INSTALLATION INSTRUCTIONSOWNER’S GUIDE &
Thru-Hull
TRIDUCER
Models: B66V, B66VL, B744V, B744VL
IMPORTANT: Please read the instructions completely
before proceeding with the installation. These
instructions supersede any other instructions in your
instrument manual if they differ.
WARNING: B744V and B744VL
17-118-03 rev. 04 06/27/11
These models must be installed with a fairing (Standard or
High-Performance). If the multisensor is installed without a
fairing, there is insufficient surface area to seal the multisensor to the hull. Water may leak into the hull causing
damage to the boat or possibly sinking.
WARNING: B744V, B744VL
with a High-Performance Fairing
These models must be installed following the supplemental
instructions that came with the
High-Performance Fairing requires an anti-rotation bolt. Failure
to install the anti-rotation bolt may result in the fairing rotating
while the boat is underway. The effect may be violent
movement and loss of steering. This could result in serious
injury or death to passengers and/or damage to the boat or
other property.
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.
Applications
• Bronze housings recommended for fiberglass or wood hulls.
Caution: Never install a bronze housing in a metal hull because
electrolytic corrosion will occur.
• Caution: Never install a metal housing in a vessel with a
positive ground system.
Pretest
Connect the multisensor to the instrument and spin the
paddlewheel. Check for a speed reading (and the approximate air
temperature if applicable). If there is no reading or it is inaccurate,
return the instrument to the place of purchase.
Identify Your Model
The model name is printed on the cable tag.
®
Multisensor with Strap
High-Performance Fairing. A
Record the information found on the cable tag for future reference.
Part No._________________Date___________Frequency________kH
B744V
B744V
Standard Fairing
Tools and Materials
Fairing (mandatory for B744V, B744VL)
Safety goggles
Dust mask
Digital level (installation with fairing)
Band saw (installation with fairing)
Rasp or power tool (installation with fairing)
Electric drill
Drill bit: 3mm or 1/8"
Hole saw: 51mm or 2"
Sandpaper
Mild household detergent or weak solvent (alcohol)
Marine sealant (suitable for below waterline)
Slip-joint pliers
Zip-ties
Water-based antifouling paint (mandatory in salt water)
Installation in a cored fiberglass hull (see page 4):
Hole saw for hull interior: 60 mm or 2-3/8"
Cylinder, wax, tape, and casting epoxy
Mounting Location
Acoustic Noise
Acoustic noise is always present and these sound waves can
interfere with the operation of the transducer. Background noise
from sources such as: waves, fish, and other vessels cannot be
controlled. However, carefully selecting the multisensor’s
mounting location can minimize the affect 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
Choose a location where:
• The water flowing across the hull is smoothest with a minimum
of turbulence and bubbles (especially at high speeds).
• The multisensor will be continuously immersed in water.
• There is a minimum deadrise angle.
• The transducer beam will be unobstructed by the keel or
propeller shaft(s).
• There is adequate headroom inside the vessel for the height of
the housing, tightening the nuts, and removing the valve
assembly and insert.
Caution: Do not mount the multisensor:
Near water intake or discharge openings
Behind strakes, fittings, or hull irregularities
Behind eroding paint (an indication of turbulence)
AIRMAR
®
1/3 aft
LWL
(Load Waterline Length)
outboard and I/O
step-hull
Figure 1.
pressure waves
150– 300 mm
(6– 12")
displacement hull
planing hulls
fin keel sailboat
full keel sailboat
inboard
Best location for the multisensor
Boat Types (see Figure 1)
• Displacement hull powerboat—Locate 1/3 aft LWL and
150–300mm (6–12") off the centerline on the side of the
hull where the propeller is moving downward.
• Planing hull powerboat—Mount well aft near the centerline
and well inboard of the first set of lifting strakes to insure that
it is in contact with the water at high speeds. Mount on the
side of the hull where the propeller is moving downward.
Outboard and I/O—Mount forward and to the side of the
engine(s).
Inboard—Mount well ahead of the propeller(s) and shaft(s).
Step-hull—Mount just ahead of the first step.
Boats capable of speeds above 25kn (29MPH)—Review
multisensor location and operating results of similar boats
before proceeding.
• Fin keel sailboats—Mount to the side of the centerline
and forward of the fin keel 300–600mm (1 – 2').
• Full keel sailboats—Locate amidships and away from the
keel at the point of minimum deadrise angle.
Headroom
Allow adequate headroom inside the vessel for the height of
the housing, tightening the nuts and removing the insert.
