17
-
011
-
01
rev.
02 2/03
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.
Sealcast
™
Transducer
Models: M42 and M163
Mounting Location
Acoustic Noise
Acoustic noise is always present and these sound waves can
interfere with the operation of the transducer. Ambient
(background) noise from sources such as: waves, fish, and other
vessels cannot be controlled. However, carefully selecting the
transducer’s mounting location can minimize the effect of vessel
generated noise from the propeller(s) and shaft(s), other
machinery, and other echosounders. The lower the noise level,
the higher the echosounder gain setting that can be used.
Placement
Carefully study the hull to determine the best mounting location.
• Mount the transducer away from the propeller and other
sources of vessel generated noise (see Figure 1).
•Mount where the water is smoothest with a minimum of turbulence
and bubbles. Water near the bow and keel can be quite aerated.
• Locate the transducer about 1/3 aft LWL. Generally, this
provides the best compromise between obtaining aeration-free
water away from the bow and minimizing propeller noise.
• Mount the transducer on the side of the hull where the
propeller(s) is moving downward. The upward motion of the
propeller generates pressure waves and pushes bubbles up
against the hull. By mounting on the downward side, the hull
shades the transducer from this effect (see Figure 2).
• The deeper the transducer protrudes into the water, the less
aeration.
•
Do not
mount the transducer in an area of turbulence or bubbles:
Near water intake or discharge openings
Behind strakes, fittings, or hull irregularities
Behind eroding paint (an indication of turbulence)
External Mount
Fairing and Backing Block
Nearly all vessels have some deadrise angle at the transducer’s
mounting location. If the transducer is mounted directly to the hull,
the sound beam will be tilted off the vertical at the same angle as
the deadrise. If the deadrise angle at the mounting location
exceeds 10
°
a fairing is strongly recommended (see Figure 2).
•Orients the sound beam straight down by mounting the
transducer parallel to the water’s surface
• Minimizes aerated water flowing over the transducer’s face by
mounting it deeper in the water
•Inclines the transducer so the acoustic window is shaded from
propeller noise. A 3• incline angle is recommended (see Figure 1).
Fabricating a Fairing and Backing Blocks
Measure the deadrise angle of the hull at the selected location
(see Figure 2). A fairing is usually constructed of an oily wood
such as mahogany or teak. Shape the fairing to match the outline
of the transducer housing. Orient the fairing with the blunt end
facing forward toward the bow. Cut the fairing to match the hull’s
deadrise angle and shape it as precisely as possible to the hull.
Cut a 75mm x 150mm (3" x 6") hole in the center of the fairing for
the stuffing tube and the cable service loop. Place the transducer
over the fairing and using the transducer as a guide, drill two holes
for the threaded rods (see Figure 3).
OWNER’S GUIDE & INSTALLATION INSTRUCTIONS
IMPORTANT
: Please read these 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___________Frequency________kHz
Figure 2. Deadrise angle & recommended transducer location
fairing minimizes aerated
water flowing over the
transducer’s face by
aeration, cavitation and turbulence
pressure waves
Transom View
deadrise angle
slope of hull
parallel to waterline
mounting it deeper
in the water
Figure 1. Recommended transducer location & incline angle
3˚ incline
1/3 aft
(Load Waterline Length)
LWL
angle
deadrise shape
fairing
77mm (3") 77mm (3")
backing block (2)
deadrise shape
Figure 3. Fairing and backing blocks
blunt
end
hole diameter
M42—13mm (1/2")
M163—10mm (3/8")
2
Backing blocks are mounted inside the hull to provide a level
surface for tightening the nuts that hold the threaded rods. They
are fabricated to match the interior deadrise angle. Drill a hole
through the center of each backing block (see Figure 3).
Choosing a Stuffing Tube
Installation of the transducer requires a stuffing tube. The stuffing
tube seals the hull forming a water-tight conduit for the cable.
