Installation Instructions

3
4. The fairing must be between 6–12mm (1/4–1/2") at its thinnest
dimension (see Figure 2).
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.
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 2). 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 appropriate drill bit, 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 a
mild household detergent or a weak solvent (alcohol) before
sanding.
Bedding
Caution : Never pull, carry, or hold the transducer by the cable as
this may sever internal connections.
1. Thread the transducer cable through the fairing (if used).
2. Apply a 2mm (1/16") thick layer of marine sealant around the
sides of the housing that will contact the fairing (or hull if no
fairing is used). Apply a 2mm (1/16") thick layer of marine
sealant to the stem of the housing, 6mm (1/4") higher than the
combined thickness of the fairing, hull, backing block, and 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. If a fairing is used, seat the transducer firmly in/against the
fairing with a pushing twisting motion (see Figures 2 or 5).
4. Apply a 2mm (1/16") thick layer of marine sealant to the surface
of the fairing that will contact the hull.
5. Apply a 2mm (1/16") thick layer of marine sealant to the surface
of the backing block that will contact the hull
Installing
1. From outside the boat, thread the cable through the mounting hole.
2. With the fairing in place and arrow facing forward toward the bow
(if used), push the stem of the transducer into the mounting hole.
(A symmetrical fairing can be oriented either way.) Squeeze out
any excess sealant.
Take care to align the assembly parallel to
the centerline of the boat
(see Figure 4).
3. From inside the hull, slide the backing block (if used) and hull
nut onto the cable. Seat the backing block against the hull.
Screw the hull nut in place and tighten it with slip-joint pliers
(see Figure 2 or 5).
Wood hul l—Allow for the wood to swell.
4. Remove excess marine sealant on the outside of the hull and
fairing to ensure smooth water flow over the transducer.
Caution : If the transducer 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.
5. Route the cable to the instrument being carefu l not to tear the
cable jacket when passing it through the bulkhead and other
parts of the boat. To reduce electrical interference, separate the
transducer cable from other electrical wiring and the engine.
Coil any excess cable and secure it in place with zip-ties to
prevent damage.
6. Refer to the instrument owner’s manual to connect the
transducer to the instrument.
marine
Figure 5. Bedding and installing (B240 with std. fairing shown)
hull nut
backing
fairing
hull
sealant
stem
BOW ➤
block
Figure 4. Transducer and fairing orientation
BOW ➤
B45 B250, B260B240B39 B46 B256
std. fairing std. fairing std. fairing std. fairing
(symmetrical)
Figure 3. Cutting the standard fairing
cutting
guide
band saw
table
deadrise
angle
arrow end
for installation
on port side
fence
B49
(symmetrical)
std. fairing
std. fairing std. fairing
SS505
std. fairing