Model
B744V — 255mm (10")
B744VL — 381mm (15")
B66V 270mm (10
B66VL 394mm (15
2
Min. no fairing Min. with fairing
5
⁄8") 255mm (10")
1
⁄2") 381mm (15")
About Fairings
Nearly all vessels have some deadrise angle at the mounting location. If
the multisensor is mounted directly to the hull, the sound beam will be
tilted off the vertical at the same angle as the deadrise. A fairing is
strongly recommended if the deadrise angle exceeds 10°(see Figure 2).
• Increases the sealing surface around the drilled hole to prevent
water from leaking into the hull.
• Orients the sound beam straight down by mounting the multisensor
parallel to the water surface
• Minimizes aerated water flowing over the transducer’s face by
mounting it deeper in the water
• High-Performance Fairing has a long streamlined shape for
excellent performance above 15 knots (see Replacement Parts on
page 6).
Airmar Polymer Fairing
Made of a high impact polymer with an integrated cutting guide, an
Airmar fairing is safer and easier to cut with a band saw and shape
with hand tools than custom fairings. It can be shaped to
accommodate a deadrise angle of up to 25°. (For fairing part numbers,
see “Replacement Parts” on page 6.)
A backing block is used inside the hull to provide a level surface for the
hull nut to seat against (see Figure 2). It is fabricated matching the
interior deadrise angle of the boat. After cutting an Airmar fairing, use
the remaining section with the cutting guide as the backing block.
Installation (for Standard Fairing Only)
WARNING: B744V, B744VL with a High-Performance Fairing must
be installed following the supplemental instructions that came with
your High-Performance Fairing. The High-Performance Fairing
requires an anti-rotation bolt. Failure to install the anti-rotation bolt may
result in the fairing rotating while the boat is underway. The effect may
be violent movement and loss of steering. This could result in serious
injury or death to passengers and/or damage to the boat or other
property.
WARNING: B744V and B744VL
(Standard or High-Performance). If it is installed without a
fairing, there is insufficient surface area to seal the sensor to
the hull. Water may leak into the hull causing damage to the
boat or possibly sinking.
CORED FIBERGLASS HULL—Follow separate instructions on page 4.
Hole Drilling
Warning: Always wear safety goggles and a dust mask.
1. Drill a 3mm or 1/8" pilot hole perpendicular to the waterline from
inside the hull (see Figure 3). If there is a rib, strut, or other hull
irregularity near the selected mounting location, drill from the outside.
If the pilot 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 51mm or 2" hole saw, cut a hole from outside the hull. Be
sure to hold the drill plumb, so the hole will be perpendicular to the
water surface.
3. 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.
must be installed with a fairing
Cutting the Standard Fairing
1. Measure the deadrise angle of the hull at the selected location
using a digital level (see Figure 2).
2. Tilt the band saw table to the measured angle and secure the
cutting fence (see Figure 4).
3. Place the fairing on the table, so the cutting guide rests against
the fence. The arrow will point toward you for installation on the
port side and away from you for installation on the starboard
side of the boat (see Figures 4 and 5).
Note: The ARROW always points forward toward the bow. Be
sure to orient the fairing on the band saw so the angle cut
matches the intended side of the hull and not the mirror image.
4. Adjust the cutting fence. The fairing must be between 6 – 12 mm
(1/4–1/2") at its thinnest dimension (see Figure 2).
AIRMAR
backing
block
hull
fairing thickness
at thinnest point
6– 12 mm (1/4–1/2")
slope of hull
parallel to
waterline
fairing
multisensor
deadrise
angle
Figure 2. Deadrise angle & fairing thickness (B744V shown)
®
Warning: Always wear safety goggles and a dust mask.
5. Recheck steps 1 through 4. Then cut the fairing.
6. Shape the fairing to the hull as precisely as possible with a rasp
or power tool.
7. Use the remaining section of the fairing for the backing block.
Bedding the Housing
1. Apply a 2mm (1/16") thick layer of marine sealant over the surface
of the multisensor housing that will contact the fairing (or hull if no
fairing is used) and up the stem, 6mm (1/4") higher than the
combined thickness of the fairing, hull, backing block, and hull nut
(see Figure 3). This will ensure there is marine sealant in the
threads to seal the hull and hold the hull nut securely in place.
2. Slide the fairing (if used) onto the stem and mate the button with
the recess in the housing (see Figure 5).
3. Apply a 2mm (1/16") thick layer of marine sealant to the side of
the fairing (if used) that will contact the hull (see Figure 3).
