Airmar TRIDUCER UDST800 Technical Document

Thru-Hull, Retractable with Valve
Ultrasonic TRIDUCER®Multisensor
Smart™Sensor
Model UDST800
17-633-01-rev01 08/12/17
Record the information found on the cable tag for future reference.
Part No._________________Date___________Frequency________kHz
How the Ultrasonic Speed Sensor Works
The speed sensor uses ultrasonic pulses to collect echoes from
small particles in the water as they pass under two transducers
embedded in the insert (Figure 1). These transducers monitor the
particles in their respective beams. As the boat travels through the
water, both transducers ‘view’ the same stream of particles.
Because it takes time for particles to travel between the two
transducers, the aft transducer detects the particles later than
does the fore transducer. By measuring this time lapse, the
instrument calculates the boat speed. If the boat is airborne, even
for a short time, or in highly aerated water, the sensor will
measure an incorrect speed.
plastic
low profile
P617V housing
UDST800
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 glasses, a dust mask,
and ear protection when installing.
WARNING: The valve is not a watertight seal!
Always install the ultrasonic insert or blanking plug. Be sure
it is fully inserted into the housing and the cap nut is screwed
on completely for a watertight seal.
WARNING: The ultrasonic insert/blanking plug must
be installed in a housing with a valve.
WARNING: The YELLOW O-ring must be in place
near the top of the insert to make a watertight seal.
WARNING: To retrofit the insert in a housing without
a valve, the insert must have a BLACK O-ring near the
top to make a watertight seal.
WARNING: The O-rings must be intact and well
lubricated to make a watertight seal.
WARNING: 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.
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: Plastic housing—Never use a fairing with
a plastic housing; the protruding multisensor would be
vulnerable to damage from impact.
CAUTION: Stainless steel housing in a metal hull—
Stainless steel housing must be isolated from a metal
hull to prevent electrolytic corrosion. Use the isolation
bushing supplied.
CAUTION: Metal housing—Never install a metal
housing in a vessel with a positive ground system.
CAUTION: Never pull, carry, or hold the transducer by
its cable; this may sever internal connections.
INSTALLATION INSTRUCTIONSOWNER’ S GUIDE &
CAUTION: The arrow on the top of the ultrasonic
insert must point forward toward the bow to align with
the water flow.
CAUTION: Never use solvents. Cleaner, fuel, sealant,
paint, and other products may contain solvents that can
damage plastic parts, especially the transducer’s face.
IMPORTANT: Read the instructions completely
before proceeding with the installation. These
instructions supersede any other instructions in your
instrument manual if they differ.
scanning transducer
FORE AFT
hull
vessel direction
particle stream
Figure 1. Monitoring particles in the water
Copyright © 2002 Airmar Technology Corp.
U.S. Patent No.: 6,426,918; 6,671,225; 6,678,208; 9,513,373; 9,594,165
EP Patent No.: 1 634 087