These instructions are written specifically to install an Airmar
stuffing tube. Another stuffing tube can be used, but special care
must be taken to insure the tube will form a tight seal with the
transducer cable. Airmar can furnish stuffing tube dimensional
drawings if required.
The stuffing tube
must
be compatible with the hull material.
Aluminum hull
—Use a stainless steel stuffing tube.
Never
use a
bronze stuffing tube in an aluminum hull as electrolytic corrosion
will occur.
Installing a Threaded Stem Stuffing Tube
1.At the selected mounting location, inspect the hull interior to
ensure that there is clearance for the stuffing tube and threaded
rods.
Be sure
no cables, ribs, or struts will interfere. Mark the site
for the stuffing tube.
Warning
: Always wear safety goggles and a dust mask.
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.Outside the hull at the pilot hole, drill a 28mm or 1-1/8" diameter
hole perpendicular to the hull surface (see Figure 4).
Warning
: The fairing must be installed parallel to the keel to
ensure proper boat handling and water flow over the
transducer.
Hull Material Stuffing Tube Hole
Diameter Max. Hull
Thickness Airmar
Part No.
Fiberglass
Wood Threaded Stem
Bronze 26mm (1") 50mm (2") 33-815
Fiberglass
Wood Threaded Stem
Bronze 26mm (1") 191mm (7-1/2") 33-816
Fiberglass, Wood
Steel, Aluminum
a
a. Requires the tube to be isolated from the hull with polymer spacers.
Threaded Stem
Stainless Steel 26mm (1") 50mm (2") 33-819
Steel Welded, Steel 38mm (1-1/2") 50mm (2") 33-818
4.Locate the holes for the threaded rods by positioning the fairing
at the selected location.
•Orient the fairing with the blunt end facing forward toward the bow.
• Center the hole for the stuffing tube inside the access cavity.
•The fairing
must
be parallel to the centerline of the boat (keel).
Using the fairing as a guide, drill two holes through the hull for
the threaded rods.
M42
—13mm (1/2") diameter
M163
—10mm or 13/32" diameter
5.Sand and clean the area around the holes, inside and outside,
to ensure that the marine sealant will adhere properly. Remove
any petroleum residue before sanding.
Aluminum hull
—Remove all burrs.
6.Remove the nuts, washers, and bushing from the stuffing tube.
Use marine sealant to seal the hull and hold the flange nut
securely in place. Apply a 2mm (1/16") thick layer of marine
sealant to (see Figure 5):
• The flange that makes contact with the hull.
•The side wall of the stuffing tube, 6mm (1/4") higher than the
combined thickness of the hull, backing block, and flanged
nut (or nut and washer).
• The flange of the nut that contacts the backing block.
7. From outside, push the stem of the stuffing tube through the hull and
fasten it with the flanged nut (or nut and washer) (see Figure 4).
Fiberglass hull
—Tighten the flange nut securely.
Aluminum hull
—
Use spacers to isolate the stainless steel stuffing
tube from the hull. Be sure to apply marine sealant to the spacers.
Wood Hull
—If the boat has been out of the water for a
prolonged period,
hand-tighten
the flange nut. Wood will swell
after the boat is in the water and exert considerable pressure on
the stuffing tube hardware.
After
the hull has expanded, tighten
the nut securely.
Installing a Welded Steel Stuffing Tube
An Airmar steel stuffing tube can be installed with or without
welded conduit (see Figure 6). Some approval authorities require
that the transducer cable be encased in conduit. In such an
installation, the conduit is welded to the steel stuffing tube. In
welded conduit installations the stuffing tube must have the
compression nut tightened from outside the hull. Airmar stuffing
tubes are reversible allowing the compression nut to be mounted
outside or inside the hull.
1.At the selected mounting location, inspect the hull interior to
ensure that there is clearance for the stuffing tube and threaded
rods.
Be sure
no cables, ribs, or struts will interfere. Mark the site
for the stuffing tube on the outside of the hull.
WARNING: A Fire Watch Must Be Stationed Inside the Hull.
