AIRMAR P39 Transom-Mount with Release Bracket Instruction Manual
- June 6, 2024
- AIRMAR
Table of Contents
OWNER’S GUIDE & INSTALLATION INSTRUCTIONS
Transom-Mount with Release Bracket
Transducer or TRIDUCER® Multisensor
Model P39
U. S. Patents: 5,606,253
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.
CAUTION: Never pull, carry, or hold the transducer by the cable as this
may sever internal connections.
CAUTION: Never strike the transducer 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).
- Good operation up to 44kn (50MPH)
- Vertically orients sound beam on hull with deadrise angle up to 30°
- Adjusts to transom angles from 2°-22°
- Bracket protects transducer from frontal impact only
Tools & Materials
Safety goggles
Dust mask
Pencil
Electric drill
Drill bits:
Bracket holes
Transom hole (optional)
Cable clamp holes| 4mm, #23, or 9/64″
18mm, 11/16″, or 3/4″
3mm or 1/8″
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Masking tape
Angle finder
Grommets (some installations)
Marine sealant (suitable for below waterline)
Screwdrivers
Straight edge
Cable ties
Water-based anti-fouling paint (mandatory in salt water)
Record the information found on the cable tag for future reference.
Part No.___Date_Frequency____kHz
Mounting Location
CAUTION: Do not mount in an area of turbulence or bubbles: near water
intake or discharge openings; or behind strakes, struts, fittings, or hull
irregularities
CAUTION: Avoid mounting the transducer where the boat may be supported
during trailering, launching, hauling, or storage.
- For the best performance, the transducer 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 transducer upward (see Figure 1).
- Mounting on the starboard side of the hull where the propeller blades are moving downward is preferred.
- Mount the transducer as close to the centerline (keel) of the boat as possible to ensure the transducer 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).
- Twin drive boat–Mount the transducer between the drives.
Installation
Attaching the Transducer to the Bracket
- Insert the transducer’s pivot posts into the slots in the back of the bracket (see Figure 3).
- 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.
- At the selected location position the transducer, so it projects 3mm (1/8″) below the bottom edge of the transom (see Figure 4).
- 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.
- 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.
- 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
- Insert the two, lock nuts in the slots in the back of the bracket if this has not been done (see Figure 5).
- Apply marine sealant to the threads of the two, #10 x 1-3/4″, self-tapping screws to prevent water seepage into the transom.
- 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.
- 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 13mm (1/161/8″) below the leading edge or parallel to the bottom of the hull.
- 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.
- When you are satisfied with the position of the transducer, tighten the bracket screws.
Attaching the Cover & Speed Sensor or Blank
-
Place the cover on the transducer (see Figure 7). Align the holes in the cover with the holes in the transducer and bracket.
With speed sensor –Be sure the tab on the cover fits under the speed sensor. This will help to lock the cover in place. -
Insert the two machine screws capturing the nuts in the slots in the back of the bracket. Tighten the machine screws until the transducer will stay in the “up” (released) position unaided.
-
No speed sensor –Insert the side rails of the blank into the channels on the back of the transducer. Slide the blank downward. Fasten it in place with the two, #6 x 5/8″, selftapping screws. Be sure to capture the tab on the cover. This will help to lock the cover in place.
With speed sensor –Fasten the speed sensor to the transducer with the two, #6 x 5/8″, self-tapping screws.
Testing on the Water
-
Become familiar with your echosounder’s performance at a speed of 4kn (5MPH).
-
Gradually increase the boat speed and observe the gradual decline in performance due to turbulent water flowing over the transducer’s active surface.
-
If the degradation 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.
-
If the performance improves while turning, the transducer’s 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. Increase the transducer’s angle in the water. Review “Compensating for Transom Angle–Shim” and see Figure 5.
b. Move the transducer deeper into the water in increments of 3mm (1/8″) (see Figure 4).
c. Move the transducer closer to the centerline of the boat. Fill unused screw holes with marine sealant.
