Garmin 340c Owner's manual

Owner’s Manual

full-featured color sonar

Fishﬁnder 340C

Garmin International, Inc.

1200 East 151

Street,

Olathe, Kansas 66062, USA

Tel. (913) 397.8200 or (800) 800.1020

Fax (913) 397.8282

Garmin (Europe) Ltd.

Liberty House

Hounsdown Business Park,

Southampton, Hampshire, SO40 9RB UK

Tel. +44 (0) 870.8501241 (outside the UK)

0808 2380000 (within the UK)

Fax +44 (0) 870.8501251

Garmin Corporation

No. 68, Jangshu 2

Road,

Shijr, Taipei County, Taiwan

Tel. 886/2.2642.9199

Fax 886/2.2642.9099

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permission to download a single copy of this manual onto a hard drive or other electronic storage medium to be viewed and to print one

copy of this manual or of any revision hereto, provided that such electronic or printed copy of this manual must contain the complete text

of this copyright notice and provided further that any unauthorized commercial distribution of this manual or any revision hereto is strictly

prohibited.

Information in this document is subject to change without notice. Garmin reserves the right to change or improve its products and to make changes in the content

without obligation to notify any person or organization of such changes or improvements. Visit the Garmin Web site (www.garmin.com) for current updates and

supplemental information concerning the use and operation of this and other Garmin products.

Garmin

is a trademark of Garmin Ltd. or its subsidiaries, registered in the USA and other countries. CANet

™

, DynaColor

™

, and Ultrascroll

™

, AutoLocate

TracBack

, BlueChart

, and MapSource

are trademarks of Garmin Ltd. or its subsidiaries. These trademarks may not be used without the express permission of

Garmin.

March 2007 Part Number 190-00658-00 Rev. D Printed in Taiwan

Fishnder 340C Owner’s Manual i

IntroductIon > About thIs MAnuAl

IntroductIon

Thank you for choosing the Garmin

Fishnder 340C. The

Fishnder 340C is a full-featured, color sonar that offers a choice

of display styles, a dual beam or dual frequency option, and many

more features, including the following:

• Ultrascroll

™

, which gives you a much faster update rate on

your Sonar Pages.

• Auto Gain, which allows you to see more sh and structures.

•

CANet

™

capability, which allows you to connect your unit

to CANet-capable Garmin chartplotters, so you can read the

Sonar Pages on chartplotters located elsewhere in the boat.

• Round asher, which gives you an option for how to view

the sonar.

• Whiteline, which helps you to interpret bottom hardness.

• 2x and 4x automatic and manual zoom.

• Adjustable keel offset.

• Alarms for sh size, shallow water, deep water, and low

battery.

• NMEA sonar data output and navigation data input.

About This Manual

To get the most out of your Fishnder 340C, read this manual and

learn the operating procedures. This manual includes the following:

• Introduction—contains the Table of Contents, product

registration, contact, and cleaning information.

• Getting Started

—provides general information that can

help you before you install and use your Fishnder 340C.

•

—covers the installation and

testing for the Fishnder 340C.

 

—provides details about the

features and operations of the Fishnder 340C.

• Appendix—contains information, such as specications,

optional accessories, and messages that might appear. You

can also nd warranty information in the Appendix.

• Index—helps you quickly nd information in this manual.

This manual uses the term Warning to indicate a potentially

hazardous situation, which, if not avoided, could result in death or

serious injury.

This manual uses the term  to indicate a potentially

hazardous situation, which, if not avoided, may result in minor

injury or property damage. It may also be used without the symbol

to alert you to avoid unsafe practices.

ii Fishnder 340C Owner’s Manual

IntroductIon > tAble of contents

table of contents

Introduction ...........................................................................i

About This Manual ................................................................... i

Product Registration .............................................................. iii

Contact Garmin ...................................................................... iii

Caring for the Fishnder ....................................................... iii

Warning ................................................................................... iv

Getting Started .....................................................................1

Packing List ............................................................................. 1

Optional Accessories .............................................................. 1

Understanding the Fishnder and Sonar .............................. 2

Installing the Fishnder 340C ............................................5

Selecting a Location for the Fishnder ................................. 5

Mounting the Fishnder ......................................................... 6

Mounting the Transducer ....................................................... 9

