Furuno CA50-200TID-R99 Installation Instructions

INSTALLATION INSTRUCTIONS

compression
nut

Threaded-Stem Stuffing Tube

Bronze or Stainless Steel

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

17-423-01 rev. 03 05/19/10

Applications

A stuffing tube seals the hull forming a water-tight conduit for the
cable.

CAUTION: The stuffing tube must be compatible with the hull
material (see table below).

• Metal hull—Use a stainless-steel stuffing tube.

Never install a bronze stuffing tube in an aluminum hull
because electrolytic corrosion will occur.

• Fiberglass hull—The stuffing tube must be installed in solid

fiberglass, not in coring.

Hull Material

fiberglass
wood

fiberglass
wood

aluminum
steel

Stuffing Tube

Material

bronze

stainless steel

stainless steel

Cable Diameter

up to 12mm
(0.47”)

up to 12mm
(0.47”)

up to 12mm
(0.47”)

Tools & Materials

Safety goggles
Dust mask
Electric drill with 10mm (3/8") or larger chuck capacity
Drill bit: 3mm or 1/8"
Hole saw (see table above)
Sandpaper
Mild household detergent or weak solvent (such as alcohol)
File (installation in a metal hull)
Marine sealant (suitable for below waterline)
Slip-joint pliers

Hull

Hole Diameter

44mm (1-3/4") 33-511-01

44mm (1-3/4") 33-541-01

50mm (2") 33-541-01

Airmar

Part No.

plastic
washers

hull nut

rubbery
washer

Installing the Stuffing Tube

WARNING: Always wear safety goggles and a dust mask.

WARNING: Metal hull—The stainless-steel stuffing tube must be

isolated from the metal hull to prevent electrolytic corrosion.

WARNING: Metal hull—The rubbery washer must lay flat against
the hull for the stuffing tube to be firmly installed.

1. At the selected mounting location, inspect the hull interior to
ensure there is adequate clearance for the stuffing tube and any
bolts used to install the transducer. Be sure no cables, ribs, or
struts will interfere. Mark the site for the stuffing tube.

2. From inside the hull, drill a 3mm or 1/8" diameter pilot hole
perpendicular to the hull. If there is a hull irregularity near the
selected mounting location, drill from the outside.

3. Using the appropriate size hole saw, cut a hole from outside the
hull perpendicular to the hull surface (see table).

4. 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 a mild household detergent or a weak solvent (alcohol).

Metal hull—Remove all burrs with a file and sandpaper.

5. Remove the compression nut and hull nut from the stuffing tube.

6. Use marine sealant to seal the hull and hold the hull nut. Apply
a 2mm (1/16") thick layer of marine sealant around the flange of
the stuffing tube that contacts the hull and up the sidewall of the
tube (see Figure 1). The sealant must extend 6mm (1/4") higher
than the combined thickness of the hull, rubbery washer, and
the hull nut.

Metal hull—To isolate the stainless-steel stuffing tube from the

fiberglass or wood hull

marine sealant on flange

and sidewall of stuffing tube

stuffing tube

hull nut

rubbery washer

hull

Figure 1. Installing the stuffing tube

Copyright © 2006 - 2010 Airmar Tech nology Corp.

metal hull with stainless-steel stuffing tube

stuffing tube

hull nut

rubbery washer

hull

isolation

marine sealant on flange

and sidewall of stuffing tube, and

isolation bushing where it contacts the hull

bushing

metal hull, slide the isolation bushing onto the stuffing tube.
Apply additional marine sealant to the surfaces of the isolation
bushing that will contact the hull, filling any cavities in and
around the bushing.

7. From outside the hull, push the stem of the stuffing tube
through the mounting hole using a twisting motion to squeeze
out excess sealant.

8. From inside the hull, slide the rubbery washer onto the stuffing
tube.

Metal hull—The rubbery washer must contact the hull. Do not
tighten the hull nut with the rubbery washer against the isolation
bushing. The stuffing tube will not be firmly installed. If

necessary, sand the isolation bushing until the rubbery washer
rests against the hull.

9. Screw the hull nut in place. Tighten it with slip-joint pliers.

Wood hull—Allow the wood to swell. After the hull has
expanded, tighten the hull nut securely.

Installing the Transducer & Fairing

Follow the instructions that came with the transducer and fairing.
After they are installed, follow the instructions below to seal the
cable inside the stuffing tube.

Sealing the Cable in the Stuffing Tube

WARNING: To form a watertight seal inside the stuffing tube,

stagger the splits in the compliant bushings.

1. The stuffing tube kit contains two sets of plastic washers. Four
are marked 8mm (0.33") diameter and four are marked 12mm
(0.47") diameter. Choose the set of plastic washers with the
smallest diameter that will fit around your cable. (Discard the
other set; it is not needed.) Put two of the plastic-washer pieces
around the cable and press the halves together to form a closed
ring (see Figure 2).

2. The kit also contains four sets of compliant bushings with four
bushings in each set. Choose the set of compliant bushings with
the smallest diameter that will fit around your cable. (Discard the
other sets; they are not needed.) Place the four compliant
bushings around the cable above the plastic washer (see Figure

3). Arrange the bushings so that the splits are staggered—not
aligned. At the top of the stack, press the second pair of plastic
washers together to form a closed ring. Be sure the plastic

washers and compliant bushings are stacked as shown in
Figure 3.

3. To seal the cable inside the stuffing tube, push the plastic
washers and compliant bushings into the stuffing tube forming a
tight stack. Be sure the stack of plastic washers and compliant

bushings is seated securely inside the stuffing tube.

4. Screw the compression nut into the stuffing tube until it is snug.
Using slip-joint pliers, tighten the compression nut 2-1/2 turns.
This will compress the compliant bushings slightly to form a
watertight seal. Do not over-tighten.

Checking for Leaks

WARNING: Do not leave the boat in the water unchecked for

several days.

When the boat is placed in the water, immediately check around
the stuffing tube for leaks. Note that very small leaks may not be

exploded view

Figure 2. Plastic washers—12mm (0.47”) diameter shown

Copyright © 2004 Airmar Technolog y Corp.

installedexploded view

cable

compression
nut

plastic
washer

compliant
bushings

plastic
washer

NOTE: stagger the
splits in the

compliant bushings

Figure 3. Sealing the cable in the stuffing tube

Copyright © 2006  2010 Airmar Technology Corp.

readily observed. Do not leave the boat in the water unattended
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 around the stuffing tube, tighten the
compression nut another quarter turn and see if the leakage
stops. If the stuffing tube continues to leak, repeat the installation
and sealing procedures immediately.

Parts

Bronze Stuffing Tube (B165) 33-511-01
Stainless-steel Stuffing Tube (SS571) 33-541-01
Plastic Washers 20-457-01
Compliant Bushings 20-488-01

Obtain parts from your sensor 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

TECHNOLOGY CORPORATION

2

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

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