Airmar P23 - Manual (Page 3)

Mounting & Adjusting
CAUTION: Do not position the leading edge of the sensor lower
than the trailing edge because aeration will occur.
CAUTION: Do not position the sensor farther into the water than
necessary to avoid increasing drag, spray, and water noise and
reducing boat speed.
1. Align the posts on the shim with the two holes in the bracket. Snap
the shim into place.
High-speed operation [above 35kn (40MPH)]—It may be
necessary to install the bracket with both shims to ensures that
the paddlewheel will be in contact with the water at high speeds.
Remove the posts from the 4.5 degree shim with wire cutters.
Place the 4.5 degree shim, taper down, behind the 9 degree shim.
2. Apply a marine sealant to the threads of the two #10 x 1-1/4"
self-tapping bracket screws to prevent water seepage into the
transom. With the shim(s) in place, screw the bracket to the
hull. Do not tighten the screws completely at this time.
3. Using a straight edge, sight the underside of the sensor relative
to the underside of the hull (see Figure 5). The trailing edge of
the sensor should be 1–3mm (1/16–1/8") below the leading
edge of the sensor or parallel to the bottom of the hull.
4. Using the vertical adjustment space in the bracket slots, slide
the sensor up or down until the bottom left corner of the sensor
projections 3mm (1/8") below the bottom of the hull (see
Figure 6). When you are satisfied with the position of the
sensor, tighten the screws.
Testing on the Water
1. Become familiar with your echosounder’s performance at a
speed of 4kn (5MPH).
2. Gradually increase the boat speed and observe the gradual
decline in performance due to turbulent water flowing over the
transducer’s active surface.
3. If the decline in performance 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 to the side on which
the sensor is installed, its position probably needs adjustment.
It is probably in aerated water.
To improve performance, try the following one at a time in the
order given.
A. Move the multisensor farther into the water in increments of
3mm (1/8") (see Figure 4).
B. High-speed operation above 35kn (40MPH) may be
improved by less projection in the water. Move the sensor
upward on the transom.
C.Increase the multisensor’s angle in the water. Install the 4.5•
shim with the taper down (see Figure 5).
D.Move the multisensor closer to the centerline of the boat. Fill
unused screw holes with marine sealant.
Cable Routing
CAUTION: Do not remove the connector 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.
Route the sensor cable over the transom, through a drain hole or
through a new hole drilled in the transom above the waterline.
1. If a hole must be drilled through the transom, choose a location
well above the waterline (see Figure 6). 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 one 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 screw 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.
Checking for Leaks
When the boat is placed in the water, immediately check for
leaks around the screws and any holes drilled in the hull. Note
that very small leaks may not be readily observed. Do not leave
the boat in the water unchecked for more than three hours.
3
Figure 6. Vertical adjustment and cable routing
50mm (2")
cable cover
cable clamp
Hull projection:
3mm (1/8")
AIRMAR ®