Installation Instructions

ManualsBrandsFuruno ManualsSensorsFuruno ST-02PSB

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.

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

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