCreate) that we'll describe its contents and
differences in Section 6, Basic GPS Operations, on page 95.
Another portion of the unit's onboard memory is devoted to recording
GPS navigation information, which includes waypoints, event marker
icons, trails and routes. This lets you look back the way you came. Think
of this data storage like the hard drive memory in a computer or a tape
in a cassette tape recorder. You can save several different GPS data files,
6
erase 'em and record new ones, over and over again. Like any computer
file, these GPS Data Files (file format *.usr) can be shared between
other Lowrance GPS or sonar/GPS units and even personal computers.
Your unit has one more thing in common with a personal computer.
Just as computers have a floppy disk drive for storing and exchanging
files, this unit has a slot for an MMC (MultiMedia Card) or SDC
(Secure Digital card) flash memory card. These solid-state memory
devices are about the size of a postage stamp, but can hold data ranging
from 8 MB to 1 GB in size. (Compare that to a floppy disk's 1.44 MB
capacity!) The unit uses all that MMC space for two key GPS purposes.
(The MMC is also used to record sonar logs. See page 5.)
First, you can backup your onboard GPS Data Files by copying them to
the MMC. Since the MMC is removable (like a floppy disk or a cassette
tape), you can store these GPS Data Files on a personal computer
equipped with an MMC card reader. (Or store them on a pocketful of
MMCs, if you don't have a computer.) Our MapCreate mapping software
can save, edit or create its own GPS Data Files, which can be copied to
the MMC and then loaded from the MMC into the unit's memory.
(NOTE: No matter where they come from, GPS Data Files must be
loaded from the MMC into memory before the unit can use them.)
The other key GPS use for MMCs is storage of special high-detail,
custom maps, which you can produce on your computer with our
MapCreate software. These MapCreate custom maps contain much
greater detail than the basic background map. These Custom MapFiles (file format *.lcm) can also be shared between other Lowrance
GPS or sonar/GPS units and personal computers. (For example, the
exact same MMC, custom map files and GPS data files can be used
interchangeably between your gimbal-mounted LCX-20C and the handheld iFINDER GPS receiver.)
The unit automatically reads Custom Map Files directly from the MMC
or SDC. To use a custom map, all you need to do is slide an MMC
containing a map into the unit.
Introduction to GPS and WAAS
Well, now you know the basics of how the unit does its work. You might
be ready to jump ahead to Section 2, Installation & Accessories, on page
11, so you can mount your unit and plug in the power. Or you might
want to see how our text formatting makes the manual tutorials easy to
skim. If that's the case, move on to "How to Use This Manual" on page
10. But, if you want to understand the current state of satellite
navigation, look over this segment describing how GPS and its new
companion WAAS work together to get you where you're going.
7
The Global Positioning System (GPS) was launched July 17, 1995 by
the United States Department of Defense. It was designed as a 24hour-a-day, 365-days-a-year, all weather global navigation system for
the armed forces of the U.S. and its allies. Civilian use was also
available, but it was less accurate because the military scrambled the
signal somewhat, using a process called Selective Availability (SA.)
GPS proved so useful for civilian navigation that the federal
government discontinued SA on May 2, 2000, after the military
developed other methods to deny GPS service to enemy forces. Reliable
accuracy for civilian users jumped from 100 meters (330 feet) under SA
to the present level of 10 to 20 meters (about 30 to 60 feet.)
Twenty-four satellites orbit 10,900 nautical miles above the Earth,
passing overhead twice daily. A series of ground stations (with precisely
surveyed locations) controls the satellites and monitors their exact
locations in the sky. Each satellite broadcasts a low-power signal that
identifies the satellite and its position above the earth. Three of these
satellites are spares, unused until needed. The rest virtually guarantee
at least four satellites are in view nearly anywhere on Earth at all times.
A minimum of three satellites are required to determine a 2D fix.
The system requires signal reception from three satellites in order to
determine a position. This is called a 2D fix. It takes four satellites to
determine both position and elevation (your height above sea level —
also called altitude). This is called a 3D fix.