Figure 5. Marine sealant
on threaded stuffing tube
marine
sealant
Figure 4. Threaded stem stuffing tube installation
stuffing
flanged nut
or
nut & washer
threaded
nut (2) &
nut (2) &
rubbery
nut (2) &
plug (2)
cable
compression nut
backing
fairing
cable
transducer
hull
Bow
➣
tube
transducer
fairing
backing
service
washer (2)
washer (2)
washer (2)
washer (2)
marine
sealant
rod (2)
loop
block
block
3
service
2.At the marked location on the outside of the hull, drill or cut
(with a cutting torch) a 38mm (1-1/2") diameter hole.
Warning
: The fairing must be installed parallel to the keel to
ensure proper boat handling and water flow over the
transducer.
3.Locate the holes for the threaded rods by positioning the fairing
at the selected location (see Figure 4).
•
Be sure
to orient the fairing with the blunt end facing forward
toward the bow.
• Center the hole for the stuffing tube inside the access cavity.
•The fairing
must
be parallel to the centerline of the boat (keel).
Using the fairing as a guide, drill two holes through the hull for
the threaded rods.
M42
—13mm (1/2") diameter
M163
—10mm or 13/32" diameter
4. Grind the area around the holes, inside and outside, removing
all burrs. Clean the area around the holes to ensure that the marine
sealant will adhere properly. Remove any petroleum residue.
5.Remove the compression nut, washers, and compression
bushing from the stuffing tube. Weld the stuffing tube to the hull
(see Figure 6).
Installing the Fairing and Transducer
Welded steel stuffing tube with conduit
—It is easier to seal the
cable inside the stuffing tube before the transducer and fairing are
attached to the hull. Bolt the fairing and transducer together
following steps 1, 2, 4, and 5. Slide the washer, compression
bushing, washer, and compression nut along the transducer cable
to the stuffing tube.
Be sure
the compression bushing fits securely
weld all
transducer
cable
compression
Figure 6. Steel hull installation
metal washer,
hull
cable
conduit
fairing
stuffing tube
weld all
around
around
compression bushing
& metal washer
with conduit no conduit
marine
sealant
stuffing tube
hull
flanged nut
or
washer
compression bushing
washer
compression nut
Figure 8. Sealing the cable in a threaded stem stuffing tube
flange
nut and washer
loop
nut
compression nut
metal washer,
compression bushing
& metal washer
Figure 7. Marine sealant
hull
fairing
transducer
backing
block
4
into the machined lip of the tube. Tighten the compression nut
(see Figure 6). Follow step 3. Proceed with steps 6, 7, and 8.
Other Installations
1.Apply a 2mm (1/16") thick layer of marine sealant to the surface
of the fairing that will contact the hull (see Figures 4 and 7).
2.Apply a 2mm (1/16") thick layer of marine sealant to each
threaded rod. The marine sealant will seal the hull and hold the
nuts securely in place. Screw a nut and slide a stainless steel
washer onto each threaded rod. Position the nuts a distance
from the rod ends equal to 92mm(3-5/8") Slide the threaded
rods through the fairing.
Note: The rods will extend above and
below the fairing
.
3.Place the fairing against the hull pushing the threaded rods
through the hull. With a person stationed inside the vessel,
position the backing blocks on the rods. Secure each rod with a
stainless steel washer and nut.
Wood fairing
—Hand-tighten only. Allow the fairing to swell and
then tighten the nuts with 4 N-m (3 ft.-lb.) of force.
Caution
: Never pull, carry, or hold the transducer by its cable as
this may sever internal connections.
4.Apply a 2mm (1/16") thick layer of marine sealant to the surface of
the transducer that will contact the fairing. Thread the transducer
cable through the access cavity in the fairing and the stuffing tube
to the inside of the hull. Push the transducer onto the threaded
rods. Allow a service loop within the cavity of the fairing so there is
no tension applied to the cable (see Figures 4 and 6).