Installing the Wiring Harness ............................................... 15

Testing the Installation.......................................................... 20

Using the Fishnder 340C ................................................21

Learning the Basic Functions .............................................. 21

Using the Fishnder 340C Keypad ...................................... 22

Understanding the Main Pages ............................................ 23

Using the Main Menu ............................................................ 26

Using the Adjustment Menu ................................................. 34

Conguring Advanced Data Fields ...................................... 37

Pausing a Sonar or Flasher Page ........................................ 39

Marking a Waypoint ............................................................... 40

Appendix ............................................................................42

Specications ........................................................................ 42

Optional Accessories ............................................................ 42

Messages and Alarms ........................................................... 43

Limited Warranty ................................................................... 44

Software License Agreement ............................................... 45

Index ...................................................................................46

Fishnder 340C Owner’s Manual iii

IntroductIon > Product regIstrAtIon, contAct gArMIn, And cArIng for the fIshfInder

Product Registration

Help us better support you by completing our online registration

today! Have the serial number of your Fishnder handy, and

connect to our Web site (http://www.garmin.com). Look for the

Product Registration link on our Home page.

Use this area to record the serial number (8-digit number located

on the back of the box). Be sure to keep your original sales receipt

in a safe place, or attach a photocopy inside the manual.

Serial Number: ___ ___ ___ ___ ___ ___ ___ ___

Contact Garmin

If you encounter any difculty while using your Fishnder, or if

you have any questions, in the U.S.A. contact Garmin Product

Support by phone: 913/397.8200 or 800/800.1020, Monday–

Friday, 8 AM–5 PM Central Time; or go to

www.garmin.com/support/ and click on Product Support. In

Europe, contact Garmin (Europe) Ltd. at 44/0870.8501241.

Caring for the Fishnder

The Fishnder case is constructed of high-quality materials and

does not require user maintenance except cleaning.

Cleaning the Case

Clean the Fishnder’s outer casing (except for the screen) using

a cloth dampened with a mild detergent solution. Wipe it dry.

Avoid chemical cleaners and solvents that can damage plastic

components.

Cleaning the Screen

Apply eyeglass lens cleaner to a clean, lint-free cloth, and then

gently wipe the screen with the moistened cloth.

The Fishnder 340C lens is coated with a special

anti-reective coating which is very sensitive to skin oils,

waxes, and abrasive cleaners. CLEANERS CONTAINING

AMMONIA HARM THE ANTI-REFLECTIVE COATING.

Storage

Do not store the Fishnder where prolonged exposure to

temperature extremes might occur (such as in the trunk of a car),

because permanent damage can result.

Water Immersion

The Fishnder is waterproof to IEC Standard 60529 IPX7. It can

withstand immersion in 1 meter of water for 30 minutes. Prolonged

submersion can cause damage to the Fishnder. After submersion,

wipe and air dry the Fishnder before reusing.

iv Fishnder 340C Owner’s Manual

IntroductIon > WArnIng

Warning

 This product, its packaging, and its components contain chemicals known to the State of California to cause cancer, birth defects, or reproductive

harm. This Notice is being provided in accordance with California’s Proposition 65. If you have any questions or would like additional information, please refer

to our Web site at http://www.garmin.com/prop65.

 requires the recycling of certain electronics. For more information on the applicability to this product,

see www.erecycle.org.



When navigating, carefully compare information displayed on the Fishnder 340C to all available navigation sources, including information from visual

sightings, and maps. For safety, always resolve any discrepancies or questions before continuing navigation.

 



For more information go to:

www.garmin.com/aboutGarmin/environment/disposal.jsp.

Fishnder 340C Owner’s Manual 

gettIng stArted > PAckIng lIst And oPtIonAl AccessorIes

GettInG started

Before installing and using your Fishnder 340C, check to see that

your package includes the following items. The package number

is on the outside of the box. If any parts are missing, contact your

Garmin dealer immediately.

