Furuno DFF-3D Operator's Manual page 62

APPENDIX 3 INSTALLATION OF TRANSDUCER B54
hull nut
backing
block
marine sealant on following (shown in red):
- transducer, extending above hull nut 1/4" (NOT surface that will touch water)
- fairing that contacts hull
- backing block that contacts hull
- hull nut that contacts backing block
- anti-rotation bolt including bolt head, extending above nut 1/4"
- anti-rotation washer that contacts backing block
- yellow triangular plug: fill hollow half way (NOT curved surface that will touch water)
7. Check to be sure the transducer is flush with the fairing. If it is
recessed more than 0.5mm (1/64") inside the fairing, you may
shim the transducer or carefully file/sand the fairing.
8. The remaining section of the fairing with the cutting guide will
be used as the backing block inside the hull. It will provide a
level surface for tightening the nuts.
Hole Drilling: Anti-rotation Bolt
To locate and drill the hole for the anti-rotation bolt, use the fairing
as a guide. This will ensure that the hole is perpendicular to the
waterline and not drilled at the angle of the hull.
1. Dry fit the transducer in the fairing. Thread the cable through the
large hole in the fairing and through the mounting hole in the hull.
Seat the transducer firmly within the recess in the fairing (see
Figure 4). Be sure the arrow on the transducer points toward the
triangular recess in the fairing.
2. Slide the transducer with the fairing in place into the mounting
hole. Using the bolt hole in the fairing as your guide, drill a 3mm
(1/8") pilot hole through the hull for the anti-rotation bolt.
3. Using the drill bit or hole saw, hold the fairing in
11mm or 7/16"
place and drill a hole for the anti-rotation bolt.
4. Remove the assembly and cable from the mounting hole.
5. Sand and clean the area around both holes, 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.
Bedding the Transducer
CAUTION: Be sure the surfaces to be bedded are clean and dry.
1. Remove the transducer from the fairing.
2. Apply a 2mm (1/16") thick layer of marine sealant to the surface
of the transducer that will contact the fairing and up the stem
(see Figure 4 areas in red). The sealant must extend 6mm
(1/4") higher than the combined thickness of the fairing, hull,
backing block, and hull nut. This will ensure there is marine
sealant in the threads to seal the hull and hold the hull nut
securely in place.
AP-6
stem
transducer
Figure 4. Bedding and installing
Copyright © 2016 Airmar Technology Corp.
anti-rotation
bolt
nut &
washer
High-
Performance
Fairing
triangular plug
with curved
surface facing
outward
3. Apply a 2mm (1/16") thick layer of marine sealant to the
following surfaces:
• Fairing that will contact the hull
• Backing block that will contact the inside of the hull
• Hull nut that will contact the backing block
4. Thread the transducer cable through the fairing and seat the
transducer firmly within the recess. Be sure the arrow on the
transducer points toward the triangular recess in the fairing.
Installing the Transducer
1. From outside the hull, thread the transducer cable through the
mounting hole. Push the stem of the transducer (with the fairing
in place) into the mounting hole using a twisting motion to
squeeze out excess sealant (see Figure 4). Be sure the arrow
on the transducer points forward toward the bow.
NOTE: The transducer must be FLUSH with the fairing. If it is
recessed more than 0.5mm (1/64") inside the fairing, you may
shim the transducer or carefully file/sand the fairing.
2. From inside the hull, slide the backing block onto the transducer
cable and stem, seating the backing block firmly against the
hull. Screw the hull nut in place, but do not tighten it at this time.
Bedding & Installing the Anti-rotation Bolt
CAUTION: Be sure the surfaces to be bedded are clean and dry.
1. Apply a 2mm (1/16") thick layer of marine sealant to the anti-
rotation bolt including the flange (see Figure 4). The sealant
must be 6mm (1/4") higher than the combined thickness of the
fairing, hull, backing block, washer, and nut. This will ensure that
there is marine sealant on the threads to seal the hull and hold
the nut securely in place.
2. Apply a 2mm (1/16") thick layer of marine sealant to the side of
the washer that will contact the backing block.
3. Push the anti-rotation bolt through the fairing and the hull.
4. From inside the hull, screw the washer (sealant side down) and
the nut onto the anti-rotation bolt.
5. Use slip-joint pliers to tighten the hull nut. Then tighten the nut
on the anti-rotation bolt. Do not over-tighten, crushing the
fairing or hull.
Cored fiberglass hull —Do not over tighten, crushing the hull.
Wood hull —Allow for the wood to swell before tightening the nut.
►
BOW
NOTE: Be sure
the arrow on the
transducer
points forward
toward the bow.
hull
3