Airmar TM256 Owner's Manual & Installation Instructions

Brand: Airmar

Model: TM256

Type: Owner's Manual & Installation Instructions

This manual is also suitable for

TM260

17-299-01 rev. 01 1/02

CAUTION

NEVER USE SOLVENTS

Cleaners, fuel, paint, sealants, and other products may

contain strong solvents, such as acetone, which attack

many plastics greatly reducing their strength.

IMPORTANT

: Please read these instructions

completely before proceeding with the installation.

These directions supersede any other instructions in

your instrument manual if they differ.

Transom Mount 1kW Depth Transducer

Models: TM256, TM260

See cable tag: Part #________________Date___________Freq._____

Applications

• Sport ﬁshing vessels

• Good operation up to 30kn (35MPH)

•

Not

recommended for high-speed inboard powerboats

• Bracket protects the transducer from frontal impact only

Tools and Materials

Pencil

Safety goggles

Dust mask

Saw (some installations)

File (some installations)

Sandpaper (some installations)

Wrench: 3/8"

Electric drill

Drill bits:

Bracket holes 4mm, #23,

9/64"

Fiberglass hull chamfer, countersink, 6mm,

1/4"

Transom hole (optional) 19mm

3/4”

20mm

13/16"

Furuno, Raymarine only

Cable clamp holes 3mm

7/64"

OWNER’S GUIDE & INSTALLATION INSTRUCTIONS

Figure 1. Mounting location on single drive boat

15cm (6")

minimum beyond

swing radius

hull projection:

0-3cm (0-1/8")

Figure 2. TM256

Masking tape

Marine sealant

Screwdrivers

Straight edge

Stainless steel bolts, nuts, and washers (2 each) 6mm

1/4"

Zip-ties

Water based anti-fouling paint (

mandatory in salt water

)

Mounting Location

General Guidelines

• Mount on the side of the transom where the propeller is rotating

downward (see Figure 1).

• The transducer should be located so that the water passing

over the transducer does not cause a ﬂow disturbance to the

propeller.

• The transducer

must

be submerged in aeration-free and

turbulence-free water.

Do not

mount the transducer in an area

of turbulence or bubbles: near water intake or discharge

openings; behind strakes, struts, ﬁttings, or hull irregularities;

behind eroding paint (an indication of turbulence).

• Avoid mounting the sensor where the boat may be supported

during trailering, launching, hauling, or storage.

• Ideally, mount the bracket above the waterline to minimize the

build up of marine growth. It may be desirable to mount the

bracket farther from the keel than recommended in Figure 1.

• Allow enough headroom above the bracket for the transducer to

be raised into the “up” position and the “released” position

(see

Figure 2). If there is too little headroom, the support tube

must

shortened (see “Shortening the Support Tube” on page 2).

“Up” position

—The bracket is factory pre-set to provide a

vertical travel of 77mm (3") between the “up” and “down”

positions. The vertical travel can be adjusted by moving the

lower

latch pin to another set of adjustment holes. With the lower

latch pin in the

bottommost

set of holes, the support tube

requires 30cm (12") of headroom above the bracket in the “up”

position.

The upper latch pin must be inserted through the

topmost holes of the support tube for the transducer to release.

“Released” position

—The transducer makes an arc of 110

“up” “down” “released”

transducer

face

parallel to

waterline

“down”

position

sensor in

Type of Boat

•

Single drive

—Mount a minimum of 15cm (6") beyond the

swing radius of the propeller (see Figure 1).

•

Twin drive

—Mount outside the drives a minimum of 15cm (6")

beyond the swing radius of the propeller.

•

Trim tabs

—Mount inside the trim tab, space permitting.

•

Drive extension

—Mount as far to the side as is practical.

•

Swim platform

—If the platform interferes with the movement of

the transducer, make a cutout to accommodate the transducer

and/or shorten the support tube.

•

Stepped transom

—Mount the transducer on the transom

above the step. Use a straight edge to position the underside of

the transducer even with the underside of the transom (see

Figure 3).

Shortening the Support Tube

WARNING

: The upper latch pin must be inserted through the

topmost

holes of the support tube for the transducer to release.

Failure to pin the support tube through the topmost holes can

result in damage to the bracket if it releases.