Packing List

Standard Package (010-00505-00)

• Fishnder 340C unit

• Tilt/swivel mount

• 6-foot data/power cable

• Owner’s manual

• Quick reference guide

• Flush mount template

• Protective cover

• Flush mount hardware kit

Optional Package (010-00505-01)

• Standard package

• Dual beam (14°/45°) plastic trolling motor/transom mount

transducer with depth and temperature and an attached

30-foot cable

Optional Package (010-00505-02)

• Standard package

• Dual frequency (200/50kHz) plastic transom mount

transducer with depth and temperature and an attached

30-foot cable

Optional Package (010-00505-03 with Worldwide

Language Support)

• Standard package

• Dual frequency (200/50kHz) plastic transom mount

transducer with depth and temperature and an attached

30-foot cable

Optional Accessories

The following optional accessories are available at

www.garmin.com:

• Speed sensors

• Quick-release ush mount kit

• CANet

™ connection kit

• Optional transducers and transducer accessories

 Fishnder 340C Owner’s Manual

gettIng stArted > understAndIng the fIshfInder And sonAr

Understanding the Fishnder and Sonar

The Fishnder 340C is a fully automatic, color sonar unit that

allows you to go out on the water and nd sh without having

to congure a lot of settings. However, you can customize each

setting as you prefer.

If you have used a Fishnder before, you might already know how

to interpret the sonar information on the screen, so you can skip

this section. If you have not used a Fishnder before, you might

want to learn a bit about sonar: what it is, how it works, and what

you might see on the Fishnder 340C screen. This manual provides

a general understanding of those things that you need to know

about sonar that can help you interpret the screen and nd the sh.

Understanding Sonar

During installation, you connect your Fishnder 340C to a

transducer. The transducer uses sound to determine information

about what is in the water beneath your boat. Then the transducer

sends the information to your Fishnder to be shown on the screen

for you to view and interpret.

The transducer sends sound waves down into the water in a cone

shape, similar to a ashlight beam (covering a smaller circular area

at the top and angling out to a larger circular area at the bottom).

These sound waves reect off of any object that they hit, and then

the waves travel back up to the transducer. These objects could

be sh, branches, the bottom, or any other object that has density

that is different from the water. The transducer receives the sound

wave information, and then sends the information to the Fishnder.

The Fishnder shows the information on the screen for you to see

and interpret. The type of transducer and settings that you choose

determine how the information appears on the screen.

Using Dual Frequency

Dual frequency works best for deep water (for example, off-shore)

applications. The 200 kHz frequency allows you access to great

detail about what is underneath your boat. The 50 kHz frequency

provides less detailed information, but penetrates to greater depths

with the same power. You can choose either or both frequencies to

get the information that you want. If you choose dual frequency,

the transducer alternates between the 50 kHz and 200 kHz signals.

This capability allows you to see the best picture available at any

depth.

Fishnder 340C Owner’s Manual 3

gettIng stArted > understAndIng the fIshfInder And sonAr

Using Dual Beam

Dual beam works best for shallow water (for example, inland)

applications. A dual beam transducer can transmit a narrow or a

wide beam. The water area covered by the transmitted sound waves

is determined by the beam width of the transducer and the water

depth. The narrow beam provides crisp detail of what is under your

boat, and is very helpful if you are shing in deeper water where

the beam covers more area (for example, at a depth of 30 feet, the

narrow beam covers the area of about a 7-foot circle).

Wide

Beam

Narrow

Beam

The wide beam is more helpful in shallow water, because it gives

you a much wider view of objects in the water, including areas

beyond the sides of your boat. At a depth of 30 feet, the wide beam

covers the area of approximately a 20-foot circle.

Understanding the Fishnder Screen

Experimentation and experience are the keys to successfully

interpreting your Fishnder screen. We recommend that you take

your Fishnder out on familiar water, and spend time learning to

interpret what you see on the Fishnder 340C screen.

Think of the Fishnder screen as if you took a picture from the

side of an aquarium in your home. You can see how deep a sh is

in the water (how close it is to the top or bottom), but you cannot

tell where the sh is located horizontally in the water (whether it is

near the front or the back of the aquarium). Remember this when

you are trying to locate exactly where something is in the water.

4 Fishnder 340C Owner’s Manual

gettIng stArted > understAndIng the fIshfInder And sonAr

Suspended

targets

Bottom

Surface

clutter

Water

depth

Depth

scale

The strongest sonar returns appear on your screen as the most

intense solid color (depending on your selected color scheme; red

is the default). The weakest returns appear as the less intense, less

solid colors (blue is the default).

