Airmar T42 User Manual

INSTALLATION INSTRUCTIONSOWNER’S GUIDE &

Thru-Hull, NMEA 0183

High-Precision Temperature

Model T42

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

17-437-01 rev. 03 12/14/10

WARNING: The power must be OFF before wiring if
the instrument is already connected to a power source
to avoid personal injury or death.

WARNING: The power supply voltage must be
12 VDC. Any other voltage may damage the sensor
and/or result in fire, causing damage to the boat,
personal injury, and/ or death.

WARNING: A safe installation requires a 0.5 amp fast­blow fuse or circuit breaker. Failure to do so may result
in fire, causing damage to the boat, personal injury,
and/or death.

WARNING: Immediately check for leaks when the
boat is placed in the water. Do not leave the boat
unchecked for more than three hours. Even a small
leak can allow considerable water to accumulate.

CAUTION: Never install a metal sensor on a vessel
with a positive ground system.

CAUTION: Never install a bronze sensor in a metal
hull because electrolytic corrosion will occur.

CAUTION: Never pull, carry, or hold the sensor by its
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: Read the instructions completely
before proceeding with the installation. These
instructions supersede any other instructions in your
instrument manual if they differ.

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

Part No._________________Date___________

Data
Converter

T42

Applications

• Bronze sensor recommended for fiberglass or wood hull only.

• The hull must be a minimum of 8mm (5/16”) thick at the
mounting location.

Mounting Location

Choose a location where the temperature sensor will be in contact
with the water at all times.

Tools & Materials

Safety goggles
Dust mask
Electric drill
Drill bits: 3mm or 1/8"

21mm or 7/8"
Sandpaper
Mild household detergent or weak solvent (alcohol)
Marine sealant (suitable for below waterline)
Slip-joint pliers
Installation in a cored fiberglass hull (see page 2)

Hole saw for hull interior: 30mm or 1-1/4"

Cylinder, wax, tape, and casting epoxy
Pencil
Grommet(s) (some installations)
Cutting pliers
Wire strippers
Heat-shrink tubing
Heat gun
Phillips screwdriver
Alcohol
Blade screwdrivers
Water-based anti-fouling paint (mandatory in salt water)

hull nut

hull

Figure 1. Bedding and installing

Copyright © 2005 - 2010 Airmar Technol ogy Corp. Copyright © 2005 Airmar Technology Corp.

bedding

9- 12 mm

pour in
casting
epoxy

hull thickness

(3/8-1/2")
larger than the
hole through the
hull’s outer skin

Figure 2. Preparing a cored fiberglass hull

inner skin

core

outer skinsolid or hollow cylinder

Sensor Installation

Hole Drilling

Cored fiberglass hull—Follow separate instructions on page 2.

1. Drill a 3mm or 1/8" pilot hole from inside the hull. If there is a rib,
strut, or other hull irregularity near the selected mounting
location, drill from the outside.

2. Using the 21mm or 7/8” drill bit, cut a hole perpendicular to the
hull from outside the boat.

3. Sand and clean the area around the hole, inside and outside, to
ensure that the marine sealant will adhere properly to the hull. If
there is any petroleum residue inside the hull, remove it with
either mild household detergent or a weak solvent (alcohol)
before sanding.

Bedding

CAUTION: Be sure all surfaces to be bedded are clean and dry.

1. Remove the hull nut (see Figure 1).

2. Apply a 2 mm (1/16") thick layer of marine sealant around the
flange of the sensor that will contact the hull and up the stem.
The sealant must extend 6mm (1/4") higher than the combined
thickness of the hull and the hull nut. This will ensure that there
is marine sealant in the threads to seal the hull and hold the hull
nut securely in place.

3. Apply a 2 mm (1/16") thick layer of marine sealant to the flange
of the hull nut that will contact the hull.

Installing

1. From outside the hull, thread the cable through the mounting
hole.

2. Push the sensor into the mounting hole using a twisting motion
to squeeze out excess marine sealant (see Figure 1).

3. From inside the hull, slide the hull nut onto the cable. Screw the
hull nut in place. Tighten it with slip-joint pliers.

Cored fiberglass hull—Do not over tighten, crushing the hull.
Wood hull—Allow for the wood to swell before tightening.

4. Remove any excess marine sealant on the outside of the hull to
ensure smooth water flow over the sensor.

Checking for Leaks

When the boat is placed in the water, immediately check around
the thru-hull sensor for leaks. Note that very small leaks may not
be readily observed. Do not to leave the boat in the water for more
than 3 hours before checking it again. If there is a small leak,
there may be considerable bilge water accumulation after 24
hours. If a leak is observed, repeat “Bedding” and “Installing”

immediately (see page 2).

Installation in a Cored Fiberglass Hull

The core (wood or foam) must be cut and sealed carefully. The
core must be protected from water seepage, and the hull must be
reinforced to prevent it from crushing under the hull nut allowing
the sensor to become loose.

CAUTION: Completely seal the hull to prevent water seepage into
the core.

1. Drill a 3mm or 1/8" pilot hole from inside the hull. If there is a rib,
strut, or other hull irregularity near the selected mounting
location, drill from the outside. (If the hole is drilled in the wrong
location, drill a second hole in a better location. Apply masking
tape to the outside of the hull over the incorrect hole and fill it
with epoxy.)

2. Using the 21mm or 7/8" drill bit, cut a hole from outside the hull
through the outer skin only (see Figure 2).

3. From inside the hull using the 30mm or 1-1/4" hole saw, cut
through the inner skin and most of the core. The core material
can be very soft. Apply only light pressure to the hole saw after
cutting through the inner skin to avoid accidentally cutting the
outer skin.

4. Remove the plug of core material so the inside of the outer skin
and the inner core of the hull is fully exposed. Clean and sand
the inner skin, core, and the outer skin around the hole.

5. Coat a hollow or solid cylinder of the correct diameter with wax
and tape it in place. Fill the gap between the cylinder and hull
with casting epoxy. After the epoxy has set, remove the
cylinder.

6. Sand and clean the area around the hole, inside and outside, to
ensure that the sealant will adhere properly to the hull. If there is
any petroleum residue inside the hull, remove it with either mild
household detergent or a weak solvent (alcohol) before sanding.

7. Proceed with “Bedding” and “Installing” (see page 2).

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