Airmar P79 Installation Instructions

In-Hull, Adjustable Angle Transducer

Model P79

U.S. Patent No. 6,201,767. EP 1 118 074

Applications

• Fiberglass hulls only

• Recommended for high-speed powerboats and racing sailboats

• Accommodates a deadrise angle up to 22°

Tools & Materials

Safety goggles

Dust mask

Adhesive tape

Pole

Detergent (some installations)

Weak solvent (such as alcohol)

Disk sander (some installations)

Thin sealable plastic bag (some installations)

Cable ties (some installations)

Water-based lubricant (such as K-Y® jelly) (some installations)

Angle finder or digital level

Carpenter’s square

Pencil

Silicone sealant (such as GE Silicone I or Silicone II)

Screwdriver

Petroleum jelly (such as Vaseline® brand)

Propylene glycol (non-toxic antifreeze/coolant) 71ml (2.4 fl. oz.)

Level

Grommet(s) (some installations)

Installation in a cored fiberglass hull (see page 4):

Drill

Hole saw

100mm or 4"

Miniature disk sander

Casting epoxy (Polypoxy #7035/7040) or resin

Paper cup

Stirrer

Mounting Location

About Fiberglass Hulls

The fiberglass hull below the transducer must be solid. Since the 

hull absorbs acoustic energy, transmitting through the hull 

reduces the transducer’s performance. Fiberglass hulls are often 

reinforced in places for added strength or to reduce weight. These 

cored areas contain balsa wood or structural foam which are poor 

sound conductors. Do not locate the transducer over coring.

Placement

CAUTION: Do not mount the transducer near water intake or 

discharge openings or behind strakes, fittings, or hull irregularities 

that will disturb the water flow.

Choose a location:

• Where the fiberglass is solid (no air bubbles are trapped in the

fiberglass resin) and where no coring, flotation material, or dead

air space is sandwiched between the inside skin and outer skin

of the hull.

• Where the hull below the transducer will be in contact with the

water at all times.

• Where the water flowing under the hull is smoothest with a

minimum of bubbles and turbulence (especially at high speeds).

• Away from interference caused by power and radiation sources

such as: the propeller(s) and shaft(s), other machinery, other

echosounders, and other cables. The lower the noise level, the

higher the echosounder gain setting that can be used.

• Where the transducer beam will not be blocked by the keel or

propeller shaft(s).

• Where the deadrise angle does not exceed 22°.

• Where there is space inside the vessel for the height of the unit,

tightening the locking ring, and installing the transducer.

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

Part No._________________Date___________Frequency________kHz

INSTALLATION INSTRUCTIONS

WARNING: Always wear safety goggles and a dust 

mask to avoid personal injury.

CAUTION: The fiberglass hull below the transducer 

must be solid. The transducer will not transmit through 

coring material such as foam or balsa wood.

CAUTION: Do not use an epoxy adhesive because it 

is too brittle.

CAUTION: Never pull, carry, or hold the transducer by 

the cable. This may sever internal connections.

CAUTION: Never use solvents. Cleaners, fuel, 

sealants, paint, 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.