The bottom of the water is always going to be the strongest

signal, and therefore the most intense color. The bottom is the

continuous, intensely-colored line running across the bottom of

the screen. The Fishnder 340C includes the latest technology in

interpreting bottom signals; it can see through sh, structures, and

thermoclines (shown in the weakest colors). Large schools of sh

or dense structures close to the bottom can affect water depth return

readings.

If the Fishnder is unable to track the bottom for any

reason, the digits which indicate depth ash on and off to alert

you that the Fishnder is not tracking the bottom.

Along the top of the screen, you might see a grouping of intense

colors. This area is surface clutter, which can be caused by waves

or any other sonar interference at the surface of the water. Too

much surface clutter can obscure your view of sh. You can turn

down the Gain setting to reduce this surface clutter.

Between the bottom and the surface clutter, you see suspended

targets in the previous illustration. Here, the targets appear as

arches. Actual suspended target returns might not always appear

as perfect arches, due to the speed, sh orientation, or other

conditions. You can turn on the Fish Symbols setting if you want to

see suspended targets indicated by a sh shape.

The strength of the sonar return can also help you interpret the

hardness of the bottom of the water. The thicker the bottom line,

the harder the bottom.

Hard Structure Soft Structure

Fishnder 340C Owner’s Manual 

InstAllIng the fIshfInder 340c > selectIng A locAtIon for the fIshfInder

InstallInG the fIshfInder 340c

To ensure the successful operation of your Fishnder 340C, you

must properly install the Fishnder and all of its related parts.

To install and use your Fishnder, you must do the

following:

1. SelectaproperlocationfortheFishnder.

2. MounttheFishnder.

3. Installyourtransducer.

4. Connect to your power source.

5. Test the installation.

Each of these steps is described in detail in the following sections.

Selecting a Location for the Fishnder

Consider the following when you select an installation location:

• Provides optimal viewing as you operate your vessel.

• Allows easy access to the unit’s keypad.

• Is strong enough to support the weight of the Fishnder and

protect it from excessive vibration or shock.

• Allows room for the routing and connection of the

power/

data and transducer cables. There should be at least a 3-inch

(8 cm) clearance behind the case.

DO NOT mount the unit in an area that is exposed to extreme

temperature conditions.

The temperature range for the Fishnder 340C is 5°F

to 131°F (-15°C to 55°C). Extended exposure to temperatures

exceeding this range (in storage or operating conditions) may

cause failure of the LCD screen. This type of failure and related

consequences are NOT covered by the manufacturer’s limited

warranty.

To get the best possible performance from your Fishnder 340C:

• Read the instructions rst, and then follow the instructions to

install the unit.

• Gather the appropriate fasteners and tools.

• Verify that all cables can reach the unit mounting location

and the transducer.

• Wear safety goggles and a dust mask when drilling, cutting,

or sanding.





 Fishnder 340C Owner’s Manual

InstAllIng the fIshfInder 340c > MountIng the fIshfInder

Mounting the Fishnder

There are two possible installation methods for your Fishnder:

• You can mount the Fishnder onto a bracket that attaches to

the console or overhead.

• You can ush mount the Fishnder into a at panel.

Surface Mounting the Fishnder

The Fishnder 340C’s compact, waterproof case is suitable for

mounting in exposed locations or at the nav station. The Fishnder

comes with a tilt/swivel mounting bracket that can be used for

console or overhead mounting.

Mounting the Bracket Assembly

—drill, screwdriver (Phillips or standard), and

one of the following:

• Three #8 (4 mm) pan-head machine bolts with matching nuts

and washers and a 5/32" (5 mm) drill bit.

• Three #8 pan-head self-tapping screws and a 1/16

" drill bit

for drilling starter holes.

Use a pan-head machine bolt or self-tapping screw to secure the

swivel base. If you use a screw with a countersunk head, you risk

damaging the mounting bracket.

To mount the bracket assembly:

1. Using the swivel base as a template, mark the location of

the three holes that secure the bracket to the mounting

surface.

2. Drill the mounting holes.

• Ifyousecurethebasewithmachinebolts,drillthree

5/32"(5mm)holesatthelocationsyoumarked.

• Ifyousecurethebasewithself-tappingscrews,drill

starterholesatthelocationsyoumarked.Donotmake

thestarterholesdeeperthanhalfthescrewlength.