4. Apply a 2mm (1/16") thick layer of marine sealant to the side of
the backing block (if used) that will contact the hull.
Installing the Housing
Caution: Never strike the multisensor.
cap nut
hull nut
backing
block
hull
marine sealant
Figure 3. Drilling and bedding (B744V shown)
band saw
table
deadrise
angle
AIRMAR
stem
fairing
cutting
guide
®
1. From outside the hull, push the stem of the multisensor housing
(with the fairing in place if used) through the mounting hole using
a twisting motion to squeeze out excess sealant (see Figure 3).
If an Airmar fairing is used, be sure the button on the fairing is
mated with the recess in the multisensor, the arrow on the fairing
is pointing forward. Take care to align the assembly parallel
to the centerline of the boat (see Figure 5).
2. From inside the hull, slide the backing block (if used), hull nut,
and cap nut along the cable. Slide the backing block onto the
stem and seat it firmly against the hull. Screw the hull nut in
place. Tighten it with slip-joint pliers (see Figure 3).
Wood hull—Allow for the wood to swell.
Caution: Be careful to avoid cross threading the cap nut.
3. Being sure the valve assembly is seated firmly in the housing,
carefully screw the cap nut in place. HAND-TIGHTEN only.
Do not over tighten.
4. Remove any excess sealant on the outside of the fairing and
hull to ensure smooth water flow over the multisensor.
end with arrow
for installation
on port side
Figure 4. Cutting the fairing
AIRMAR
®
BOW ►
Figure 5. Airmar urethane fairing (B744V shown)
recess in
housing
fence
AIRMAR
cutting
guide
button
®
3
top view of
paddlewheel
insert
BOW ►
paddlewheel
insert
housing and
valve assembly
paddlewheel
insert detail
pull ring
O-rings
shaft
notches
blanking
plug
cable
key (2)
valve
assembly
cap nut
housing
flat side of
paddlewheel
blade faces
direction of
arrow on top
of insert
(toward bow)
AIRMAR
®
Warning: Always attach the safety wire to prevent the insert
from backing out in the unlikely event that the cap nut fails or is
screwed on incorrectly.
5. Attach the safety wire. Wrap one end of the safety wire tightly
around the stem of the housing and twist it together with the
long end. Lead the wire straight up and through one eye in the
cap nut, then through the safety ring. Loop the wire through the
pull ring and twist it securely to itself.
Caution: If the multisensor came with a connector, do not
remove it to ease cable routing. If the cable must be cut and
spliced, use Airmar’s splash-proof Junction Box 33-035 and
follow the instructions provided. Cutting the cable or removing
the connector, except when using Airmar’s junction box, will
void the warranty.
6. 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. To reduce electrical interference, separate the
multisensor cable from other electrical wiring and the engine.
Coil any excess cable and secure it in place using zip-ties to
prevent damage.
7. Refer to the echosounder owner’s manual to connect the
multisensor to the instrument.
Preparing 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 housing to become loose.
Warning: Always wear safety goggles and a dust mask.
1. Drill a 3mm or 1/8" pilot hole perpendicular to the waterline from
inside the hull (see Figure 8). 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.
cable
AIRMAR
®
Figure 6. Paddlewheel insert, blanking plug,
and valve assembly (B744V shown)
Installing the Paddlewheel Insert
WARNING: The O-rings must be intact and well lubricated to
make a watertight seal.
1. Attach one pull ring to the paddlewheel insert. Attach the second
pull ring to the blanking plug (see Figure 6).
2. After the sealant cures, inspect the O-rings on the paddlewheel
insert and lubricate them with the silicone lubricant supplied.
3. With the arrow on the top of the paddlewheel insert pointing
forward toward the bow, slide it into the housing with a twisting
motion until it is fully seated. (The insert fits one way only.) Take
care not to rotate the outer housing and disturb the sealant.
4. Wrap the safety strap around the cable and pass the holed end
through the slit in the opposite end. Attach the safety ring to the
hole midway in the strap. Insert the retaining pin in the hole in
the end of the strap. Slide the free end of the retaining pin
through the valve and insert. Secure the retaining pin with the
safety ring (see Figure 7).