Remember, the unit must have a clear view of the satellites in order to
receive their signals. Unlike radio or television signals, GPS works at
very high frequencies. These signals can be easily blocked by trees,
buildings, an automobile roof, even your body.
8
Like most GPS receivers, this unit doesn’t have a compass or any other
navigation aid built inside. It relies solely on the signals from the
satellites to calculate a position. Speed, direction of travel, and distance
are all calculated from position information. Therefore, in order for the
unit to determine direction of travel, you must be moving and the
faster, the better. This is not to say that it won’t work at walking or
trolling speeds — it will. There will simply be more "wandering" of the
data shown on the display.
GPS is plenty accurate for route navigation, but the U.S. Federal
Aviation Administration has special needs for aircraft traffic control
that go beyond basic GPS. The FAA has a plan under way to boost GPS
performance even further with its Wide Area Augmentation System, or
WAAS. This GPS add-on will include a time control element that will
help airliners fly closer together while avoiding collisions. In addition to
carefully spacing airplanes along travel corridors, WAAS will
eventually make instrument landings and takeoffs more accurate as it
replaces existing aviation navigation systems.
Non-aviators can use WAAS signals to make their GPS navigation even
more accurate. Your unit receives both GPS and WAAS signals. WAAS,
however, has some limits you should know about.
First, the U.S. government has not completed construction of the WAAS
system, so it is not yet fully operational. The ground stations are in place,
but only a few of the needed WAAS satellites have been launched.
WAAS can boost the accuracy of land GPS navigation, but the system is
designed for aircraft. The satellites are in a fixed orbit around the
Equator, so they appear very low in the sky to someone on the ground
in North America. Aircraft and vessels on open water can get
consistently good WAAS reception, but terrain, foliage or even large
man-made structures frequently block the WAAS signal from ground
receivers.
You'll find that using your GPS receiver is both easy and amazingly
accurate. It’s easily the most accurate method of electronic navigation
available to the general public today. But remember this receiver is
only a tool. Always have another method of navigation available, such
as a map or chart and a compass.
Also remember this unit will always show navigation information in
the shortest line from your present position to a waypoint, regardless of
terrain! It only calculates position, it can’t know what’s between you
and your destination. It’s up to you to safely navigate around obstacles,
no matter how you’re using this product.
9
How to use this manual: typographical conventions
Many instructions are listed as numbered steps. The keypad and arrow
"keystrokes" appear as boldface type, so you can easily skim the
instructions and pick out what menu command to use.
Arrow Keys
The arrow keys control the movement of dotted cross-hair lines on your
mapping screen called the cursor. The arrow keys also control a
horizontal line depth cursor on the sonar screen. The arrow keys also
help you move around the menus so you can execute different
commands. They are represented by symbols like these, which denote
the down arrow, up arrow, left arrow and right arrow: ↓ ↑ ← →.
Keyboard
The other keys perform a variety of functions. When the text refers to a
key to press, the key is shown in bold. For example, the "Enter/Icons"
key is shown as
Menu Commands
A menu command or a menu option will appear in small capital letters, in
a bold sans serif type like this:
to select this command or option from a menu or take an action of some
kind with the menu item. Text that you may need to enter or file names
you need to select are show in italic type, such as trail name.
Instructions = Menu Sequences
Most functions you perform with this unit are described as a sequence
of key strokes and selecting menu commands. We've written them in a
condensed manner for quick and easy reading.
For example, instructions for navigating a trail would look like this:
1. From the Map Page, press
2. Press ↓ to
3. You are asked to wait while it converts the trail into a route.
4. The wait message disappears and the unit begins showing
navigation information along the trail. Now, begin moving and
follow your unit's directions.
In clearer terms, step 1 (above) means: "Start on the Map Page. Press the
Menu key twice. Next, repeatedly press (or press and hold) the down
arrow key to scroll down the menu and select (highlight) the My Trails
menu command. Finally, press the Enter key."
Step 2: "Press the down arrow key repeatedly to scroll to the trail
named Trail 1, and press Enter. Next, press the right arrow key and
then the down arrow key to highlight the Navigate command, then
press Enter."
