Airmar CS4500-650—Ultrasonic Speed - Manual (Page 3)

3
Bedding
CAUTION: Be sure the surfaces to be bedded are clean and dry.
Apply a 2mm (1/16") thick layer of sealant around the flange of
the housing that contacts the hull and up the sidewall of the
housing. The sealant must extend 6mm (1/4") higher than the
combined thickness of the hull, washer(s), and hull nut (see
Figure 3). This will ensure there is sealant in the threads to seal
the hull and to hold the hull nut securely in place.
Installing
CAUTION: The arrow on the flange of the housing must point
forward toward the bow for the insert to be aligned properly.
CAUTION: The bottom of the insert must be flush with the bottom
of the housing for the sensor to work properly.
1. From outside the hull, push the housing into the mounting hole
using a twisting motion to squeeze out excess sealant (see
Figure 3). Align the arrow on the flange of the housing pointing
forward toward the bow. If the sensor is not installed on the
centerline, angle the housing slightly toward the centerline to
align it with the water flow.
2. From inside the hull, slide the washer onto the housing.
Aluminum hull less than 6mm (1/4") thick—Use an
additional rubbery, fiberglass, or plastic washer. Never use
bronze since electrolytic corrosion will occur. Never use wood,
since it will swell possibly fracturing the plastic housing.
3. Screw the hull nut in place being sure the notch on the upper
rim of the housing and the corresponding arrow on the flange
are still positioned forward toward the bow.
Plastic housing—Do not clamp tightly on the wrenching flats,
causing the housing to fracture.
Plastic hull nut—Hand-tighten only. Do not over-tighten.
Metal hull nut—Tighten with slip-joint pliers.
Cored fiberglass hull—Do not over tighten, crushing the hull.
Wood hull—Allow the wood to swell before tightening the hull nut.
4. Remove any excess sealant on the outside of the hull to ensure
smooth water flow under the ultrasonic insert.
5. After the sealant cures, inspect the o-rings on the valve
assembly (replace if necessary) and lubricate them with the
silicone lubricant supplied. The o-rings must be intact and well
lubricated to make a watertight seal.
6. Slide the valve assembly into the housing being sure to engage
the key in the notch.
7. Screw the cap nut in place. Hand-tighten only. Do not over tighten.
8. Inspect the o-rings on the ultrasonic insert (replace if
necessary) and lubricate them with the silicone lubricant
supplied (see Figure 6). The o-rings must be intact and well
lubricated to make a watertight seal.
9. Slide the ultrasonic insert into the housing with the arrow on the
top pointing forward toward the bow. Seat it into place with a
pushing twisting motion until the key fits into the notch. The
arrow on the top of the insert, the notch in the housing, and the
arrow on the flange will be aligned. Be careful not to rotate the
housing and disturb the sealant. Be sure the bottom of the insert
is flush with the bottom of the housing.
10.Attach one safety ring to one end of the retaining pin. Slide the
retaining pin through the valve assembly and the ultrasonic
insert. Attach the second safety ring to the retaining pin (see
Figure 3).
11.Attach the safety wire to prevent the insert from backing out in
the unlikely event that the cap nut fails or is screwed on
incorrectly.
Plastic housing—Attach the safety wire to one eye in the hull
nut. Thread the short emergency plug onto the wire. Keeping
the wire taut throughout, lead the wire in a counterclockwise
direction and thread it through one eye in the cap nut. Lead the
wire through the eye a second time. Then lead the wire through
the safety ring and the second eye in the cap nut. Twist the wire
end securely to itself.
Metal housing—Wrap one end of the safety wire tightly around
the housing and twist it together with the long end. Thread the
short emergency plug onto the wire. Keeping the wire taut
throughout, lead the wire straight up and through one eye in the
cap nut. Loop the wire through one safety ring. Twist the it
securely to itself.
12.To wire the ultrasonic speed sensor, follow the instructions
“Wiring” on page 5.
Checking for Leaks
When the boat is placed in the water, immediately check around
the sensor for leaks. Note that very small leaks may not be readily
observed. Do not to leave the boat in the water unchecked for more
than 3 hours. If there is a small leak, there may be considerable
bilge water accumulation after 24 hours. If a leak is observed,
repeat “Bedding” and “Installing” immediately (see page 3).
Installation in a Cored Fiberglass Hull
The core (wood or foam) must be cut and sealed carefully. The core must
be protected from water seepage and the hull must be reinforced to prevent
it from crushing under the hull nut allowing the housing to become loose.
CAUTION: Completely seal the hull to prevent water seepage into
the core.
1. Drill a 3mm or 1/8" pilot hole from inside the hull. If there is a rib, strut,
or other hull irregularity near the selected mounting location, drill from
the outside. (If the 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 a 51mm or 2" hole saw, cut the hole from outside the hull through
the outer skin only (see Figure 5).
3. From inside the hull, use a 60mm or 2-3/8" hole saw to cut through the
inner skin and most of the core. The core material can be very soft.
Apply only light pressure to the hole saw after cutting through the inner
skin to avoid accidentally cutting the outer skin.
4. Remove the plug of core material so the inside of the outer skin and the
inner core of the hull are fully exposed. Sand and clean the inner skin,
core, and the outer skin around the hole.
5. If you are skilled with fiberglass, saturate a layer of fiberglass cloth with
a suitable resin and lay it inside the hole to seal and strengthen the
core. Add layers until the hole is the correct diameter.
Alternatively, a hollow or solid cylinder of the correct diameter can be
coated with wax and taped in place. Fill the gap between the cylinder and
hull with casting epoxy. After the epoxy has set, remove the cylinder.
Figure 5. Preparing a cored fiberglass hull
inner skin
core
outer skin solid or hollow cylinder
pour in
casting
epoxy
9-12 mm
(3/8-1/2")
larger than the
hole through the
hull’s outer skin
hull thickness
Copyright © 2002 Airmar Technology Corp.