Applications
• Not recommended for boats designed to pull air under the hull.
•Plastic housing recommended for fiberglass or metal hull only.
Never install a plastic housing in a wood hull, since swelling of
the wood can possibly fracture the plastic.
•Bronze housing recommended for fiberglass or wood hull.
Never mount a bronze housing in an aluminum hull because
electrolytic corrosion will occur.
•Stainless steel housing compatible with all hull materials.
Recommended for aluminum hulls to prevent electrolytic
corrosion provided the stainless steel housing is isolated from
the metal hull.
• Accommodates up to a 22° deadrise angle.
Tools & Materials
Safety glasses
Dust mask
Ear protection
Water-based anti-fouling paint (mandatory in salt water)
Electric drill with 10mm (3/8") or larger chuck capacity
Drill bit for pilot hole 3mm or 1/8"
Hole saw:
Plastic or metal housing in non-metal hull 51mm or 2"
Stainless steel housing in metal hull 57mm or 2-1/4"
Sandpaper
Mild household detergent or weak solvent (such as alcohol)
File (installation in a metal hull)
Marine sealant (suitable for below waterline)
Slip-joint pliers (installing a metal housing)
Grommet(s) (some installations)
Cable ties
Installation in a cored fiberglass hull (see page 4):
Hole saw for hull interior 60mm or 2-3/8"
Fiberglass cloth and resin
or Cylinder, wax, tape, and casting epoxy
Anti-fouling Paint
Aquatic growth can accumulate rapidly on the multisensor’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
multisensor.
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
(Figure 1):
• Outside wall of the insert below the lowest O-ring
• Active face of the insert
• Exterior flange of the housing
• Bore of the housing up 30mm (1-1/4")
• Blanking plug below the lower O-ring including the exposed end
Mounting Location
CAUTION: Do not mount in line with or near water intake or
discharge openings, or behind strakes, fittings, or hull
irregularities that will disturb the water flow.
• The water flowing under the hull must be smooth with a
minimum of bubbles and turbulence (especially at high speeds).
• The multisensor must be continuously immersed in water.
• The transducer beam must be unobstructed by the keel or
propeller shaft(s).
• Choose a location away from interference caused by power and
radiation sources such as: the propeller(s) and shaft(s), other
machinery, other echosounders, and other cables. The lower
the noise level, the higher the echosounder gain setting that
can be used.
• Choose a location with a minimum deadrise angle, so the
transducer beam will be aimed at the bottom.
• Choose an accessible spot inside the vessel with a minimum of
280mm (11") for the height of the housing, tightening the nuts,
and installing the insert.
Boat Types (Figure 2)
•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.
•Displacement hull powerboats—Locate amidships near the
centerline. The starboard side of the hull where the propeller
blades are moving downward is preferred.
•Planing hull powerboats—Mount well aft to ensure the sensor
is in contact with the water at high speeds.
2
outside wall
bore of housing
exterior flange
O-ring
below lowest
up 30mm (1-1/4")
of housing
ultrasonic insert
housing
active face
Figure 1. Anti-fouling paint
Copyright © 2017 Airmar Technology Corp
Figure 2.
full keel sailboats
large displacement hulls small displacement hulls
fin keel sailboats
Best location for multisensor
Copyright © 2017 Airmar Technology Corp

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 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 contacts the hull and up the sidewall of
the housing. The sealant must extend 6mm (1/4") higher than the
combined thickness of the hull, the washer, and the hull nut
(Figure 3). 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—A stainless steel
housing must be isolated from a 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: The arrow on the flange of the housing must point
forward toward the bow for the insert to be aligned properly.
CAUTION: The bottom of the insert must be flush with the bottom
of the housing for the multisensor to work properly.
1. From outside the hull, push the housing into the mounting hole
using a twisting motion to squeeze out excess sealant (Figure 3).
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.
Plastic housing—Do not clamp tightly on the wrench flats,
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 for 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 under the multisensor.
5. The O-rings must be intact and well lubricated to make a
watertight seal. After the marine sealant cures, inspect the
O-rings, including the YELLOW O-ring, on the insert (replace if
necessary) and lubricate them with the silicone lubricant
supplied. Also lubricate the bore of the housing above the valve.
6. The insert must be fully inserted into the housing and the cap
nut screwed on completely to make a watertight seal. Slide the
insert into the housing with the arrow on the top pointing
forward toward the bow. Screw the cap nut several turns until
the threads are engaged. Being sure the arrow on the top of the
insert and the cable exit are pointing forward toward the bow,
continue to tighten the cap nut completely. Be careful not to
rotate the housing and disturb the sealant. Hand tighten only.
Do not over tighten.
3
Figure 4. Preparing a cored fiberglass hull
inner skin
core
outer skin
solid or hollow cylinder
pour in
casting
epoxy
9-12 mm
(3/8-1/2")
larger than the
hole through the
hull’s outer skin
hull thickness
Copyright © 2017 Airmar Technology Corp
marine sealant on flange
Figure 3. Bedding and installing
cap nut
washer
hull
plastic housing
safety wire
housing
hull nut
insert
marine sealant on flange
stainless steel housing in metal hullmetal housing in non-metal hull
isolation
bushing
washer
and sidewall of housing
(plastic)
marine sealant on flange
cap nut
hull
safety wire
housing
insert
(plastic)
(metal)
hull nut
Copyright © 2017 Airmar Technology Corp
(P617V shown) (SS617V shown)
and sidewall of housing and sidewall of housing and isolation bushing where it contacts hull
BOW ►
(B617V shown)

