Airmar P23 User Manual

INSTALLATION INSTRUCTIONSOWNER’S GUIDE &

Transom-Mount with Integral Release Bracket

Transducer or TRIDUCER® Multisensor

Models: P23, P32

WARNING: Always wear safety goggles and a dust
mask when installing to prevent personal injury.

WARNING: When the boat is placed in the water,
immediately check for leaks around the screws and
any other holes drilled in the hull.

17-122 rev. 07 04/071/11

CAUTION: Never pull, carry, or hold the transducer by
the cable as this may sever internal connections.

CAUTION: Never strike the sensor with anything except
the palm of the hand. Never strike the paddlewheel.

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 the instructions completely
before proceeding with the installation. These
instructions supersede any other instructions in your
instrument manual if they differ.

Applications

• Not recommended for boats with large inboard engine(s)

• Not recommended for stepped hull

• Good operation up to 55kn (63MPH)

• Vertically orients sound beam on hull with deadrise angle up to 30°

• Adjusts to transom angles from 3

• Bracket protects sensor from frontal impact only

Tools & Materials

Safety goggles
Dust mask

Scissors
Masking tape

Electric drill
Drill bits:

Bracket holes 4mm, #23, or 9/64"

Transom hole (optional) 18mm, 11/16", or 3/4"

Cable clamp holes 3mm or 1/8"
Straight edge

Wire cutters (some installations)
Marine sealant (suitable for below waterline)

Screwdrivers
Pencil
Zip-ties

Water-based antifouling paint (mandatory in salt water)

° – 20°

Record the information found on the cable tag for future reference.

Part No._________________Date___________Frequency________kHz

P32

P23

Pretest Temperature & Speed Functions

Connect the sensor to the instrument and spin the paddlewheel.
Check for the approximate air temperature and a speed reading. If
there is no reading(s) or it is inaccurate, check the connections
and test again. If there is still a problem, return the product to your
place of purchase.

Mounting Location

CAUTION: Do not mount in an area of turbulence or bubbles:

near water intake or discharge openings; behind strakes, struts,
fittings, or hull irregularities

CAUTION: Avoid mounting the sensor where the boat may be
supported during trailering, launching, hauling, or storage.

• For the best performance, the sensor must be in contact with
smooth water. To identify an area of clean water, observe the
water flow off the transom while the boat is underway.

• Allow headroom space above the bracket for it to release and
rotate the sensor upward.

• Mount the sensor as close to the centerline (keel) of the boat as
possible to ensure the sensor remains in the water when the
boat is turning.

• Single drive boat—Mount at least 75mm (3") beyond the

swing radius of the propeller (see Figure 2). The starboard
side where the propeller blades are moving downward is
preferred.

• Twin drive boat—Mount the sensor between the drives.

NOTE: Starboard
side of hull where
propeller blades are
moving downward is
preferred.

75 mm (3")
minimum beyond
swing radius

Figure 1. Mounting location on single drive boat

Copyright © 1995 - 2011 Airmar Technol ogy Corp.

Figure 2. Template for starboard side of boat

centerline (keel)

drill here

Align this point with
bottom of transom

drill here

vertical

Installation

Assembling & Positioning

1. Insert the top of the sensor’s pivot posts into the slots on the top
back of the bracket. Rotate the bracket down until the bottom
snaps onto the sensor.

2. Cut out the template (see Figure 2).

3. At the selected location on the starboard side of the hull,
position the template so the arrow at the bottom is aligned with
the bottom edge of the transom (see Figure 3). Being sure the
template is parallel to the waterline, tape it in place.

Hole Drilling

Using a 4mm, #23, or 9/64" bit, drill two holes 22mm (7/8") deep
at the locations indicated. To prevent drilling too deeply, wrap
masking tape around the bit 22 mm (7/8") from the point.
Fiberglass hull—Minimize surface cracking by running the drill in
reverse until the gelcoat is penetrated.

