Airmar ST600 User Manual

INSTALLATION INSTRUCTIONSOWNER’S GUIDE &

Thru-Hull, Retractable with Valve

Speed & Temperature Sensor

Model ST600

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.

WARNING: The valve is not a watertight seal! Always
use the insert or blanking plug secured with the safety

17-038-01 rev. 04 04/12/11

wire for a watertight seal.

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

WARNING: 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.

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

CAUTION: The arrow on the top of the insert must
point 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.

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 wood or fiberglass hull only.

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

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.

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

Part No._________________Date___________

Tools & Materials

Safety goggles
Dust mask
Water-based anti-fouling paint (mandatory in salt water)
Electric drill with 10 mm (3/8") or larger chuck capacity
Drill bit: 3mm or 1/8"
Hole saw: 51mm or 2"
Sandpaper
Mild household detergent or weak solvent (alcohol)
File (installation in a metal hull)
Marine sealant (suitable for below waterline)
Additional washer [for aluminum hull less than 6mm (1/4") thick]
Slip-joint pliers (installing a metal housing)
Grommet(s) (some installations)
Cable ties
Installation in a cored fiberglass hull (see page 3)

Hole saw for hull interior: 60mm or 2-3/8"
Fiberglass cloth and resin
or Cylinder, wax, tape, and casting epoxy

Mounting Location

CAUTION: Do not mount the sensor near water intake or

discharge openings; behind strakes, fittings, or hull irregularities
that will disturb the 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
speeds. Choose an accessible spot inside the vessel. Allow a
minimum of 200mm (8") of headroom for the height of the
housing, tightening the nuts, and removing the insert.

• Displacement hull powerboats—Locate amidships near the
centerline.

• Planing hull powerboats—Mount well aft to ensure that it 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.

paddlewheel
insert

outside wall
below
lowest o-ring

paddlewheel

paddlewheel
cavity

housing

paddlewheel

insert

pull
ring

cap
nut

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 near the selected mounting
location, drill from the outside.

2. Using the 51mm or 2" hole saw, cut the hole perpendicular to
the hull from outside.

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.

exterior flange
of housing

bore of housing
up 30mm (1-1/4")

Figure 1. Anti-fouling paint

Copyright © 2001 Airmar Technology Corp.

Figure 2. Assembly

Copyright © 2001 Airmar Technolog y Corp.

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 anti-fouling paint,
since ketones attack many plastics possibly damaging the sensor.

It is easier to apply anti-fouling paint before installation, 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 paddlewheel insert below lowest o-ring

• Paddlewheel cavity

• Paddlewheel

• Bore of housing up 30mm (1-1/4")

• Exterior flange of housing

• Blanking plug below lowest o-ring including the exposed end

Assembly

Slide the cap nut along the cable until it rests on the top of the
paddlewheel insert. Attach the pull ring to the insert capturing the
cap nut (see Figure 2). Similarly attach the pull ring to the blanking
plug capturing the cap nut.

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 contacts the hull and up the sidewall of
the housing (see Figure 3). 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.

Installing

1. From outside the hull, push the housing into the mounting hole
using a twisting motion to squeeze out excess sealant (see
Figure 3). Align the arrow on the flange of the housing to point
forward toward the bow. If the sensor is not installed on the
centerline of the boat, 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.
Aluminum hulls less than 6mm (1/4") thick—Use an
additional rubbery, plastic, or fiberglass washer. Never use a
wood backing block, since swelling of the wood can overstress
the plastic housing causing a fracture. Never use bronze since
electrolytic corrosion will occur.

3. Screw the hull nut in place being sure the notch on the upper rim
of the housing and the arrow on the flange are still positioned
forward toward the bow (see Figure 7).
Plastic housing—Do not clamp tightly on the wrenching flats,
causing the housing to fracture.

Plastic hull nut—Hand-tighten only. Do not over tighten.
Metal hull nut—Tighten the hull nut with slip-joint pliers.

2

paddlewheel
insert

marine

sealant

plastic housing metal housing

pull ring

safety wire

cap nut

(plastic)

hull nut

washer

hull

Figure 3. Bedding and installing

Copyright © 2001 Airmar Technology Cor p.

paddlewheel
insert

marine
sealant

Cored fiberglass hull—Do not over tighten, crushing the hull.
Wood hull—Allow the wood to swell before tightening the nut.

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. 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 in place
and hand-tighten only. Do not over tighten (see Figure 3).

7. 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.
Plastic housing—Attach the safety wire to one eye in the hull
nut. Keeping the wire taut throughout, lead the wire in a
counterclockwise direction and thread it through one eye in the
cap nut, the pull ring, the second eye in the cap nut, and the
second eye in the hull nut. 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. Keeping the
wire taut throughout, lead the wire straight up and through the
eye in the cap nut. Loop the wire through the pull ring and twist
it securely to itself.

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 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 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 using 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
unchecked for more than 3 hours. 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.)

9-12 mm

pour in
casting
epoxy

hull thickness

Figure 4. Preparing a cored fiberglass hull

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. Clean and sand 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 the “Bedding” and “Installing” on page 2.

(3/8- 1/2")
larger than the
hole through the
hull’s outer skin

Copyright © 2001 Airmar Technolog y Corp.

inner skin

core

outer skinsolid or hollow cylinder

Operation, Maintenance, Repair & Parts

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 boat
when the paddlewheel 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 use the paddlewheel insert or the

blanking plug secured with the safety wire for a watertight seal.

Using the Blanking Plug

To protect the paddlewheel, use the blanking plug when:

• The boat will be kept in salt water for more than a week.

• The boat will be removed from the water.

• Aquatic growth build-up on the paddlewheel is suspected due
to inaccurate readings from the instrument.