ENT and the "Menu" key is shown as MENU.
ROUTE PLANNING. These indicate that you are
MENU|MENU|↓ to MY TRAILS|ENT.
Trail 1|ENT|→|↓ to NAVIGATE|ENT.
10
Section 2:
Installation & Accessories
Preparations
You can install the sonar and GPS systems in some other order if you
prefer, but we recommend this installation sequence:
CAUTION:
You should read over this entire installation section before
drilling any holes in your vehicle or vessel!
1. Determine the approximate location for the sonar/GPS unit, so you
can plan how and where to route the cables for the antenna, transducer
and power. This will help you make sure you have enough cable length
for the desired configuration.
2. Determine the approximate location for the transducer and its cable
route.
3. Determine the approximate location for the GPS antenna module
and its cable route.
4. Determine the location of your battery or other power connection,
along with the power cable route.
5. Install the transducer and route the transducer cable to the
sonar/GPS unit.
6. Install the GPS antenna and route the antenna cable to the
sonar/GPS unit.
7. Install the power cable and route it to the sonar/GPS unit.
8. Mount the sonar/GPS unit.
Transducer Installation
These instructions will help you install your Skimmer
transom, on a trolling motor or inside a hull. These instructions cover
both single- and dual-frequency Skimmer transducers. Please read all
instructions before proceeding with any installation.
The smaller single-frequency Skimmers typically use a one-piece,
stainless steel mounting bracket. The larger dual-frequency Skimmers
typically use a two-piece, plastic mounting bracket. The trolling motor
mount uses a one-piece plastic bracket with an adjustable strap.
These are all "kick-up" mounting brackets. They help prevent damage if
the transducer strikes an object while the boat is moving. If the
transducer does "kick-up," the bracket can easily be pushed back into
place without tools.
11
transducer on a
Read these instructions carefully before attempting the installation.
Determine which of the mounting positions is right for your boat. Use
extreme care if mounting the transducer inside the hull, because once
the epoxy is applied and it is set into position, the transducer cannot be
removed. Remember, the transducer installation is the most
critical part of a sonar installation.
Recommended Tools and supplies
If you prefer the option of routing the cable through the transom, you
will need a 1" drill bit. A transom mount requires use of a high quality,marine grade above- or below-waterline caulking compound.
NOTE
The following installation types also call for these recommended
tools and required supplies (supplies are not included):
Single-frequency transom installations
Tools include: two adjustable wrenches, drill, #29 (0.136") drill bit, flathead screwdriver. Supplies: high quality, marine grade above- or belowwaterline sealant/adhesive compound.
Dual-frequency transom installations
Tools: two adjustable wrenches, drill, #20 (0.161") drill bit, flat-head
screwdriver. Supplies: four, 1" long, #12 stainless steel slotted wood
screws, high quality, marine grade above- or below-waterline
sealant/adhesive compound.
Single-frequency trolling motor installations
Tools: two adjustable wrenches, flat-head screwdriver. Supplies: plastic
cable ties.
Shoot-through hull installations
Tools: these will vary depending on your hull's composition. Consult your
boat dealer or manufacturer. Other tools are a wooden craft stick or
similar tool for stirring and applying epoxy, and a paper plate or piece
of cardboard to mix the epoxy on. Supplies: rubbing alcohol, 100 grit
sandpaper, specially formulated epoxy adhesive available from LEI (see
ordering information on the inside back cover). A sandwich hull also
requires polyester resin.
Selecting a Transducer Location
1. The location must be in the water at all times, at all operating speeds.
2. The transducer must be placed in a location that has a smooth flow of
water at all times. If the transducer is not placed in a smooth flow of
water, interference caused by bubbles and turbulence will show on
the sonar's display in the form of random lines or dots whenever the
boat is moving.
12
NOTE:
location
Deadrise less than 10
Some aluminum boats with strakes or ribs on the outside of the
hull create large amounts of turbulence at high speed. These boats
typically have large outboard motors capable of propelling the boat
at speeds faster than 35 mph. Typically, a good transom location on
aluminum boats is between the ribs closest to the engine.