NOTE: High-speed operation above 35 kn (40MPH) may require less projection in the water to improve performance. -
Calibration –To match the speed shown on the display to the actual speed of the boat, you may need to calibrate the instrument. Refer to your instrument owner’s manual.
Cable Routing & Connecting
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
transducer warranty.
Route the transducer cable over the transom, through a drain hole, or through
a new hole drilled in the transom above the waterline.
-
If a hole must be drilled through the transom, choose a location well above the waterline (see Figure 4). 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.
-
Route the cable over or through the transom.
-
On the outside of the hull, secure the cable against the transom using the cable clamps. Position a cable clamp 50mm (2″) above the bracket and mark the mounting hole with a pencil.
-
Position the second cable clamp halfway between the first clamp and the cable hole. Mark this mounting hole.
-
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 mounting holes.
-
At each of the marked locations, use a 3mm or 1/8″ bit to drill a hole 10mm (3/8″) deep.
-
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.
-
Position the two cable clamps and fasten them in place. If used, push the cable cover over the cable and screw it in place.
-
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. Use grommets to prevent chaffing. To reduce electrical interference, separate the transducer cable from other
electrical wiring and the engine(s). Coil any excess cable and secure it in place with cable ties to prevent damage. -
Refer to your echosounder owner’s manual to connect the transducer to the instrument.
Checking for Leaks
When the boat is placed in the water, immediately check for leaks around the screws and any other 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.
Operation, Maintenance, Repair & Parts
Releasing the transducer
CAUTION: The screwdriver used to release the transducer must have a blade
no more than 3mm or 1/8″ wide. Only a small blade can be inserted far enough
into the transducer. A larger screwdriver will damage the transducer’s
housing.
- Before installation –If the transducer is snapped onto the bracket but not secured to the hull, use this method. Release the transducer upward by inserting a 3mm or 1/8″ blade screwdriver into one of the slots on the side of the transducer (see Figure 8). Be sure to insert the screwdriver a full 19mm (3/ 4″) into the slot. Lift up on the handle of the screwdriver while lifting up on the transducer.
- After installation –The transducer releases easily when it is fastened to the hull. Give a sharp blow to the bottom of the transducer using the palm of the hand. Never strike the speed sensor.
Anti-fouling Paint
Aquatic growth can accumulate rapidly on the transducer’s surface reducing
performance within weeks. Surfaces exposed to salt water that do not
interlock, must be coated with anti-fouling paint. Use water-based anti-
fouling paint only. Never use ketonebased 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 transducer 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 scratching the transducer’s face. In severe cases, wet sand
the paddlewheel with fine grade wet/dry paper.
Servicing the Speed Sensor
CAUTION: The paddlewheel must be oriented correctly to measure boat speed.
If the paddlewheel becomes fouled or inoperable, it can be removed for
cleaning. Remove the two screws from the speed sensor (see Figure 9). Slide
the speed sensor upward to remove it from the transducer. Grasp the
paddlewheel and pull to access the shaft.
After cleaning, slide the paddlewheel onto the shaft. Orient the short side of
the paddlewheel blades as shown on the side view. Fit the shaft into the holes
in the retaining bars. Slide the assembly into the speed sensor housing.
Reattach the speed sensor.
Transducer Replacement & Parts
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
on the top of page one.
Replace broken or worn parts 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. Some depth/temperature units can be upgraded by adding a speed sensor.
Part
Paddlewheel Kit
Bracket Kit
Speed Sensor Kit| Part Number
33-473-01
33-477-01
33-478-01
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Obtain parts from your instrument manufacturer or marine dealer.
Gemeco (USA)| Tel: 803-693-0777
Fax: 803-693-0477
email: sales@gemeco.com
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Airmar EMEA
(Europe, Middle East, Africa)| Tel: +33.(0)2.23.52.06.48
Fax: +33.(0)2.23.52.06.49
email: sales@airmar-emea.com
35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA
www.airmar.com
Copyright 2003 – 2011 All rights reserved.
References
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