3. Secure the swivel base with three bolts or screws. DO NOT

OVERTIGHTEN.

4. Placetheswivelmountbracketovertheswivelbaseand

secure it with the short knob.

Fishnder 340C Owner’s Manual 

InstAllIng the fIshfInder 340c > MountIng the fIshfInder

Installing the Unit on the Mounting Bracket

To install the Fishnder on the mounting bracket:

1. AligntheslotonthebackoftheFishnderwiththelong

mountingknob,andslidetheFishnderintoplace.If

necessary,adjustthelongknobtospreadthebracketarms

apart.(Turncounter-clockwisetowidenthebracketarms

andclockwisetotighten.)

2. AdjusttheFishnderangle,andtightenthelongmounting

knob until snug.

3. Rotate the swivel mount bracket by twisting it left or right.

Thebracketclicksasyouturnit.Selectagoodviewing

angle,andthentightenallknobs.

4. Connect the power/dataandtransducercablestotheback

oftheFishnder,makingsurethelockingringsarefully

tightenedonbothconnectors.

Flush Mounting the Fishnder

You can ush mount the Fishnder 340C into a at panel.

• Select an appropriately sized location for the unit.

• Use the Flush Mount Template provided in the box to

determine a location.

• Check that all cables reach the unit mounting location.

• Always wear safety goggles and a dust mask when drilling,

cutting, or sanding.

Included mounting hardware

—(4) 3 mm studs, (4) at washers,

and (8) 3 mm hex nuts.

—center punch, drill, 1/8" (3 mm) drill bit,

3/8" (6 mm) drill bit, jig saw, 1/16" (2 mm) Allen wrench, and 9/32"

(7 mm) wrench.

 Fishnder 340C Owner’s Manual

InstAllIng the fIshfInder 340c > MountIng the fIshfInder

To ush mount the Fishnder 340C:

1. TrimtheFlushMountTemplate,andtapeittothechosen

location.

2. Usingacenterpunch,indentthecenterofeachmounting

hole location.

3. Usingan1/8"(3mm)drillbit,drillthefourmountingholes.

4. Usinga3/8"(6mm)drillbit,drillaholeforalocationto

begin cutting the mounting surface.

5. Usingthejigsaw,cutthemountingsurfacealongtheinside

ofthedashedlineindicatedonthetemplate.Beverycareful

when cutting this hole, there is only a small amount of

clearancebetweentheFishnderandthemountingholes.

Youcancutslightlyinsidetheindicatedlineandthensand

orlethepanel,asneeded,toobtainthebestt.

6. InstallthefourmountingstudsintotheFishnderby

screwingtheshortersectionintothebackoftheFishnder.

Use a 1/16" (2 mm) Allen wrench to tighten the mounting

studsuntilthestopcontactsthecase.Becarefulnotto

overtighten,becausethiscandamagethemountingstud!

Thestudshaveareusablethread-lockingpatchpre-applied

from the factory.

7. PlacetheFishnderintothecutoutinthemountingsurface.

8. Placewashersoverthemountingstuds,andthenthread

ononehexnutpermountingstud.Tightenallfouruntilthe

Fishnderissnugagainstthemountingsurface.Installand

tightenthesecondhexnutonallfourmountingstudstolock

therstoneintoplace.

Mounting Surface (Back View)

Hex nut

Washer

Studs

Fishnder 340C Owner’s Manual 

InstAllIng the fIshfInder 340c > MountIng the trAnsducer

Mounting the Transducer

Proper transducer installation is key to getting the best performance

from your new Fishnder. If the transducer lead is too short,

extension cables are available from your Garmin dealer. Coil and

secure any excess cable.

DO NOT cut the transducer lead or any part

of the transducer cable, because cutting the transducer

cable voids your warranty. The cable cannot be spliced

and connected to any existing (Garmin or non-Garmin)

transducer cables.

The following pages contain tips and basic installation instructions

for some popular transducers. Detailed installation instructions are

provided in the transducer kits. Some transducers might have to be

installed by a professional marine installer.

Assembling the Transducer

To assemble the transducer:

1. Inserttherubberwasherandplasticspacerintothe

transduceratthesametime.DONOTlubricatetherubber

washer.

2. Routethecabletowardthebackofthetransducer.Slidethe

transducerintothetransducermount.

