Airmar DST800 Retractable without Valve—TRIDUCER® Multisensor - Manual (Page 3)

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 appropriate size hole saw, cut a hole perpendicular to the
hull from outside the boat.
Flush housing—Use a countersink tool to make 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 3). The sealant must extend 6mm (1/4") higher
than the combined thickness of the hull, the washer(s), and the hull
nut. This will ensure there is marine 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 multisensor 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 water-tight
junction box, will void the sensor warranty.
1. From outside the hull, push the housing into the mounting hole
using a twisting motion to squeeze out excess marine sealant
(see Figure 3). Align the arrow on the flange of the housing to
point forward toward the bow. If the multisensor 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 hull less than 6mm (1/4") thick—Use an
additional rubbery, fiberglass, or plastic washer. Never use
bronze since electrolytic corrosion will occur. Never use wood
since it will swell, possibly fracturing the plastic 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 arrow on the flange of
the housing is 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 nut.
4. Remove any excess marine sealant on the outside of the hull to
ensure smooth water flow over the multisensor.
5. After the marine sealant cures, inspect the O-rings on the 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. Be sure the insert is
fully inserted into the housing. Screw the cap nut several turns
until the threads are engaged. The arrow on the top of the
insert, the cable exit, and the arrow on the housing flange will all
be aligned. Continue to tighten the cap nut completely for a
watertight seal. Be careful not to rotate the housing and disturb
the sealant. Hand tighten only. Do not over tighten.
7. Always 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. Thread the wire through the eye a second time. Then
lead the wire through the eye in the insert. 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 one
eye in the cap nut. Thread the wire through the eye a second
time. Then lead the wire counterclockwise and through the eye
in the insert. Twist the wire securely to itself.
8. Route the cable to the instrument being careful not to tear the
cable jacket when passing it through the bulkhead(s) and other
parts of the boat. Use grommet(s) to prevent chaffing. To
reduce electrical interference, separate the multisensor cable
from other electrical wiring and the engine. Coil any excess
cable and secure it in place with cable ties to prevent damage.
9. Refer to the instrument owner’s manual to connect the
multisensor to the instrument.
Checking for Leaks
When the boat is placed in the water, immediately check around
the thru-hull multisensor for leaks. Note that very small leaks may
not be readily observed. Do not leave the boat in the water for
more than 3 hours before checking it again. 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 3.
Installation in a Cored Fiberglass Hull
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.
CAUTION: Completely seal the hull to prevent water seepage into
the core.
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.)
2. Using a 51mm or 2" hole saw, cut the hole from outside the hull
through the outer skin only (see Figure 4).
3