Airmar ST200 - Manual (Page 2)

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).
• Outside wall of the paddlewheel insert below the lower o-ring
• Exposed end of the paddlewheel insert
• Paddlewheel cavity
• Paddlewheel
• Bore of housing up 30mm (1-1/4")
• Exterior flange of the housing
• Blanking plug below the lower o-ring and the exposed end
Installation
Hole Drilling
Cored fiberglass hull—Follow separate instructions on page 3.
1. Drill a 3mm or 1/8" pilot hole from inside the hull. If there is a rib,
strut or other hull irregularity, drill from the outside.
2. Using the appropriate hole saw, cut the hole perpendicular from
outside 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 (see Figure 2)
CAUTION: Be sure the surfaces to be bedded are clean and dry.
1. ST200—Remove one safety ring, the retaining pin, the
paddlewheel insert, the hull nut, and any washer.
ST550—Remove the cap nut, paddlewheel insert, the hull nut,
and any washer.
2. 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. The sealant must extend 6mm (1/4")
higher than the combined thickness of the hull, any washer, and
the hull nut. This will ensure there is sealant in the threads to
seal the hull and to hold the hull nut securely in place.
Figure 2. Bedding and installation
pull ring
cap nut
washer
hull
plastic housing metal housing
safety wire
(optional)
ST550
safety
ring
retaining
pin
ST200
housing
housing
Mounting Location
CAUTION: Do not mount the sensor near water intake or
discharge openings; behind strakes, fittings, or hull irregularities
that will disturb the water flow.
CAUTION: Never mount the sensor directly ahead of a depth
transducer, since turbulence generated by the paddlewheel’s
rotation will adversely affect the depth transducer’s performance,
especially at high speeds. Mount side by side.
CAUTION: Do not mount in line with trailer rollers or bunks that
may damage the transducer’s face.
Turbulence-free water must flow under the paddlewheel at all
boat speeds. Choose an accessible spot inside the vessel. Allow
headroom for the height of the housing, tightening the nuts, and
installing the insert.
ST200 18cm (7")
ST550 28cm (11")
• Displacement hull powerboats—Locate amidships near the
centerline.
• Planing hull powerboats—Mount well aft to ensure the sensor
is in contact with the water at high speeds.
• Fin keel sailboats—Mount on or near the centerline and
forward of the fin keel 300–600mm (1–2').
• Full keel sailboats—Locate amidships and away from the keel
at the point of minimum deadrise.
hull nut
pull ring
hull nut
washer
(optional)
hull
marine sealant marine sealant marine sealant
Copyright © 1997 Airmar Technology Corp.
ST550
Figure 1. Anti-fouling paint (ST550 shown)
paint paddlewheel, paddlewheel cavity,
outside wall of insert below lower O-ring, exposed end of insert,
bore of housing, and exterior flange
Copyright © 1997 Airmar Technology Corp.