3. Placea5mmatwasheronthe10-32x1.75"screw,and

insertthescrewthroughthetransducermount,spacer,and

rubber washer.

4. Placetheremaining5mmatwasherontheexposedend.

Installthe10-32locknutngertight.Youcantightenthe

transducerfurtherafterinstallationontheboat.

Back of the transducer

Cable tie slot

0 Fishnder 340C Owner’s Manual

InstAllIng the fIshfInder 340c > MountIng the trAnsducer

Mounting the Transducer on a Trolling Motor

(Dual Beam Only)

To mount the transducer on a trolling motor:

1. Slidethelargecabletiethroughtheslotonthetransducer

mount (see the illustration on page 9)withtheridgesofthe

bandfacingupuntilequallengthsextendonbothsidesof

the mount. (NOTE:Forcoldwater,orheavytimberordebris

areas,ametal4-5"wormgearclampisrecommended.)

2. Positionthemountgasketonthecurvedtopofthe

transducermount.

Cable tie

Front of the transducer

3. Placethetransducerassemblyagainstthemotorbodyof

thetrollingmotor,withthefrontofthetransducerpointed

away from the trolling motor propeller.

4. Wrapthetwoendsofthecabletiearoundthemotorbody.

Placethepointedendofthecabletiethroughthefastener

holeontheoppositeendandpullitthroughuntilitissnug

but not tight. (The cable tie clicks when you pull it.)

5. Positionthetransducersothatitisparallelwiththebottom

wheninuse,andmakesurethegasketisalignedproperly.

Pullthecabletieenduntiltight.Trimofftheexcessif

necessary.Tightenthe10-32lockingnutuntilittouchesthe

mountingbracket,andthentighten1/4turnmore.(Donot

overtighten.)

6. Routethe30-foot(9m)transducercableusingthesupplied

cable ties to secure the cable to the motor shaft. You can

lltheforward-facingportion(exceptthecabletiepocket)

ofthetransducermountwithsealanttoavoidaccumulating

debris.

Fishnder 340C Owner’s Manual 

InstAllIng the fIshfInder 340c > MountIng the trAnsducer

Mounting the Transducer on a Transom

When selecting a transom mount location, consider the following

for optimal performance:

• For your sonar to operate properly, the transducer must be

located in calm water. DO NOT mount the transducer behind

strakes, rivet lines, struts, ttings, water intake, discharge

ports, eroding paint, or anything that creates turbulence.

• Mount the transducer as close to the center of the boat as

possible.

• DO NOT cut the transducer lead. (This voids your warranty.)

• DO NOT mount the transducer in locations where it might

be jarred when launching, hauling, trailering, or storing.

• DO NOT mount the transducer in the path of the prop on

single-drive boats. The transducer can cause cavitation that

can degrade the boat’s performance and damage the prop. On

twin-drive boats, mount the transducer between the drives, if

possible.

$ONOTMOUNTTHETRANSDUCERDIRECTLYINTHE

PATHOFTHEPROP4HETRANSDUCERCANCAUSE

CAVITATIONTHATMAYDEGRADETHEBOATS

PERFORMANCEANDDAMAGETHEPROP

-AKESURETHATTHETRANSDUCERISBELOW

WATERLEVELWHENTHEBOATISONPLANE

ATHIGHSPEED

!PPLYMARINESEALANTTOALL

SCREWTHREADSTOPREVENTWATER

FROMSEEPINGINTOTHETRANSOM

-OUNTTHETRANSDUCERCABLE

COVERWELLABOVETHE

WATERLINE

4RANSDUCERSHOULDEXTEND

BELOWFIBERGLASSHULLOR



BELOWALUMINUMHULL

-OUNTTHETRANSDUCERPARALLELWITHTHEBOTTOM

533*AYHAWK

DO NOT mount the transducer behind strakes, struts,

ttings, water intake or discharge ports, or anything that creates

air bubbles or causes the water to become turbulent. The

transducer must be in clean (non-turbulent) water for optimal

performance.

 Fishnder 340C Owner’s Manual

InstAllIng the fIshfInder 340c > MountIng the trAnsducer

 (not included)—drill, 3/8" wrench or socket, 5/32" and

1/8" drill bits, masking tape, #2 Phillips screwdriver, and marine

sealant.