3. The transducer should be installed with its face pointing straight
down, if possible. For shoot-thru applications: Many popular fishing
boat hulls have a flat keel pad that offers a good mounting surface. On
vee hulls, try to place the transducer where the deadrise is 10° or less.
°
Left, vee pad hull; right, vee hull. A pod style transducer is shown here,
Pad
but the principle is the same for Skimmers inside a hull.
Strakes
4. If the transducer is mounted on the transom, make sure it doesn't
interfere with the trailer or hauling of the boat. Also, don't mount it
closer than approximately one foot from the engine's lower unit. This
will prevent cavitation (bubble) interference with propeller operation.
5. If possible, route the transducer cable away from other wiring on the
boat. Electrical noise from engine wiring, bilge pumps and aerators
can be displayed on the sonar's screen. Use caution when routing the
transducer cable around these wires.
CAUTION: Clamp the
transducer cable to transom
near the transducer. This will
help prevent the transducer
from entering the boat if it is
knocked off at high speed.
Good
Poor angle
Good location
Poor location
Good location
Good and poor transducer locations.
13
How low should you go?
Transom
centerline
For most situations, you should install your Skimmer transducer so
that its centerline is level with the bottom of the boat hull. This will
usually give you the best combination of smooth water flow and
protection from bangs and bumps.
Transducer
Hull bottom
Align transducer centerline with hull bottom.
However, there are times when you may need to adjust the transducer
slightly higher or lower. (The slots in the mounting brackets allow you
to loosen the screws and slide the transducer up or down.) If you
frequently lose bottom signal lock while running at high speed, the
transducer may be coming out of the water as you cross waves or
wakes. Move the transducer a little lower to help prevent this.
If you cruise or fish around lots of structure and cover, your transducer
may be frequently kicking up from object strikes. If you wish, you may
move the transducer a little higher for more protection.
There are two extremes you should avoid. Never let the edge of the
mounting bracket extend below the bottom of the hull. Never let the
bottom – the face – of the transducer rise above the bottom of the hull.
Shoot-thru-hull vs. Transom Mounting
In a shoot-thru-hull installation, the transducer is bonded to the inside
of the hull with epoxy. The sonar "ping" signal actually passes through
the hull and into the water. This differs from a bolt-thru-hull
installation (often called simply "thru-hull"). In that case, a hole is cut in
the hull and a specially designed transducer is mounted through the
hull with a threaded shaft and nut. This puts the transducer in direct
contact with the water.
Typically, shoot-thru-hull installations give excellent high speed
operation and good to excellent depth capability. There is no possibility
of transducer damage from floating objects, as there is with a transommounted transducer. A transducer mounted inside the hull can't be
knocked off when docking or loading on a trailer.
14
However, the shoot-thru-hull installation does have its drawbacks.
First, some loss of sensitivity does occur, even on the best hulls. This
varies from hull to hull, even from different installations on the same
hull. This is caused by differences in hull lay-up and construction.
Second, the transducer angle cannot be adjusted for the best fish arches
on your sonar display. (This is not an issue for flasher-style sonars.)
Lack of angle adjustment can be particularly troublesome on hulls that
sit with the bow high when at rest or at slow trolling speeds.
Third, a transducer CAN NOT shoot through wood and metal hulls.
Those hulls require either a transom mount or a thru-hull installation.
Fourth, if your Skimmer transducer has a built in temp sensor, it will
only show the temperature of the bilge, not the water surface temp.
Follow the testing procedures listed in the shoot-thru-hull installation
section at the end of this lesson to determine if you can satisfactorily
shoot through the hull.
Transom Transducer Assembly And Mounting
The best way to install these transducers is to loosely assemble all of the
parts first, place the transducer's bracket against the transom and see if
you can move the transducer so that it's parallel with the ground.