Plastic Shims

parallel to waterline

Align template vertically

Align template arrow with
bottom edge of transom

Figure 3. Template position

AIRMAR

parallel to
waterline

AIRMAR

• Standard transom (13° transom angle)—The bracket is
designed for a standard 13° transom angle. The 9 degree shim
is not needed for this installation. If your boat is capable of

®

speeds above 35kn (40MPH), install the bracket with the 4.5
degree shim, taper down (see Figures 4 and 5). This ensures

that the paddlewheel will be in contact with the water at high
speeds.

• Stepped transom and jet boats (3° transom angle) —Use the
9 degree shim with the taper down (see Figures 4 and 5).

• Small aluminum and fiberglass boats (20° transom angle)—
Use the 9 degree shim with the taper up (see Figures 4 and 5).

• If you are unsure about using the shims—To determine if the
9 degree shim is needed, position the sensor at the selected
location. Using a straight edge, sight the underside of the
sensor relative to the underside of the hull (see Figures 4 and

5). The trailing edge of the sensor should be 1– 3mm (1/16–1/
8") below the leading edge of the sensor or parallel to the
bottom of the hull.

®

13° transom angle

20° transom angle3° transom angle

angle
reversed

slight angle

angle
too steep

slight angle

AIRMAR

®

thin shim

Figure 4. Plastic shims

thick shim

parallel

14° –17° angle

slight angle

Figure 5. Sensor angle adjustment

shim with taper down shim with taper up

2

Mounting & Adjusting

CAUTION: Do not position the leading edge of the sensor lower
than the trailing edge because aeration will occur.

CAUTION: Do not position the sensor farther into the water than
necessary to avoid increasing drag, spray, and water noise and
reducing boat speed.

1. Align the posts on the shim with the two holes in the bracket. Snap
the shim into place.
High-speed operation [above 35 kn (40MPH)]—It may be
necessary to install the bracket with both shims to ensures that
the paddlewheel will be in contact with the water at high speeds.
Remove the posts from the 4.5 degree shim with wire cutters.
Place the 4.5 degree shim, taper down, behind the 9 degree shim.

2. Apply a marine sealant to the threads of the two #10 x 1-1/4"
self-tapping bracket screws to prevent water seepage into the
transom. With the shim(s) in place, screw the bracket to the
hull. Do not tighten the screws completely at this time.

3. Using a straight edge, sight the underside of the sensor relative
to the underside of the hull (see Figure 5). The trailing edge of
the sensor should be 1–3 mm (1/16 – 1/8") below the leading
edge of the sensor or parallel to the bottom of the hull.

4. Using the vertical adjustment space in the bracket slots, slide
the sensor up or down until the bottom left corner of the sensor
projections 3mm (1/8") below the bottom of the hull (see
Figure 6). When you are satisfied with the position of the
sensor, tighten the screws.

Testing on the Water

1. Become familiar with your echosounder’s performance at a
speed of 4kn (5MPH).

2. Gradually increase the boat speed and observe the gradual
decline in performance due to turbulent water flowing over the
transducer’s active surface.

3. If the decline in 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.

4. If the performance improves while turning to the side on which
the sensor is installed, its position probably needs adjustment.
It is probably in aerated water.

To improve performance, try the following one at a time in the
order given.

A. Move the multisensor farther into the water in increments of

3mm (1/8") (see Figure 4).

B. High-speed operation above 35kn (40 MPH) may be

improved by less projection in the water. Move the sensor
upward on the transom.

C.Increase the multisensor’s angle in the water. Install the 4.5•

shim with the taper down (see Figure 5).

D.Move the multisensor closer to the centerline of the boat. Fill

unused screw holes with marine sealant.

Cable Routing

CAUTION: Do not remove the connector to ease cable routing. If
the cable must be cut and spliced, use Airmar’s splash-proof
Junction Box No. 33-035 and follow the instructions provided.
Removing the waterproof connector or cutting the cable, except
when using a water-tight junction box, will void the sensor warranty.