To mount the transducer on a transom:

1. Positionthetransducermountattheselectedtransom

location.Makesurethetransducerisparallelwiththe

water line. Mark the center locations of each hole on the

transducermount.

2. Usinga5/32"bit,drillthepilotholesapproximately1"

(25mm)deepatthemarkedlocations.Toavoiddrillingthe

holestoodeep,wrapapieceoftapearoundthebitat1"

from the point of the bit.

3. Applymarinesealanttothe5x30mmscrews.Attachthe

transducerassemblytothetransomusingthe5x30mm

screws.Adjustthetransducerassemblytoextendbeyond

the bottom of the transom approximately 1/8" (3 mm) on

berglasshullsor3/8"(10mm)onaluminumhulls.Adjust

thetransducerassemblytobealignedparallelwiththe

water.

4. Tightenthe10-32lockingnutuntilittouchesthe

mountingbracket,andthentighten1/4turnmore.(Donot

overtighten.)

5. Placetherstcableclamponthetransducercable

approximatelyonethirdofthedistancebetweenthe

transducerandthetopofthetransom.

 Markthelocation.Usinga1/8"bit,drillapilothole

approximately3/8"(10mm)deep.

6. Attach the cable clamp using a 4 x 12 mm screw. Coat the

screw with marine sealant before installation. Repeat steps

5and6usingtheothercableclamp.

7. Routethetransducercable,asneeded,totheFishnder.

DONOTCUTTHECABLE.Avoidroutingthecablewith

electrical wires or other sources of electrical interference.

Level

Drill pilot holes here.

Vertical

Bottom of the transom

Align with the transom

bottom. The transducer

should extend /"

below berglass hulls

or 3/" below aluminum

hulls.

Keep it parallel with the water line.

Fishnder 340C Owner’s Manual 3

InstAllIng the fIshfInder 340c > MountIng the trAnsducer

Shoot-Thru-Hull Installation

To avoid drilling a hole to mount a thru-hull transducer, a

transducer can be secured with epoxy inside a boat (shoot-thru-

hull installation). This type of installation can provide better

noise reduction and allow you to use a higher Gain setting. For

a transducer to be mounted inside the hull (shoot-thru, not thru-

hull), the boat must be berglass, with no core. Contact your boat

manufacturer if you are unsure. Professional installation might be

necessary. Be sure to always wear a dust mask and safety goggles.

Some transducers are specically designed to be mounted inside a

berglass hull. The standard plastic transom mount transducer can

also be mounted using this method. If using a temperature sensing

transducer, the temperature shown reects the hull temperature.

Selecting a Location for a Shoot-Thru-Hull Installation

When installing a transducer, the installation location must be the

following:

• Solid berglass, without any air bubbles, laminates, llers, or

dead air space.

• In an area of clean (non-turbulent) water at all speeds.

• The location must not be over any strakes or behind any

obstruction on the hull that would create turbulence at speed.

Many modern hulls have a dedicated pocket for

shoot-thru-hull transducer installation. If you are unsure if your

hull is equipped with a pre-located pocket, contact your hull

manufacturer.

To test the location:

1. FabricateatestdevicefromasectionofPVCpipeoracan,

as shown in the following illustration.

2. Temporarilysealthetestdevicetothehullwithcaulkingor

RTVsealer,andllwithwaterorlightmineraloil.

3. Placethetransducerinthewater,pointeddirectlyat

thebottomandweightitdown.Settheunitforoptimum

performance.Ifthesonarperformanceissignicantly

degraded,anotherlocationmustbetested.

Testing the Location

Strip caulk

or RTV sealer

Hull surface

PVC pipe

or a can

Weight the transducer to

hold it in place.

Fill a pipe or can with water

or a light mineral oil.

4 Fishnder 340C Owner’s Manual

InstAllIng the fIshfInder 340c > MountIng the trAnsducer

To permanently install the transducer:

1. Lightlysandthesurfaceofthehullandfaceofthe

transducerwith400gritwetordrysandpaper.

2. Buildadamusingstripcaulkabout1/4"(6mm)tall.Pour

about 1/8" (3 mm) of two-part, slow-cure epoxy into the

dam.

3. Placethetransducerintheepoxy,turningthetransducerto

work out any air bubbles.

4. Weightthetransducerinplace,andallowittocurefor

24 hours.

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