The following instructions sometimes vary depending on the mounting
bracket that came with your transducer. Single-frequency Skimmers
come with a one-piece stainless steel bracket, while dual-frequency
Skimmers come with a two-piece plastic mounting bracket. Use the set of
instructions that fits your model.
1. Assembling the bracket.
A. One-piece bracket: Press the two small plastic ratchets into the
sides of the metal bracket as shown in the following illustration. Notice
there are letters molded into each ratchet. Place each ratchet into the
bracket with the letter "A" aligned with the dot stamped into the metal
bracket. This position sets the transducer's coarse angle adjustment for a
14° transom. Most outboard and stern-drive transoms have a 14° angle.
15
Dot
Align plastic ratchets in bracket.
B.Two-piece bracket: Locate the four plastic ratchets in the
transducer's hardware package. Press two ratchets into the sides of the
plastic bracket and two on either side of the transducer as shown in the
following illustrations. Notice there are letters molded into each ratchet.
Place the ratchets into the bracket with the letter "A" aligned with the
alignment mark molded into the bracket. Place the ratchets onto the
transducer with the letter "A" aligned with the 12 o'clock position on
the transducer stem. These positions set the transducer's coarse angle
adjustment for a 14° transom. Most outboard and stern-drive transoms
have a 14° angle.
Alignment letters
Alignment
positions
Transducer
Transducer bracket
Insert and align ratchets.
16
Trans
ducer
bracket
Transducer
Ratchet
Add ratchets to bracket and transducer.
Ratchet
2. Aligning the transducer on the transom.
A. One-piece bracket: Slide the transducer between the two
ratchets. Temporarily slide the bolt though the transducer assembly
and hold it against the transom. Looking at the transducer from the
side, check to see if it will adjust so that its face is parallel to the
ground. If it does, then the "A" position is correct for your hull.
If the transducer's face isn't parallel with the ground, remove the
transducer and ratchets from the bracket. Place the ratchets into the
holes in the bracket with the letter "B" aligned with the dot stamped
in the bracket.
Reassemble the transducer and bracket and place them against the
transom. Again, check to see if you can move the transducer so it's
parallel with the ground. If you can, then go to step 3A. If it doesn't,
repeat step 2A, but use a different alignment letter until you can
place the transducer on the transom correctly.
Ratchets
Insert bolt and check transducer position on transom.
17
B. Two-piece bracket: Assemble the transducer and bracket as shown
Flat washer
in the following figure. Temporarily slide the bolt though the transducer
assembly but don't tighten the nut at this time. Hold the assembled
transducer and bracket against the transom. Looking at the transducer
from the side, check to see if it will adjust so that its face is parallel to
the ground. If it does, then the "A" positions are correct for your hull.
If the transducer's face isn't parallel with the ground, remove and
disassemble the transducer and ratchets. Place the ratchets into the
bracket holes with the letter "B" aligned with the bracket alignment
mark. Place them on the transducer aligned with the 12 o'clock
position on the transducer stem.
Reassemble the transducer and bracket and place them against the
transom. Again, check to see if you can move the transducer so it's
parallel with the ground. If you can, then go to step 3B. If it doesn't,
repeat step 2B, but use a different alignment letter until you can
place the transducer on the transom correctly.
Bolt
Flat washer
Assemble transducer and bracket.
Lock washer
Nut
3. Assembling the transducer.
A. One-piece bracket: Once you determine the correct position for
the ratchets, assemble the transducer as shown in the following
figure. Don't tighten the lock nut at this time.
Metal
Nut
Rubber
washers
Assemble transducer and bracket.
washer
Metal washer
Bolt
18
B. Two-piece bracket: Once you determine the correct position for
the ratchets, assemble the transducer as shown in the figure in step
2B. Don't tighten the lock nut at this time.
4. Drilling mounting holes.
Hold the transducer and bracket assembly against the transom. The
transducer should be roughly parallel to the ground. The
transducer's centerline should be in line with the bottom of the hull.
Don't let the bracket extend below the hull!
Mark the center of each slot for the mounting screw pilot holes. You
will drill one hole in the center of each slot.