If the transducer assembly is too high for the selected mounting

location, the support tube

must

be shortened.

1.Remove the upper latch pin. Slide the support tube out of the

bracket (see Figure 4).

2.The support tube can be shortened in 25mm (1") increments up

to a maximum of 28cm (11"). Determine the amount to be

shortened from the

top

of the tube. Draw a line against the bot-

tom edge of the chosen hole

plumb

with the row of holes.

not cut the bottom of the support tube

(see Figure 5).

Warning

: Always wear safety goggles and a dust mask.

3.Cut the

top

of the support tube to the desired length.

4.File and sand the cut edge to remove sharp edges and burrs.

5.Replace the support tube in the bracket. Secure it by sliding the

upper latch pin through the

topmost

adjustment holes (see

Figure 4).

The upper latch pin must be inserted through the

topmost holes of the support tube for the transducer to release.

Installation

Caution

: Never pull, carry, or hold the transducer by the cable as

this may sever internal connections.

Assembling and Positioning

1.Thread the cable through the support tube (see Figure 4).

2.Using the 3 hex socket cap screws and a 3/8" wrench, attach

the transducer to the mounting shoe.

Do not tighten the center

screw at this time

. The transducer angle will be adjusted later.

3.With the transducer in the “down” position, hold the transducer

assembly at the selected location on the transom. Locate the

bottom of the transducer about 0–3cm (0–1/8") below the

bottom edge of the transom (see Figure 1).

4.Depending on the angle of your transom, the bracket may need

a shim(s) for the transducer to clear the transom when it is

raised and lowered (see Figure 4). Check for clearances with

the transducer in the “up”, “down”, and “released” positions (see

Figure 2). Experiment with the shim(s) provided until there is

sufﬁcient clearance while maintaining the transducer face

parallel to the water surface. When you are satisﬁed with the

mounting location, use a pencil to draw the outline of the

mounting plate on the transom (see Figure 6).

Note: The bracket is factory pre-set to provide a vertical travel of

77mm (3") between the “up” and “down” positions. The vertical

travel can be adjusted by moving the

lower

latch pin to another

set of adjustment holes.

Figure 3. Stepped transom

Figure 6. Mounting plate and screw locations

correct incorrect

hull

screw

reinforcement

bolt hole (2)

Figure 4. TM256 assembly

upper latch pin

bracket

latch release line

latch lever

lower latch pin

transducer

hoist line

hinge pin

safety ring

mounting plate

support tube

mounting shoe

adjustment hole

cable

location (4)

Figure 5. Shorten support tube

immediately

below a hole,

plumb with the

row of holes

shim (2)

do not

cut

bottom (with

small holes)

(17 pairs)

cut top only,

screw recess (2)

Mounting

1.Separate the mounting plate from the bracket by removing one

safety ring and withdrawing the hinge pin (see Figure 4).

2.Position the mounting plate on the transom over the pencil

outline with the shim(s) in place. (To hold the shim(s) in place,

tape it to the bracket.)

Be sure

the bracket is plumb with the

waterline (see Figure 6).

Warning

: Always wear safety goggles and a dust mask.

3.Using a 4mm, #23 or 9/64" bit, drill four holes, 30mm (1-1/4")

deep, at the selected location.

Be sure

the drill is oriented

parallel to the keel and at right angles to the transom. Drill

through any shim(s).

Do not drill the holes for the

reinforcement bolts at this time

Fiberglass hull

—To minimize surface cracking, chamfer the

gelcoat. If a chamfer bit or countersink bit is not available, start

drilling with a 6mm or 1/4" bit to a depth of 1mm (1/16").

Note: To prevent drilling too deeply, wrap masking tape around

the bit the desired distance from the point.

4.Apply marine sealant to the four #10 x 1-1/2" self-tapping

screws to prevent water seepage into the transom. Fasten the

mounting plate and any shim(s) to the hull with the screws

positioned at the bottom of each slot.

5.Attach the transducer assembly to the mounting plate with the

hinge pin and safety ring (see Figure 4).

6.Check again for clearances with the transducer in the “up,

“down”, and “released” positions.

7.Using a straight edge, sight the underside of the transducer

relative to the underside of the hull (see Figure 7).

