Installation Instructions
2
About Fairings
Nearly all vessels have some deadrise angle at the 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. A fairing is strongly recommended if the deadrise angle
exceeds 10
°
(see Figure 2).
• Orients the sound beam straight down by mounting the
transducer parallel to the water surface
• Minimizes aerated water flowing over the transducer’s face by
mounting it deeper in the water
Airmar Urethane Fairing
Made of a high impact urethane 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 4.)
Backing Block
A backing block is mounted 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 as the backing
block.
Hull Thickness
(measured perpendicular to the waterline)
Minimum Maximum Maximum
Model
no fairing no fairing with fairing
B39, B49 19mm (
3
⁄
4
") 98mm (3
7
⁄
8
") 50mm (2")
B45 6mm (
1
⁄
4
") 92mm (2
5
⁄
8
") 50mm (2")
B46 19mm (
3
⁄
4
") 88mm (3
1
⁄
2
") 40mm (1
5
⁄
8
")
B240 32 mm (1
1
⁄
4
") 152mm (6") 83mm (3
1
⁄
4
")
B250, B256, B26019mm (
3
⁄
4
") 114mm (4
1
⁄
2
") 45mm (1
3
⁄
4
")
SS505 6mm (
1
⁄
4
") 104mm (4
1
⁄
8
") 56mm (2
1
⁄
4
")
Installation
(no fairing or standard fairing only)
WARNING
:
High-speed fairing
must be installed following the
Installation Instruction Supplement that comes with the fairing.
The high-speed 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.
Metal hull
—The SS505 must be isolated from a metal hull. For
your safety you must follow the Installation Instruction Supplement
provided with the fairing.
Cored fiberglass hull
—Follow separate instructions on page 4.
No fairing
—If you are installing a transducer without a fairing,
disregard all references to a fairing.
Cutting the Fairing
High speed fairing
—For your safety it is mandatory to follow the
Installation Instruction Supplement that comes with the fairing.
1. Measure the deadrise angle of the hull at the selected location
using a digital level, or bubble level and protractor (see Figure 2)
2. Tilt the band saw table to the measured angle and secure the
cutting fence (see Figure 3).
3. Place the fairing on the table so the cutting guide rests against
the fence. The arrow will be pointing toward you for installation
on the port side and away from you for installation on the
starboard side of the boat (see Figures 3 and 4).
Notice
: The ARROW always points forward toward the bow.
(A symmetrical fairing can be oriented either way.) 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.
inboard
Figure 1.
pressure waves
1/3 aft
full keel sailboat
displacement hull
(6-12")
fin keel sailboat
150-300mm
LWL
Best location for the transducer
(Load Waterline Length)
step-hull
outboard and I/O
planning hulls
hull nut
marine
backing block
Figure 2. Bedding and installing (B45 with std. fairing shown)
6–12mm (1/4–1/2")
standard fairing
fairing thickness
hull
deadrise
angle
sealant
stem
Aft View
slope of hull
parallel to
waterline
cable