Airmar P39 Owner'S Manual & Installation Instructions Download Page 2

Installation

 Attaching the Transducer to the Bracket

1. Insert the transducer’s pivot posts into the slots in the back of the 

bracket (see Figure 3).

2. With the screw holes aligned, rotate the transducer until it 

snaps onto the bracket.

Hole Drilling

CAUTION

: To prevent drilling too deeply, wrap masking tape 

around the bit 22mm (7/8") from the point.

NOTE: Fiberglass hull

—Minimize surface cracking by running 

the drill in reverse until the gelcoat is penetrated.

1. At the selected location position the transducer, so it  projects 

3mm (1/8") below the bottom edge of the transom (see Figure 4).

2.

Be sure the bottom of the transducer is parallel to the waterline.

 

Using a pencil, trace the bottom of the bracket and both corners 
onto the hull.

3. Remove the transducer and hold the shim against the outline 

you have drawn. Mark the screw holes with an “X” in the

 center 

of each slot.

4. Using a 4mm, #23, or 9/64" drill bit, drill two holes 22mm (7/8") 

deep at the locations indicated. 

Compensating for Transom Angle: Shim

For the best performance, the transducer beam must be aimed 
straight at the bottom. Since the transom of most boats is angled, 
the bracket must compensate for it. Measure the transom angle of 
the boat with an angle finder.

Standard transom

 (13° transom angle)—The bracket is 

designed for a standard 13° transom angle. The shim is not 
needed for this installation. Skip to “Mounting the Bracket”.

Stepped transom and jet boats

 (3° transom angle) —Use the 

shim with the taper 

down

. Place the nuts in the slots in the back 

of the bracket (see Figure 5). Snap the shim into place.

Small aluminum and fiberglass boats

 (20° transom angle)—

Use the shim with the taper 

up

 (see Figure 5). Place the nuts in 

the slots in the back of the bracket. Snap the shim into place.

• If you are unsure about using the shim

—Experiment with the 

shim by following the instructions “Mounting the Bracket” and 
“Checking the Transducer Angle and Projection.”

Mounting the Bracket

1. Insert the two, lock nuts in the slots in the back of the bracket if 

this has not been done (see Figure 5).

2. Apply marine sealant to the threads of the two, #10 x 1-3/4", 

self-tapping screws to prevent water seepage into the transom.

3. Screw the bracket (with the shim if needed) to the hull. 

Do not tighten the screws at this time.

Checking the Transducer Angle & Projection

CAUTION

: Do not position the leading edge of the transducer 

lower than the trailing edge because aeration will occur.

CAUTION:

 Do not position the transducer farther into the water 

than necessary to avoid increasing drag, spray, and water noise 
and reducing boat speed.

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

relative to the underside of the hull (see Figure 6). The trailing 
edge of the transducer should be 1–3mm (1/16–1/8") below the 
leading edge or parallel to the bottom of the hull.

2. Using the vertical adjustment space in the bracket slots, slide 

the transducer up or down (see Figure 4). Be sure the bottom 
left corner of the transducer projections 3mm (1/8") below the 
bottom of the hull. 

3. When you are satisfied with the position of the transducer, 

tighten the bracket screws

.

2

Figure 3. Mounting the transducer on the bracket

pivot post (2)

slot (2)

bracket

transducer

Figure 5. Mounting the bracket with shim 

(20• transom angle shown)

Figure 4. Vertical adjustment and cable routing

50mm (2")

cable cover

Hull projection

3mm (1/8")

parallel to 

cable clamp

detail

of shim

shim

nuts

slot

screws 

(#10 x 1-3/4"

self-tapping)

transducer

waterline

cable

screw

(taper up)

bracket screw (actual size)

(actual size)

Copyright © 2003 - 2011 Airmar Technology Corp.

Copyright © 2003 - 2011 Airmar Technology Corp.

Copyright © 2003 - 2011 Airmar Technology Corp.

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