Airmar S650 - Manual (Page 3)

Figure 2). Align the arrow on the flange of the housing to point
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 wood since it will swell,
possibly fracturing the plastic housing. Never use bronze since
electrolytic corrosion will occur.
Stainless steel transducer in metal hull—Be sure the washer contacts
the hull. Do not tighten the hull nut with the washer against the isolation
bushing, as the housing will not be firmly installed. If necessary, sand the
isolation bushing until the washer rests against the hull.
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
pointing 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 paddlewheel.
5. After the sealant cures, inspect the o-rings on the valve
assembly (replace if necessary) and lubricate them with the
silicone lubricant supplied (see Figure 4). 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. Screw the plastic cap nut in place and
hand tighten only. Do not over tighten.
7. Attach one pull ring to the paddlewheel insert. Similarly, attach
a pull ring to the blanking plug.
8. Inspect the o-rings on the paddlewheel insert (replace if
necessary) and lubricate them with the silicone lubricant supplied.
9. Slide the paddlewheel insert into the housing with the arrows on
the top pointing forward toward the bow. Seat it into place with a
pushing twisting motion until the keys fit into the notches. The
arrows 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.
10.Attach one safety ring to one end of the retaining pin. Slide the
retaining pin through the valve assembly and paddlewheel insert.
Attach the second safety ring to the retaining pin (see Figure 2).
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. Thread the wire through the eye a
second time. Then lead the wire through the pull ring and the second eye
in the cap nut. Twist the wire 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 the pull ring and twist
it securely to itself.
12.Route the cable to the instrument being careful not to tear the
cable jacket when passing it through the bulkhead(s) and other
parts of the boat. Use grommets to prevent chafing. To reduce
electrical interference, separate the sensor cable from other
electrical wiring and the engine. Coil any excess cable and
secure it in place with cable ties to prevent damage.
13.Refer to the instrument owner’s manual to connect the sensor
to the instrument.
Checking for Leaks
When the boat is placed in the water, immediately check around
the thru-hull 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 hour. If a
leak is observed, repeat “Bedding” and “Installing” immediately
(see on page 2).
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 the 51mm or 2" hole saw, cut the hole from outside the hull
through the outer skin only (see Figure 3).
3. From inside the hull, use the 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.
6. Sand and clean the area around the hole, 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 (alcohol) before sanding.
7. Proceed with “Bedding” and “Installing” on page 2.
Operation, Maintenance, Repair & Parts
How the Valve Works
The valve is not a watertight seal! The sensor incorporates a self-
closing valve which minimizes the flow of water into the vessel when the
paddlewheel insert is removed. The curved flap valve is activated by both
a spring and water pressure. Water pushes the flap valve upward to block
the opening so there is no gush of water into the boat. Always install the
paddlewheel insert or the long blanking plug secured with the retaining
pin, safety rings, and safety wire for a watertight seal.
3
Figure 3. 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 © 1996 Airmar Technology Corp.