Airmar B122—Long-Stem - Manual (Page 3)

3
Installation with Fairing : Suitable for B122, DST800L
Hole Drilling: Sensor
Cored fiberglass hull—Follow separate instructions on page 7.
1. Drill a 3mm or 1/8" pilot hole perpendicular to the waterline from
inside the hull. If there is a rib, strut, or other hull irregularity near
the selected mounting location, drill from the outside.
2. Using the 51mm or 2" hole saw, cut a hole from outside the
boat (see Figure 3). Be sure to hold the drill plumb, so the hole
will be perpendicular to the water surface.
Cutting the 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.
CAUTION: The housing must be flush with the fairing for smooth
water flow under the sensor.
1. Measure the deadrise angle of the hull at the selected mounting
location using an angle finder (see Figure 3). Check to be sure
the angle does not exceed the 35° maximum allowed.
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 (see Figures 4 and 5). The end with the triangular
recess will be pointing toward you for installation on the
starboard side of the boat or pointing 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 13mm (1/2") at its thinnest dimension (see Figure 3).
Cutting the fairing at an angle greater than 35° will cut into the
sensor and/or bolt pocket, thus weakening the fairing.
5. Recheck steps 1 through 4. Then cut the fairing.
6. When the boat is underway, especially at high speeds, water
will enter gaps and push against the fairing with considerable
force. 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.
7. Check to be sure the housing is flush with the fairing. If it is
recessed more that 0.5mm (1/64") inside the fairing, you may
shim the housing or carefully file/sand the fairing.
8. Use the remaining section of the fairing with the cutting guide
for the backing block.
Figure 4. Cutting the fairing
deadrise
angle
cutting
guide
cutting
band saw
table
end with arrow
and triangular recess
for installation on
fence
triangular
recess for
anti-rotation bolt
cutting
guide
Figure 5. High-performance fairing
WARNING
Installation of the anti-rotation bolt is mandatory in a High-Performance Fairing!
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.
Copyright © 2006 Airmar Technology Corp. Copyright © 2006 Airmar Technology Corp.
starboard side of hull
deadrise
angle
slope of hull
parallel to
water surface
Figure 3. Measuring the deadrise angle
backing block
min. fairing
thickness
13mm (1/2")
aft view
fairing
hull
Copyright © 2006 - 2011 Airmar Technology Corp.
NOTE: fairing must
be flush with housing
sensor
transducer face
and fairing thickness (B122 shown)