4
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.
Installing in Housing WITHOUT Valve
To create a watertight seal in a housing that does NOT have a valve,
the insert must have a BLACK O-ring near the top. Use Replacement
O-ring Kit 20-519-01 and follow the instructions supplied.
Cable Routing & Connecting
Follow the instructions supplied with the Ultrasonic Processor.
Checking for Leaks
When the boat is placed in the water, immediately check around
the multisensor for leaks. Note that very small leaks may not be
readily observed. Do not to 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 (Figure 4).
3. From inside the hull, use a 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. Sand and clean
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 marine 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 “Bedding” (see page 3).
Operation, Maintenance, & Parts
How the Valve Works
THE VALVE IS NOT A WATERTIGHT SEAL! The multisensor
incorporates a self-closing valve which minimizes the flow of
water into the boat when the 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 install the insert or the
blanking plug secured with the cap nut and safety wire for a
watertight seal.
Using the Blanking Plug
To protect the insert, use the blanking plug:
• When the boat will be kept in salt water for more than a week.
• When the boat will be removed from the water.
• When aquatic growth buildup on the paddlewheel is suspected
due to inaccurate readings from the instrument.
1. The O-rings must be intact and well lubricated to make a
watertight seal. On the blanking plug, inspect the O-rings
(replace if necessary) and lubricate them with the silicone
lubricant supplied or petroleum jelly (Vaseline®) (Figure 5).
2. Remove the insert from the housing by removing the safety wire
and unscrewing the cap nut (Figure 3). This will jack up the
insert. Remove the insert with a slow pulling motion. Replace it
by sliding the blanking plug into the housing.
NOTE: In the very unlikely event that the valve breaks, replace
the housing the next time the boat is hauled.
3. With the blanking plug fully inserted, screw the cap nut several
turns until the threads are engaged. Continue to tighten the cap
nut completely. Hand tighten only. Do not over tighten.
NOTE: The blanking plug must be fully inserted in the housing
and the cap nut screwed on completely for a watertight seal.
4. Reattach the safety wire to prevent the blanking plug from
backing out in the unlikely event that the cap nut fails or is
screwed on incorrectly.
Figure 5. Replacing the O-rings
arrow
blanking
insert
yellow
O-ring
small
O-rings (2)
Copyright © 2017 Airmar Technology Corp
BOW ►
plug
active face

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.
Servicing the Ultrasonic Insert
CAUTION: The active face of the ultrasonic insert is easily
damaged. Do not scratch, gouge, or sand it with coarse
sandpaper.
Aquatic growth will seriously affect the performance of the
ultrasonic insert. Clean the active face with a dull putty knife,
being careful to avoid scratching the surface (Figure 5). If fouling
is severe, lightly wet sand the active face with fine grade (#320)
wet/dry paper.
O-rings must be free of abrasions and cuts to ensure a watertight
seal. Install the o-rings on the ultrasonic insert as shown
(Figure 5). The remaining o-rings are placed in similar positions
on the blanking plug.
Replacement Multisensor & Parts
The information needed to order a replacement Airmar
multisensor is printed on the cable tag. Do not remove this tag.
When ordering, specify the part number, date, and frequency in
kHz. For convenient reference, record this information on the top
of page one.
Lost, broken, or worn parts should be replaced immediately. If you
have purchased a plastic housing and have a wood hull or desire
greater strength, purchase an Airmar metal housing.
Obtain parts from your instrument manufacturer or marine dealer.
Gemeco USA
Tel: [phone]
email: [email protected]
Airmar EMEA Europe, Middle East, Africa
Tel: [phone]
email: [email protected]
Blanking
Plug
Hull Nut or
Isolation Bushing Housing, Hull Nut & Washer
20-542-01
04-004 (plastic)
02-030 (bronze)
02-530-02 (stainless steel)
04-186-1 (isolation bushing)
with Valve:
33-510-01 (plastic, P617V)
33-588-01 (bronze, B617V)
33-617-01 (stainless steel, SS617V)
NO Valve:
33-100 bronze, low-profile, B17
33-224-01 bronze, flush, B21
5

6Copyright © 2017 Airmar Technology Corp. All rights reserved.
35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA
•www.airmar.com