Furuno DFF-3D - Mounting Location

APPENDIX 3 INSTALLATION OF TRANSDUCER B54
AP-5
2
Mounting Location
CAUTION: Do not mount in line with or near water intake or
discharge openings or behind strakes, struts, fittings, or hull
irregularities.
• The water flowing under the hull must be smooth with a
minimum of bubbles and turbulence (especially at high speeds).
• The transducer’s face must be continuously immersed in water.
• The transducer beam must be unobstructed by the keel or
propeller shaft(s).
• Choose a location away from interference caused by power and
radiation sources such as: the propeller(s) and shaft(s), other
machinery, other echosounders, and other cables. The lower
the noise level, the higher the echosounder gain setting that
can be used.
• Choose a location with a minimum deadrise angle.
• Choose an accessible spot inside the vessel with adequate
headroom for the height of the stem and tightening the nut.
Boat Types
(see Figure 1)
• Displacement hull powerboat—Locate 1/3 of the way back
along the LWL and 150–300mm (6–12") off the centerline. The
starboard side of the hull where the propeller blades are moving
downward is preferred.
• 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. The starboard side of the
hull where the propeller blades are moving downward is preferred.
Outboard and I/O —Mount just forward and to the side of the
engine(s).
Inboard—Mount well ahead of the propeller(s) and shaft(s).
Stepped hull—Mount just ahead of the first step.
Boat capable of speeds above 25kn (29MPH)—Review
transducer location and operating results of similar boats before
proceeding.
Installation
Cored Fiberglass Hull —Follow separate instructions on page 4.
H
ole Drilling: Transducer
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.
2. Using a
51mm or 2" drill bit or 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.
Cutting the High-Performance Fairing
CAUTION: The end of the fairing with the arrows/triangular
recess always points forward toward the bow when installed. 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.
1. Measure the deadrise angle of the hull at the selected mounting
location using an angle finder (see Figure 2). Check to be sure
the angle does not exceed 24°.
2. Tilt the band saw table to the measured angle and secure the
cutting fence (see Figure 3). Do not exceed 24°.
3. Place the fairing on the table, so the cutting guide rests against
the fence. The end with the arrows and triangular recess will be
pointing toward you for installation on the starboard side of the
boat or away from you for installation on the port side.
4. Adjust the cutting fence, so the fairing will be cut in about two equal
parts. The section that will become the fairing must be a minimum
of 45mm (1-3/4") at its thinest dimension (see Figure 2).
5. Recheck steps 1 through 4. Then cut the fairing.
6. When the boat is underway, especially at high speeds, water
will enter any gaps and push against the fairing with
considerable force, possibly rotating it. Shape the fairing to the
hull as precisely as possible with a rasp or power tool. If there is
a gap of more than 3mm (1/8"), replace the fairing.
Figure 1.
pressure waves
1/3 aft
displacement hull
(6-12")
150-300mm
LWL
Best location for the transducer
(Load Waterline Length)
stepped hull
outboard and I/O
planing hulls
Copyright © 2005 Airmar Technology Corp.
inboard
Figure 3. Cutting the High-Performance Fairing
deadrise
angle
cutting
guide
band saw
table
triangular recess
for installation
on starboard side
fence
Copyright © 2005 - 2010 Airmar Technology Corp.
of the hull
end with arrows and
deadrise
angle
slope of hull
parallel to
water surface
Figure 2. Deadrise angle and fairing thickness
backing block
min. fairing
thickness
45mm (1-3/4")
aft view
fairing
hull
Copyright © 2016 Airmar Technology Corp.
NOTE: fairing must
be flush with housing
stem
transducer face
hull nut
transducer