5.Mount the transducer to the fairing by sliding a rubbery washer
and stainless steel washer onto each threaded rod and securing
them with a nut (see Figure 7).
Note: The rods should extend a
minimum of 3 threads beyond the nut after it is tightened. Be sure
there is marine sealant on the exposed threads
Wood fairing
—Hand-tighten only. Allow the fairing to swell and
then tighten the nuts with 4 N-m (3 ft.-lb.) of force.
6.Plug the mounting holes to minimize turbulence on the surface
of the transducer. Cut the foam plugs to length so that each
plug will be recessed 5mm (3/16") below the surface of the
housing. Push the foam plugs into the holes. Use marine
sealant to fill each recess
flush
with the transducer’s surface.
7.Remove excess sealant on the outside of the hull and the
fairing to ensure smooth water flow over the transducer.
8.Seal the cable by sliding the washer, rubber compression bushing,
washer, and the compression nut down the transducer cable to the
stuffing tube (see Figures 6 and 8). Make sure the rubber bushing
fits securely into the machined lip of the tube. Tighten the
compression nut. Remove all excess sealant inside the hull.
In-Hull Mount
(
Fiberglass hull only)
In-hull mounting can be used in fiberglass hulls to minimize drag
when the top speed of the boat is more than 25kn (29MPH).
Although this placement results in a sound loss of 50% or more,
these powerful transducers more than compensate. Also, in-hull
mounting creates less turbulence, so the transducer’s
performance can improve above 20kn (23 MPH).
Locate the transducer where the hull is
solid
fiberglass to maximize
sound transmission.
Do not
locate over balsa wood or foam core
material as these are poor sound conductors. Consult the hull
manufacturer if you are unsure of the best location.
Never
bond the
transducer directly to the hull.
Always use a liquid-filled box
.
1.Position the transducer at the selected location and test it with
the echosounder before proceeding. Use one of the test
methods below.
•Lay the transducer against the hull and flood the area to
cover the transducer’s face.
•Grind the interior test surface smooth and wet it generously. Put
the transducer in a plastic bag, fill it with water, and close tightly.
Press the transducer’s face against the hull through the bag.
2.Construct a tank using the hull as the bottom. Design it with a
removable lid that is parallel to the waterline (see Figure 9).
3.At the selected location, grind the inside hull surface smooth
and fiberglass the tank in place.
4.On the lid, mark the location of the holes for the two threaded
rods used to mount the transducer. Locate the cable exit hole
about half way between the threaded rods. Locate a fill hole
between the transducer and the wall of the tank. Drill two holes
for the threaded rods and drill the remaining two holes.
M42
—13mm (1/2") diameter
M163
—10mm or 13/32" diameter
5.Attach the transducer to the underside of the removable lid.
Apply a 2mm (1/16") thick layer of marine sealant to the surface
of the transducer that will make contact with the lid. Thread the
cable through the center hole in the lid. Apply a 2mm (1/16") thick
layer of marine sealant to each threaded rod end. Secure each
rod with a nut. The rods should extend a minimum of 3 threads
beyond the nut. Slide a stainless steel washer and rubbery
washer onto each rod. Push the threaded rods through the
transducer and lid. Apply a 2mm (1/16") thick layer of marine
sealant to the rods near the lid. Secure the assembly in place
with stainless steel washers and nuts. Tighten the nuts with a
AIRMAR
TECHNOLOGY CORPORATION
35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA
■
www.airmar.com
Figure 9. In-hull installation (fiberglass hull only)
fiberglass
tank
(G10 fiberglass,
nut (2) &
rubbery
pipe plug
cable
transducer
LEXAN®, or
stainless steel)
(marine
removable lid threaded rod (2) with fill hole with
in place
plywood)
washer (2)
washer (2)
screw (4) & washer (4)
(stainless steel)
washer (2) & nut (2)
(supplied)
(supplied)
(supplied)
mineral oil
marine sealant on
transducer, around cable,
and perimeter of tank
mineral oil
grind surface smooth
/