Being sure

the transducer face is nearly parallel to the water surface, adjust

the angle of the mounting shoe to make the aft end of the

transducer 3mm (1/8") below the rounded forward end. Tighten

the center screw.

8.The large diameter line is the hoist line. Tie it to the upper latch

inside

the support tube with a boline knot. The small

diameter line is the latch line. Tie it to the latch lever with a

boline knot (see Figure 4).

You may want to hoist the transducer into the “up” position at

planing speeds [especially above 30kn (35MPH)]. To operate

the latch release line and the hoist line, it may be necessary to

devise a system of sheaves and eyes to a remote location.

Testing on the Water

1.Test the transducer at 200kHz with the engine off.

2.Become familiar with your echosounder’s performance at a

speed of 4kn (5 MPH).

3.Gradually increase the boat speed and observe the gradual

decline of performance due to turbulent water ﬂowing over the

transducer’s face.

Note: As the speed increases the performance at 50kHz will

deteriorate more rapidly because more acoustic noise is

generated at low frequencies.

4.If the decline of performance is sudden (not gradual), identify

the boat speed at which the onset occurred. Return the boat to

this speed, then gradually increase speed while making

moderate turns in both directions.

5.If the performance improves when turning, the transducer’s

position probably needs adjustment. The transducer is probably

in turbulent or aerated water. Move the transducer farther down

into the water in increments of 12mm (1/2"). If the performance

does not improve satisfactorily, move the transducer closer to

the centerline (keel). Fill unused screw holes with marine

sealant.

Bolting the Assembly

When you are satisﬁed that the mounting location provides good

performance, reinforce the mounting bracket with bolts, washers,

and nuts (not supplied). Since transom thicknesses vary and most

installations require a spacer, the installer must determine the

appropriate length bolt.

1.Separate the bracket from the mounting plate by removing one

safety ring and withdrawing the hinge pin (see Figure 4).

Figure 7. Transducer angle (TM256 shown)

Warning

: Always wear safety goggles and a dust mask.

2.Drill the two reinforcement bolt holes through the hull and

spacer (see Figure 6).

3.Apply sealant to the bolt threads to prevent water seeping into

the transom. Tap the bolts into place. Apply the washers and

nuts inside the transom.

4.Reattach the bracket to the mounting plate with the hinge pin

and safety ring.

Cable Routing

Route the cable over the transom for a detachable installation. For

permanent mounting, route the cable through a drain hole or

through a new hole drilled in the transom

above the

waterline

Caution

: Never cut the cable or remove the connector; this will

void the warranty.

Warning

: Always wear safety goggles and a dust mask.

1.If a hole must be drilled

through the transom,

choose a location

well

above the waterline

(see

Figure 8). Check for

obstructions such as trim

tabs, pumps, or wiring

inside the hull. Mark the

location with a pencil. Drill

the hole using the

appropriate size bit to

accommodate the

connector.

2.Route the cable over

through the transom.

3. On the outside of the hull,

secure the cable against

the transom using the cable

clamps. Position one cable

clamp 15cm (6") above the

bracket. Mark the mounting

hole with a pencil.

Figure 8. Cable routing

cable

clamps

cable

cover

15cm (6")

4" of

slack

10cm

4.Position the second cable clamp halfway between the ﬁrst

clamp and the cable hole. Mark this mounting hole.

5.If a hole has been drilled through the transom, open the large

slot in the transom cable cover. Position the cover over the

cable where it enters the hull. Mark the two mounting holes.

6.At each of the marked locations, use a 3mm or 1/8" bit to drill a

hole 10mm (3/8") deep. To prevent drilling too deeply, wrap

masking tape around the bit 10mm (3/8") from the point.

7.Allow about 10cm (4") of slack in the cable below the lower cable

clamp to accommodate the sensor in the “released” position.

8.Apply marine sealant to the threads of the #6 x 1/2" self-tapping

screw to prevent water from seeping into the transom.If you

have drilled a hole through the transom, apply marine sealant to

the space around the cable where it passes through the

transom.

9.Position the two cable clamps over the cable and fasten them in

place. If used, push the cable cover over the cable and screw it

in place.