Drill the holes. For the one-piece bracket, use the #29 bit (for the #10
screws). For the two-piece bracket, use the #20 bit (for the #12
screws).
Transom
Transom
Position transducer mount on transom and mark mounting holes.
Side view shown (left) and seen from above (right).
5. Attaching transducer to transom.
A. One-piece bracket: Remove the transducer from the bracket and
re-assemble it with the cable passing through the bracket over the
bolt as shown in the following figures.
For single-frequency Skimmer, route cable over bolt and through
bracket. Side view shown (left) and seen from above (right).
19
Both bracket types: Attach the transducer to the transom. Slide the
Flat-bottom hull
transducer up or down until it's aligned properly with the bottom of
the hull as shown in the preceding and following figures. Tighten the
bracket's mounting screws, sealing them with the caulking compound.
Adjust the transducer so that it's parallel to the ground and tighten
the nut until it touches the outer washer, then add 1/4 turn. Don'tover tighten the lock nut! If you do, the transducer won't "kick-up" if
it strikes an object in the water.
Bottom
of
hull
Deep-"vee" hull
Align transducer centerline with hull bottom and attach transducer to
transom. Rear view of dual-frequency Skimmer shown.
6. Route the transducer cable through or over the transom to the sonar
unit. Make sure to leave some slack in the cable at the transducer. If
possible, route the transducer cable away from other wiring on the
boat. Electrical noise from the engine's wiring, bilge pumps, VHF radio
wires and cables, and aerators can be picked up by the sonar. Use
caution when routing the transducer cable around these wires.
WARNING:
Clamp the transducer cable to the transom close to the
transducer. This can prevent the transducer from
entering the boat if it is knocked off at high speed.
If you need to drill a hole in the transom to pass the connector through,
the required hole size be 1".
CAUTION:
If you drill a hole in the transom for the cable, make sure it is
located above the waterline. After installation, be sure to seal the
hole with the same marine grade above- or below-waterline
sealant used for the mounting screws.
20
7. Make a test run to determine the results. If the bottom is lost at
Flat washer
high speed, or if noise appears on the display, try sliding the
transducer bracket down. This puts the transducer deeper into the
water, hopefully, below the turbulence causing the noise. Be careful
not to install the transducer bracket below the bottom of the hull!
TROLLING MOTOR BRACKET INSTALLATION
(single-frequency only)
1. Attach the optional TMB-S bracket to the transducer as shown in the
following figure, using the hardware supplied with the transducer.
(Note: The internal tooth washer is supplied with the TMB-S.)
TMB-S bracket
Bolt
Internal tooth washer
Nut
Attach motor mounting bracket to transducer.
2. Slide the adjustable strap supplied with the TMB-S through the slot
in the transducer bracket and wrap it around the trolling motor.
Position the transducer to aim straight down when the motor is in
the water. Tighten the strap securely.
3. Route the transducer cable alongside the trolling motor shaft. Use
plastic ties (not included) to attach the transducer cable to the
trolling motor shaft. Make sure there is enough slack in the cable for
the motor to turn freely. Route the cable to the sonar unit and the
transducer is ready for use.
Transducer mounted on trolling motor, side view.
21
TRANSDUCER ORIENTATION AND FISH ARCHES
If you do not get good fish arches on your display, it could be because
the transducer is not parallel with the ground when the boat is at rest
in the water or at slow trolling speeds.
Partial fish arches
Transducer aimed
too far back
Transducer aimed
too far forward
Full fish arch
Proper transducer angle
Transducer angles and their effects on fish arches.
If the arch slopes up – but not back down – then the front of the
transducer is too high and needs to be lowered. If only the back half of
the arch is printed, then the nose of the transducer is angled too far
down and needs to be raised.
NOTE:
Periodically wash the transducer's face with soap and water to
remove any oil film. Oil and dirt on the face will reduce the
sensitivity or may even prevent operation.
SHOOT-THRU-HULL PREPARATION
Hulls With Floatation Materials
The transducer installation inside a fiberglass hull must be in an area
that does not have air bubbles in the resin or separated fiberglass
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