1. On the blanking plug, inspect the o-rings (replace if necessary)
and lubricate them with the silicone lubricant supplied or
petroleum jelly (Vaseline®). The o-rings must be intact and well
lubricated to make a watertight seal.

2. Remove the paddlewheel insert from the housing by removing
the safety wire and unscrewing the cap nut (see Figure 3).

3. Grasp the pull ring and remove the paddlewheel insert with a
slow pulling motion.

NOTE: In the unlikely event that the paddlewheel insert cannot
be removed, see “Servicing the Valve Assembly” on page 4.

4. Slide the blanking plug into the housing with the arrow on the
top pointing forward toward the bow. Seat it into place with a

3

top view

side view

BOW ►

Figure 5. Paddlewheel &

Valve Kit 33-250

Copyright © 2001 Airmar Technology Corp. Copyright © 2001 Airmar Technolo gy Corp.

Figure 6. Replacing the paddlewheel

and o-rings

arrow

pull ring

large o-ring

medium o-ring
small o-ring

shaft

flat side
of blade
faces bow

snap ring

valve assembly

flap valve
spring
retainer pin

notch

housing

Figure 7. Servicing the

valve assembly

Copyright © 2001 Airmar Technology Corp.

pushing twisting motion until the key fits into the notch. Screw
the cap nut in place. Hand-tighten only. Do not over tighten.

5. Reattach the safety wire to prevent the insert from backing out in

the unlikely event that the cap nut fails or is screwed on incorrectly.

Cleaning the Paddlewheel

Aquatic growth can impede or freeze the paddlewheel’s rotation
and must be removed. Clean the surface using a Scotch-Brite®
scour pad and mild household detergent. If fouling is severe, push
out the paddlewheel shaft using a spare shaft or a 4D finish nail
with a flattened point. Then, lightly wet sand the surface with fine
grade wet/dry paper.

Replacing the Paddlewheel & O-rings

The water lubricated paddlewheel bearings have a life of up to 5
years on low-speed boats [less than 10kn (11 MPH)] and 1 year
on high-speed vessels. Paddlewheels can fracture and shafts can
bend due to impact with water borne objects and mishandling in
boat yards. O-rings must be free of abrasions and cuts to ensure
a watertight seal. A replacement Paddlewheel & Valve Kit 33-250
is available (see Figure 5).

1. Using the new paddlewheel shaft, push the old shaft out about
6mm (1/4"). With pliers, remove the old shaft (see Figure 6).

2. Place the new paddlewheel in the cavity with the flat side of the
blade facing the same direction as the arrow on the insert top.

3. Tap the new shaft into place until the ends are flush with the insert.

4. Install a large o-ring near the pull ring, a medium o-ring below it,
and a small o-ring near the paddlewheel.

5. Place the three remaining o-rings in similar positions on the
blanking plug.

Servicing the Valve Assembly

Should the valve fail, remove it for servicing.

1. On the blanking plug, inspect the o-rings (replace if necessary)
and lubricate them with the silicone lubricant supplied or
petroleum jelly (Vaseline®). The o-rings must be intact and well
lubricated to make a watertight seal.

2. Remove the paddlewheel insert from the housing (see Figure 3).

3. Remove the snap ring from the valve assembly using a screw­driver to pry the end of the ring free. Lift the ring out (see Figure 7).

4. Slide the valve assembly upward and out of the housing slowly.

®

AIRMAR

TECHNOLOGY CORPORATION

4

Copyright © 1997 - 2011 Airmar Technology Corp. All rights reserved.

www.airmar.com

NOTE: The flap valve retainer pin is a loose slip-fit and may
slide out when the assembly is removed.

5. Hold the cap nut on the blanking plug while sliding it into the
housing with the arrow on the top pointing forward toward the
bow. Seat the plug 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. Reattach the safety wire (see Figure 3).

6. Clean, repair, or replace the valve assembly so the flap valve
moves freely and seats against the valve housing.

7. To reinstall the valve assembly, first reassemble the flap valve
in the valve housing with the retainer pin and spring in place
(see Figure 7).

8. Remove the blanking plug. Slide the valve assembly into the
housing with the flap valve pointing downward. Insert the snap ring
being certain that it locks into the groove in the housing wall.

9. Hold the cap nut on the blanking plug while sliding it into the
housing. Be sure the arrow on the top is pointing forward
toward the bow. Seat it into place with a pushing twisting motion
until the key fits into the notch. Screw the cap nut in place.
Hand-tighten only. Do not over tighten.

10.Reattach the safety wire to prevent the insert from backing out
in the unlikely event that the cap nut fails or is screwed on
incorrectly (see Figure 3).

Winterizing

After the boat has been hauled for winter storage, remove the blanking
plug to let the water drain away before reinserting it. This will prevent any
water from freezing around the blanking plug and possibly cracking it.

Replacement Sensor & Parts

The information needed to order a replacement Airmar transducer is
printed on the cable tag. Do not remove this tag. When ordering, specify
the part number and date. For convenient reference, record this information
on the top of page one.

If you have purchased a plastic housing and have a wood hull or desire
greater strength, purchase a metal housing. Lost, broken, or worn parts
should be replaced immediately.

Blanking

Plug Kit

20-600

Obtain parts from your instrument manufacturer or marine dealer.

Gemeco Tel: [phone]
(USA) Fax: [phone]

Airmar EMEA Tel: [phone]
(Europe, Middle East, Africa) Fax: [phone]

Cap Nut Hull Nut

04-234-1 (plastic)
02-131-01 (bronze)

04-004 (plastic)
02-030 (bronze)

email: [e-mail]

email: [e-mail]

Housing

& Hull Nut Kit

33-340-02 (plastic)
33-340-01 (bronze)

Pdlwhl &
Valve Kit

33-250