10.Route the cable to the instrument

being careful

not to tear the

cable jacket when passing it through the bulkhead(s) and other

parts of the boat. To reduce electrical interference, separate the

sensor cable from other electrical wiring and the engine(s). Coil

any excess cable and secure it in place with zip-ties to prevent

damage.

11.Refer to your echosounder owner’s manual to connect the

transducer to the instrument.

Checking for Leaks

Warning

: When the boat is placed in the water,

immediately

check for leaks around the screws and any hole drilled in the hull.

Never install a sensor and leave the boat in the water unchecked

for several days.

Anti-fouling Paint

Marine growth can accumulate rapidly on the transducer’s surface

reducing performance within weeks. Surfaces exposed to salt

water

must

be coated with anti-fouling paint.Use

water based

anti-fouling paint only.

Never

use ketone based paint, since

ketones can attack many types of plastic possibly damaging the

transducer.

Apply paint to the transducer and all parts of the bracket up to

100mm (4")

above the waterline

. Repaint every 6 months or at the

beginning of each boating season.

Operation

“Up” position

Store the transducer in the “up” position when it is not in use (see

Figure 2). In the “up” position, the transducer is protected from

impact, but note that

the bracket will not release

. The “up”

position must be used when running at high speed [above 30kn

(35MPH)] to minimize drag. The “up” position will provide very

good ﬁshﬁnding at boat speeds below 6kn (7MPH). Raise the

transducer to the “up” position by pulling on the latch line to

release the latch while pulling on the hoist line to raise the support

tube until the latch engages the lower latch pin (see Figure 4).

“Down” Position

Place the transducer in the “down” position for normal operation.

The bracket will release in this position. To lower the transducer,

pull on the latch line and lower the support tube.

Be sure

that the

latch re-engages with the upper latch pin (see Figure 4).

“Released” Position

When the transducer is in the “down” position and hits an object in

the water, the bracket will release (see Figure 2). Also, when the

boat is making headway, the water exerts drag on the transducer.

As the boat speed increases, the force on the bracket increases

dramatically. Depending on the water conditions and the amount

the transducer projects below the transom, the transducer bracket

will release at about 40kn (46MPH).

After release, the transducer will ride atop the outwash from the

transom and cause minimal drag while the boat is making

headway. The transducer can survive in this condition if the water

is calm. However, pitching and rolling in rough water will stress the

bracket. Also, the transducer will sink at zero boat speed.

The

release feature is not intended to be a substitute for hoisting

the transducer

Caution

: Always reset the transducer in the “down” position as

soon as possible using a blunt pole.

Maintenance and Parts

Removing the Transducer

1.Lower the transducer into the “down” position.

2.Separate the transducer assembly from the mounting plate by

removing one safety ring and withdrawing the hinge pin (see

Figure 4).

3.Remove the bracket by grasping the support tube near the

mounting shoe and pulling away from the boat.

4.Replace the hinge pin and safety ring on the bracket.

Cleaning

Keep the support tube, guides, and rollers free of sand and grit by

washing them with mild household detergent.

Do not

use a

lubricant, since grit will stick to it increasing friction and wear.

If fouling is severe, use a stiff brush or putty knife to remove the

growth,

being careful

to avoid making scratches on the

transducer’s face. Wet sanding the fouled surfaces with #220 or

ﬁner grade wet/dry paper is permissible.

Storage

Avoid extremes of temperature. Low temperatures make plastic

brittle, and although the transducer is designed to withstand

temperatures up to 70

C (160

F), it is best to store the transducer

at a moderate temperature.

Parts

Lost, broken, and warn parts should be replaced immediately and

can be obtained from your marine dealer or instrument

manufacturer:

Bracket Assembly 33-432-01

Transducer Replacement

The information needed to order a replacement transducer is

printed on the cable tag.

Do not

remove this tag. When ordering,

specify the part number, date, and frequency in kHz. For

convenient reference, record this information where indicated

near the top of page one.

AIRMAR

TECHNOLOGY CORPORATION

35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA

■

www.airmar.com

Airmar TM256 Owner's Manual & Installation Instructions

Brand: Airmar

Model: TM256

Type: Owner's Manual & Installation Instructions

This manual is also suitable for

TM260

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Airmar TM256 Owner's Manual & Installation Instructions

This manual is also suitable for

Airmar TM256 Owner's Manual & Installation Instructions

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