Airmar HT200 - Manual (Page 3)

Figure 3. Servicing
paddlewheel
flat side of
shaft
blade faces
small
valve
housing
valve housing
flap valve
insert
pull ring
cap nut
key
O-rings
assembly
direction of arrow on top
temp.
insert
insert nut
medium O-rings
Copyright © 2005 - 2010 Airmar Technology Corp.
BOW ►
of insert (toward bow)
paddlewheel
7. Slide the insert nut along the cable until it rests on the top of the insert.
Attach the pull ring to the insert, capturing the insert nut.
8. Inspect the O-rings on the paddlewheel/temperature insert (replace if
necessary) and lubricate them with the silicone lubricant supplied.
9. Slide the insert into the housing. Seat it into place with a pushing twisting
motion until the key fits into the notch. Be careful not to rotate the housing
and disturb the sealant. Screw the INSERT nut in place and hand tighten
only. Do not over tighten.
ST850—The paddlewheel insert must have the arrow on the top pointing
forward toward the bow. (The cable exit points away from the bow.)
10.Always attach the safety wire to prevent the insert from backing out in
the unlikely event that the insert nut and/or cap nut fails or is screwed
on incorrectly (see Figure 2).
Plastic housing—Attach the safety wire securely 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 in a counterclockwise direction
and thread it through the eye in the INSERT nut. Thread the wire
through the eye a second time. Loop the wire through the pull ring and
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. Thread the wire
through the eye a second time. Lead the wire in a counterclockwise
direction and thread it through the eye in the INSERT nut. Thread the
wire through the eye a second time. Loop the wire through the pull ring
and twist the wire securely to itself.
11.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 grommet(s) 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. Refer to the instrument owner’s manual to connect
the sensor to the instrument.
Retrofit Into ST650 Housing
The HT200 and ST850 insert can be installed in a new or existing ST650
housing. However, the ST650 valve assembly inside the housing
must be replaced with the HT200/ST850 valve assembly, so the new
insert will fit. To replace the valve assembly, follow the instructions
“Servicing the Valve Assembly” on page 4.
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
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 4).
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
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.
Always install the paddlewheel/temperature insert or the long blanking plug
secured with the INSERT nut and safety wire for a watertight seal.
3
or
blanking
plug
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 © 2005 Airmar Technology Corp.