4
cap nut
stem
hull nut
backing
block
safety strap
pull ring
retaining pin
safety ring
safety wire
hull
fairing
multisensor
Figure 7. Installation (B744V shown)
AIRMAR
®
pour in
casting
epoxy
Dimension equal to
the thickness of the
hull’s outer skin to
ensure adequate
clearance
inner skin
core
Paint the following surfaces (see Figure 9):
• Exposed areas of the housing including the acoustic window
• Bore of the housing up 30mm (1-1/4")
• Outside wall below lower O-ring of paddlewheel insert
• Paddlewheel cavity
• Paddlewheel
• Blanking plug below lower O-ring including exposed end
hull
outer skin
solid or hollow
cylinder
Figure 8. Preparing a cored fiberglass hull
2. Using the 51mm or 2" hole saw, cut a hole from outside the hull
through the outer skin only. Be sure to hold the drill plumb, so
the hole will be perpendicular to the water surface.
3. The optimal interior hole diameter is affected by the hull’s
thickness and deadrise angle. It must be large enough in
diameter to allow the core to be completely sealed.Using the
60mm or 2-3/8" hole saw, cut through the inner skin and most
of the core from inside the hull keeping the drill perpendicular to
the hull. 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 inner core of the hull is fully exposed. Sand and clean the
inner skin, core, and the outer skin around the hole.
Caution: Completely seal the hull to prevent water seepage
into the core.
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 such as alcohol
before sanding.
7. Proceed with “Bedding the Housing” and “Installing the Housing”.
Check for Leaks
Operation, Maintenance, Repair, & Parts
How the Valve Works
The multisensor incorporates a self-closing valve which minimizes
the flow of water into the vessel when the paddlewheel insert is
removed. The curved flap valve in the valve assembly is activated
by both a spring and water pressure. The flap valve is pushed
upward to block the opening, so there is no plume of water into
the boat (see Figure 6).
WARNING: THE VALVE IS NOT A WATERTIGHT SEAL.
Always use the paddlewheel insert or blanking plug secured with
the retaining pin, safety ring, and safety wire for a watertight seal.
Blanking Plug
To protect the paddlewheel, use the blanking plug when:
• The boat will be moored in salt water for more than a week.
• The boat will be removed from the water.
• Aquatic growth buildup on the paddlewheel is suspected due to
inaccurate readings from the instrument.
WARNING: The O-rings must be intact and well lubricated for
a watertight seal.
1. Inspect the O-rings on the blanking plug and lubricate them with
silicone lubricant or petroleum jelly (Vaseline®) (see Figure 6).
2. Remove the safety wire from the pull ring and cap nut. Remove
the safety ring and pull out the retaining pin (see Figure 7).
Do not remove the cap nut.
3. Grasp the pull ring and remove the paddlewheel insert with a
slow pulling motion.
Note: In the unlikely event that the paddlewheel insert cannot
be removed, see “Servicing the Valve Assembly”.
4. With the arrow on the top pointing forward, slide the blanking
plug into the housing until it is fully seated. Secure it with the
retaining pin, safety ring, and safety wire (see Figure 6).
housing
AIRMAR
®
Warning: Never install a thru-hull multisensor and leave the boat
in the water unchecked for several days.
When the boat is placed in the water, immediately check the
thru-hull multisensor for leaks. Note that very small leaks may not
be readily observed. It is best 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 the Housing” and
“Installing the Housing” immediately.
Antifouling Paint
Marine growth can accumulate rapidly on the multisensor’s
surface reducing performance within weeks. Surfaces exposed to
salt water must be coated with antifouling paint. Use water-based
antifouling paint only. Never use ketone-based paint since
ketones can attack many plastics possibly damaging the
transducer. Reapply paint every 6 months or at the beginning of
each boating season.
Paint exposed housing
and bore up 30 mm (1-1/4")
detail
including exposed end, paddlewheel cavity and paddlewheel
Paint outside wall below the lower O-ring
Figure 9. Antifouling paint (B744V shown)
paddlewheel
insert
lower
O-ring
5
Cleaning the Multisensor
Aquatic growth can accumulate rapidly on the multisensor’s
surface, reducing it’s performance in weeks. Clean the surface
with mild household detergent. If fouling is severe, use a stiff
brush or putty knife to remove the growth being careful to avoid
making scratches.The paddlewheel can be removed by pushing
out the shaft using a spare shaft or a 4D finish nail with a flattened
point. Wet sand the paddlewheel with fine grade wet / dry paper.
Servicing the Paddlewheel Insert
The water lubricated paddlewheel bearings have a life of up to 5
years on low-speed boats [less than 10kn (11MPH)] and 1 year
on high-speed vessels. Paddlewheels can fracture and shafts can
bend due to impact with water borne objects and mishandling in
boat yards. O-rings must be free of abrasions and cuts to ensure
a watertight seal. Order a replacement Paddlewheel Kit #33-113.