Route the sensor cable over the transom, through a drain hole or
through a new hole drilled in the transom above the waterline.

®

Hull projection:
3mm (1/8")

AIRMAR

cable cover

cable clamp

50mm (2")

Figure 6. Vertical adjustment and cable routing

1. If a hole must be drilled through the transom, choose a location

well above the waterline (see Figure 6). Check for obstructions
such as trim tabs, pumps or wiring inside the hull. Mark the
location with a pencil. Drill a hole using the appropriate size bit
to accommodate the connector.

2. Route the cable over or through the transom.

3. On the outside of the hull secure the cable against the transom
using the cable clamps. Position one cable clamp 50mm (2")
above the bracket and mark the mounting hole with a pencil.

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 in the transom, open the appropriate
slot in the cable cover. Position the cover over the cable where
it enters the hull. Mark the two screw 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 10 mm (3/8") from the point.

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

8. Position the two cable clamps and fasten them in place. If used,
push the cable cover over the cable and screw it in place.

9. 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.

10.Refer to your echosounder owner’s manual to connect the
sensor to the instrument.

Checking for Leaks

When the boat is placed in the water, immediately check for
leaks around the screws and any holes drilled in the hull. Note
that very small leaks may not be readily observed. Do not leave
the boat in the water unchecked for more than three hours.

3

Maintenance

Antifouling Paint

Aquatic growth can accumulate rapidly on the sensor’s surface
reducing performance within weeks. Surfaces exposed to salt
water that do not interlock, must be coated with antifouling paint.
Use water-based antifouling paint only. Never use ketone-based
paint, since ketones can attack many types of plastic possibly
causing damage to the transducer. Apply paint every 6 months or
at the beginning of each boating season.

Cleaning

Clean the assembly with a soft cloth and mild household
detergent. If fouling occurs, use a stiff brush or putty knife to
remove the growth being careful to avoid making scratches on the
transducer face. In severe cases, wet sand the surface with fine
grade wet/dry paper.

Servicing the Paddlewheel

retaining

arm

The paddlewheel must
be oriented correctly to
measure boat speed.

use lower hole

short side of
paddlewheel blade

Figure 7. Orienting the paddlewheel

BOW

AIRMAR

®

CAUTION: The paddlewheel must be oriented correctly to
measure boat speed.

If the P32 paddlewheel becomes fouled or inoperable, it can be
removed for cleaning. Gently push back one retaining arm and
slide the shaft out.

Orient the short side of the paddlewheel blades as shown in
Figure 7. Reinsert the shaft in the lower set of holes by pushing
back on the retaining arms. Be sure the shaft ends are secure in
the retaining arm notches.

Sensor Replacement, Parts & Accessories

The information needed to order a replacement Airmar sensor is
printed on the cable tag. Do not remove this tag. When ordering,
specify the part number, date, and frequency. For convenient
reference, record this information on the top of page one.

Lost, broken, or worn parts should be replaced immediately. The
water-lubricated paddlewheel bearings have a life of up to 5 years
on low-speed boats [less than 10kn (11MPH)] and 2 years on
high-speed vessels. Purchase parts from your marine dealer or
instrument manufacturer.

Paddlewheel Kit 33-007

Bracket & Wedge Kit 20-154-04

Portable Bracket Kit (see Figure 8) 33-173

Figure 8. Portable Bracket Kit 33-173

AIRMAR

®

Obtain parts from your instrument manufacturer or marine dealer.

Gemeco Tel: [phone]

(USA) Fax: [phone]

email: [e-mail]

Airmar EMEA Tel: [phone]

(Europe, Middle East, Africa) Fax: [phone]

email: [e-mail]

®

AIRMAR

4

TECHNOLOGY CORPORATION

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

Copyright © 1995 - 2011 Airmar Technology Corp. All rights reserved.

www.airmar.com