3. If the degradation is sudden (not gradual), identify the boat
speed at which the onset occurred. Return the boat to this
speed, then gradually increase speed while making moderate
turns in both directions.
4. If the performance improves while turning, the transducer’s
position probably needs adjustment. It is probably in aerated
water. Move the transducer farther down into the water in
increments of 3mm (1/8"). If the performance does not improve
satisfactorily, move the sensor closer to the centerline of the
boat. Fill unused screw holes with marine sealant.
High-speed operation
(above 40MPH) may require less
projection in the water to improve performance and reduce the
chance that water pressure will cause the bracket to release.
5.
Calibration
—To match the speed shown on the display to the
actual speed of the boat, you may need to calibrate the
instrument. Refer to your instrument owner’s manual.
Cable Routing
Route the sensor cable over the transom, through a drain hole, or
through a new hole drilled in the transom
above the waterline
.
Caution
: Never cut the cable or remove the connector; this will
void the warranty.
Warning
: Always wear safety goggles and a dust mask.
1. If a hole must be drilled through the transom, choose a location
well above the waterline
(see Figure 11). Check for
obstructions such as trim tabs, pumps, or wiring inside the hull.
Mark the location with a pencil. Drill a hole using the appropriate
size bit to accommodate the connector.
2. Route the cable over or through the transom.
3. On the outside of the hull secure the cable against the transom
using the cable clamps. Position a cable clamp 50mm (2")
above the bracket and mark the mounting hole with a pencil.
4. Position the second cable clamp halfway between the first
clamp and the cable hole. Mark this mounting hole.
5. If a hole has been drilled in the transom, open the appropriate slot in the
cable cover. Position the cover over the cable where it enters the hull.
Mark the two mounting holes.
6. At each of the marked locations, use a 3mm or 1/8" bit to drill a hole
10mm (3/8") deep. To prevent drilling too deeply, wrap masking tape
around the bit 10mm (3/8") from the point.
7. Apply marine sealant to the threads of the #6 x 1/2" self-tapping screws
to prevent water from seeping into the transom. If you have drilled a hole
through the transom, apply marine sealant to the space around the cable
where it passes through the transom.
8. Position the two cable clamps and fasten them in place. If used, push
the cable cover over the cable and screw it in place.
9. 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. To
reduce electrical interference, separate the sensor cable from other electrical
wiring and the engine(s). Coil any excess cable and secure it in place with
zip-ties to prevent damage.
10.Refer to your echosounder owner’s manual to connect the sensor to
the instrument.
Antifouling Paint
Marine growth can accumulate rapidly on the sensor’s surface
reducing performance within weeks. Surfaces exposed to salt
water that do not interlock,
must
be coated with antifouling paint.
Use
water-based
antifouling paint only.
Never
use ketone based
paint, since ketones can attack many types of plastic possibly
causing damage to the transducer. Apply paint every 6 months or
at the beginning of each boating season.
AIRMAR
TECHNOLOGY CORPORATION
35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA
■
www.airmar.com
Figure 13. Servicing the speed sensor
side view
shaft
short side
of blade
insert shaft
Sensor Replacement
The information needed to order a replacement sensor is printed
on the cable tag.
Do not
remove this tag. When ordering, specify
the part number, date, and frequency in kHz.
4
Copyright 2000. All rights reserved.
BOW
through
hole B in
B
retaining
bar (2)
speed
sensor
housing
Checking for Leaks
Warning
: When the boat is placed in the water,
immediately
check for leaks around the screws and any holes drilled in the hull.
Never install a sensor and leave the boat in the water unchecked
for several days.
Maintenance
,
Repair,
& Parts
Clean the sensor with a soft cloth and mild household detergent. If
fouling occurs, use a stiff brush or putty knife to remove the growth
being careful
to avoid scratching the bottom of the transducer. In
severe cases, wet sand the sensor (and paddlewheel) with fine
grade wet/dry paper.
Servicing the Speed Sensor
If the paddlewheel becomes fouled or inoperable, it can be cleaned.
Remove the two screws from the speed sensor (see Figure 13).
Slide it upward to remove it from the transducer housing. Grasp the
two retaining bars and pull to access the shaft.
After cleaning, slide the paddlewheel onto the shaft.
Orient the
short side of the paddlewheel blade as shown on the side view.
It
must be oriented correctly to measure the boat’s speed. Fit the
shaft into the holes marked “B” in the retaining bars.
Note: There
is a left retaining bar marked with an L and a right retaining bar
marked with an R.
Slide the assembly into the speed sensor
housing.
Note: The interior of the housing is marked with a
corresponding L and R.
Re-attach the speed sensor.
Parts
Replace broken or worn parts immediately. The water-lubricated
paddlewheel bearings have a life of up to 5 years on low-speed
boats [less than 10kn (11MPH)] and 2 years on high-speed
vessels. Some depth/temperature units can be upgraded by
adding a speed sensor. Purchase parts from you marine dealer or
instrument manufacturer.
Part
Part Number
Paddlewheel Kit
33-473-01
Bracket and Wedge Kit
33-479-01
Speed Sensor Kit
33-346-03
