Airmar HT200 - Manual (Page 2)

Anti-fouling Paint
Aquatic growth can accumulate rapidly on the sensor’s surface reducing
performance within weeks. Surfaces exposed to salt water must be coated
with anti-fouling paint. Use water-based anti-fouling paint only. Never use
ketone-based paint, since ketones can attack many plastics possibly
damaging the sensor.
It is easier to apply anti-fouling paint before installing the sensor, but allow
sufficient drying time. Reapply paint every 6 months or at the beginning of
each boating season. Paint the following surfaces (see Figure 1):
• Bore of the valve assembly up 30mm (1-1/4")
• Exterior flange of the housing and valve assembly
• Blanking plug below the lower O-ring including the exposed end
• Temperature insert below the lower O-ring including the exposed end
• Paddlewheel insert:
--Outside wall below the lower O-ring
--Paddlewheel cavity
--Paddlewheel
Installation
Hole Drilling
Cored fiberglass hull—Follow separate instructions on page 4.
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.
2. Using the appropriate size hole saw, cut a hole perpendicular to the hull
from outside the boat.
Flush housing—Use a countersink tool to create a “seat” in the hull.
3. 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.
Metal hull—Remove all burrs with a file and sandpaper.
Bedding
CAUTION: Be sure the surfaces to be bedded are clean and dry.
Apply a 2mm (1/16") thick layer of marine sealant around the flange of the
housing that will contact the hull and up the sidewall of the housing (see
Figure 2). The sealant must extend 6mm (1/4") higher than the combined
thickness of the hull, washer, and hull nut. This will ensure there is sealant
in the threads to seal the hull and to hold the hull nut securely in place.
Stainless steel housing in a metal hull—The stainless steel housing
must be isolated from the metal hull to prevent electrolytic corrosion. Slide
the isolation bushing onto the housing. Apply additional sealant to the
surfaces of the bushing that will contact the hull, filling any cavities in and
around the bushing.
Installing
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. From outside the hull, push the housing into the mounting hole using a
twisting motion to squeeze out excess sealant (see 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.
Stainless steel housing in a 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 positioned
forward toward the bow.
Plastic housing—Do not clamp tightly on the wrenching flats, possibly
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 marine sealant on the outside of the hull to ensure
smooth water flow over the sensor.
5. After the marine sealant cures, inspect the O-rings on the valve
assembly (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 valve assembly into the housing. Seat it into place with a
pushing twisting motion until the key fits into the notch. Screw the CAP
nut in place and hand tighten only. Do not over tighten.
2
Figure 2. Bedding and installing (ST850 shown)
metal housing in non-metal hull
marine sealant
pull ring
paddlewheel insert
safety wire
cap nut
hull nut
washer
hull
emergency plug
on flange and sidewall
plastic housing stainless steel housing in metal hull
and sidewall of housing
marine sealant on flange
SS577 shown
insert nut
Copyright © 2005 - 2010 Airmar Technology Corp.
BOW ►
P17 shown B17 shown
of housing
and isolation bushing where it contacts hull
Figure 1. Anti-fouling paint (ST850 low-profile housing shown)
paddlewheel
cavity
paddlewheel
bore of
valve assembly
exterior flange
outside wall
paddlewheel
up 30mm (1-1/4")
insert
housing
lower O-ring
below
valve assembly
of housing and
Copyright © 2005 Airmar Technology Corp.