Airmar Shorty™ with Valve—S300 - Manual (Page 3)

not clamp tightly on the wrenching flats, possibly causing the
housing to fracture. Hand tighten only. Do not over tighten.
Cored fiberglass hull—Do not over tighten, crushing the hull.
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 paddlewheel
insert (replace if necessary) and lubricate them with the silicone
lubricant supplied (see Figure 3). The O-rings must be intact
and well lubricated to make a watertight seal.
6. Slide the paddlewheel 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, and the arrow on the
flange of the housing will all be aligned. Be careful not to rotate
the housing and disturb the sealant.
Screw the cap nut several turns, then check that the insert’s
arrow is still facing forward toward the bow. Continue to tighten
the cap nut. Hand tighten only. Do not over tighten.
7. Always 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. Attach the safety wire to one eye in the hull nut.
Lead the wire in a counterclockwise direction and thread it
through one eye in the cap nut. Twist the end securely to the
wire (see Figure 2).
Cable Routing & Connecting
CAUTION: If your sensor came with a connector, do not remove it
to ease cable routing. If the cable must be cut and spliced, use
Airmar’s splash-proof Junction Box No. 33-035 and follow the
instructions provided. Removing the waterproof connector or
cutting the cable, except when using a watertight junction box, will
void the sensor’s warranty.
1. 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.
2. 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 leave the boat in the water for more
than 3 hours before checking it again. 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 2).
Installation in a Cored Fiberglass Hull
CAUTION: Completely seal the hull to prevent water seepage into
the core.
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.
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 4).
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 is 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
CAUTION: Do not remove the screws on the top of the sensor.
To remove the insert, unscrew the cap nut. This will jack the insert
up. Then remove the cap nut and insert as a single unit.
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/temperature 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 (see Figures 1 and 5). Always
install the paddlewheel insert or blanking plug secured with the
safety wire for a watertight seal.
Using the Blanking Plug
To protect the paddlewheel insert, use the blanking plug:
• When the boat will be kept in salt water for more than a week.
• When the boat will be removed from the water.
• When aquatic growth build-up on the paddlewheel is
suspected due to inaccurate readings from the instrument.
3
Figure 4. 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 © 2000 Airmar Technology Corp.