Airmar ST200 User Manual

INSTALLATION INSTRUCTIONSOWNER’S GUIDE &

Thru-Hull, Retractable

Speed & Temperature Sensor

Models: ST200, ST550

Follow the precautions below for optimal product
performance and to reduce the risk of property
damage, personal injury, and/or death.

WARNING: Always wear safety goggles and a dust

mask when installing.

17-034 rev. 06 04/12/11

WARNING: The o-rings must be intact and well
lubricated to make a watertight seal.

WARNING: ST550—Always attach the safety wire to
prevent the insert or blanking plug from backing out in
the unlikely event that the cap nut fails or is screwed
on incorrectly.

WARNING: Immediately check for leaks when the boat
is placed in the water. Do not leave the boat unchecked
for more than three hours. Even a small leak may allow
considerable water to accumulate.

Record the information found on the cable tag for future reference.

Part No._________________Date___________

ST550

Applications

• Plastic housing recommended for fiberglass or metal hull only.

Never install a plastic housing in a wood hull, since swelling of
the wood may fracture the plastic.

• Bronze housing recommended for fiberglass or wood hull only.

Never mount a bronze housing in a metal hull because
electrolytic corrosion will occur.

CAUTION: Never pull, carry, or hold the sensor by its
cable; this may sever internal connections.

CAUTION: Never use a fairing with a plastic housing;
the protruding sensor would be vulnerable to damage
from impact.

CAUTION: Never install a metal housing on a vessel
with a positive ground system.

CAUTION: The arrow on the top of the insert points:

• ST200—rearward toward the stern

• ST550—forward toward the bow

CAUTION: Never use solvents. Cleaners, fuel,
sealants, paint, and other products may contain
strong solvents, such as acetone, which attack many
plastics, greatly reducing their strength.

IMPORTANT: Please read the instructions
completely before proceeding with the installation.
These instructions supersede any other instructions
in your instrument manual if they differ.

Pretest

Connect the sensor to the instrument and spin the paddlewheel.
Check for a speed reading and the approximate air temperature
(in appropriate). If there is no reading(s) or it is inaccurate, check
the connections and try again. If there is still a problem, return the
product to the place of purchase.

Tools & Materials

Safety goggles

Dust mask

Water-based anti-fouling paint (mandatory in salt water)

Electric drill with a 10mm (3/8") or larger chuck capacity

Drill bit: 3mm or 1/8"

Hole saw: ST200 44mm or 1-3/4"

ST550 51mm or 2"

Countersink tool (installing a P217 flush housing)

Sandpaper

Mild household detergent or weak solvent (alcohol)

File (installation in a metal hull)

Marine sealant (suitable for below waterline)

Washer or backing block (optional)

Mandatory for aluminum hull less than 6 mm (1/4") thick

Slip-joint pliers (installing a metal housing)

Grommet(s) (some installations)

Silicone grease or petroleum jelly (Vaseline

Cable ties

Installation is a cored fiberglass hull (see page 3):

Hole saw for hull interior: ST200 51mm or 2"

ST550 60mm or 2-3/8"

Fiberglass cloth and resin

or cylinder, wax, tape, and casting epoxy

®

)

Identify Your Model

The model name is printed on the cable tag.

outside wall of insert below lower O-ring, exposed end of insert,

paint paddlewheel, paddlewheel cavity,

bore of housing, and exterior flange

Figure 1. Anti-fouling paint (ST550 shown)

Copyright © 1997 Airmar Technology Corp.

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 300–6 00mm (1– 2').

• Full keel sailboats—Locate amidships and away from the keel
at the point of minimum deadrise.

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 30 mm (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 2 mm (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.

pull ring

retaining
pin

safety
ring

housing

hull nut
washer

(optional)

hull

ST200

marine sealant marine sealant

ST550

pull ring

safety wire

cap nut

housing

hull nut

washer

(optional)

hull

ST550

plastic housingmetal housing

marine sealant

Figure 2. Bedding and installation

Copyright © 1997 Airmar Technolog y Corp.

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