1. Using the new paddlewheel shaft, push the old shaft out about
6mm (1/4"). With pliers, remove the old shaft (see Figure 6).
2. Place the new paddlewheel in the cavity with the flat side of the
blade facing the direction of the arrow on the top of the insert.
3. Tap in the new shaft until the ends are flush with the insert.
4. Install two O-rings in the lower groves near the paddlewheel.
Do not place them near the pull ring.
5. The remaining two O-rings are placed in a similar position near
the bottom on the blanking plug.
Warning: If a new valve assembly is required and not
immediately available, the valve sleeve must be reinstalled in
the multisensor housing for a watertight seal. Remove the flap
valve, spring pin, and spring from the sleeve.
4. Clean, repair, or replace the valve assembly so that the flap valve
moves freely and seats against the sleeve (see Figure 10).
WARNING: The O-rings must be intact and well lubricated
for a watertight seal.
5. To reinstall the valve assembly, inspect the O-rings on the
paddlewheel insert and lubricate them with silicone lubricant or
petroleum jelly (Vaseline®) (see Figure 6).
6. Slide the paddlewheel insert into the valve assembly. Seat it in
place with a twisting motion until the keys fit into the notches.
Secure the paddlewheel insert with the retaining pin and safety
ring (see Figure 7).
Caution: Be careful to avoid cross threading the cap nut.
7. Remove the safety wire from the multisensor. With the valve
assembly ready in one hand, remove the blanking plug. Slide
the assembly into the multisensor housing with the arrow on the
top pointing forward. Be sure the cable fits into the cable
channel and the key in the housing fits into the notch in the
sleeve (see Figure 10). (A pushing twisting motion will locate
the key.) Screw the cap nut in place and hand-tighten only.
Do not over tighten.
Servicing the Valve Assembly
Should the valve fail, remove it for servicing. Order a replacement
Paddlewheel and Valve Kit #33-218.
WARNING: The blanking plug cannot be secured without the
valve assembly. After removing the valve assembly, temporarily
insert the blanking plug, but do not leave the boat in the water
unattended.THIS IS NOT A WATERTIGHT OR SECURE SEAL!
Warning: O-rings must be intact and well lubricated to make
a watertight seal.
1. Inspect the O-rings on the blanking plug and lubricate them with
silicone lubricant or petroleum jelly (Vaseline®) (see Figure 6).
2. Remove the safety wire and unscrew the cap nut. With the
blanking plug ready in one hand, remove the paddlewheel
insert and valve assembly as one unit by grasping the pull ring
and pulling upward (see Figure 7). Rapidly replace the valve
assembly with the blanking plug to minimize the flow of water
into the boat. TEMPORARILY secure it with the safety wire.
3. Separate the
paddlewheel insert
from the valve
assembly by removing
the safety ring and the
retaining pin. Grasp
the pull ring and pull
slowly upward.
notch
cable
channel
flap
valve
Figure 10. Valve assembly
AIRMAR
sleeve
spring
pin
spring
®
Warning: Always attach the safety wire to prevent the insert
from backing out in the unlikely event that the cap nut fails or is
screwed on incorrectly.
8. Reattach the safety wire (see Figure 7).
Winterizing
After the boat has been hauled for winter storage, remove the
blanking plug to let the water drain away before re-inserting it.
This will prevent any water from freezing around the blanking plug
and possibly cracking it.
Replacement Parts
Lost, broken, and worn parts should be replaced immediately and
can be obtained through your marine dealer or instrument
manufacturer.
Model Cap Nut Hull Nut
B744V 04-234-1 02-030 04-469-01 33-476-01 33-385-01 20-752-1
B744VL 04-234-1 02-030 04-469-01 33-476-01 33-483-01 20-752-3
B66V 04-234-1 02-030 33-029 — 33-385-01 20-752-1
B66VL 04-234-1 02-030 33-029 — 33-483-01 20-752-3
Standard
Fairing
HighPerformance
Fairing
Blanking
Plug
Insert
Part Part No.
Paddlewheel Kit 33-113
Paddlewheel & Valve Kit 33-218
Replacing the Multisensor
The information needed to order a replacement Airmar multisensor
is printed on the cable tag. Do not remove this tag. When ordering,
specify the part number, date, and frequency in kHz.
®
AIRMAR
6
TECHNOLOGY CORPORATION
35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA
Copyright 2001 - 2011. All rights reserved.
www.airmar.com
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