Airmar TM185HW Technical Document

17-299-02 rev. 05 06/02/15
Transom Mount, 1kW with Short Release Bracket
Depth Transducer
with Temperature Sensor
Models: TM185HW, TM185M, TM258, TM260, TM265LH,
TM265LM, TM270W, TM275LHW
U.S. Patent No. 7,369,45; 8,582,393. UK Patent No. 2 414 077
Tools & Materials
Safety goggles
Dust mask
Angle finder
Masking tape (some installations)
Pencil
Electric drill
Drill bits and hole saws:
Bracket holes 5mm, #4, or 7/32"
Transom hole (optional) 18mm, 11/16", or 3/4"
21mm or 13/16" (Furuno, Raymarine only)
Cable clamp holes 3mm or 1/8"
Marine sealant (suitable for below waterline)
Socket wrench
Straight edge
Small screwdriver
Grommet(s) (some installations)
Cable ties
Water-based anti-fouling paint (mandatory in salt water)
Applications
• Recommended for outboard and inboard/outboard sport fishing
powerboats 8m (25') and up
• Not recommended for inboard powerboats
• Not recommended for stepped hulls
• Adjusts to transom angles from 3°–21°
• Bracket protects transducer from frontal impact only
Mounting Location
Guidelines
CAUTION: Do not mount the transducer in line with or near water
intake or discharge openings or behind strakes, fittings, or hull
irregularities that may disturb the water flow.
CAUTION: Avoid mounting the transducer where the boat may be
supported during trailering, launching, hauling, or storage.
• For best performance, the transducer’s face must be in contact
with smooth water. To identify an area of “clean” water, observe
the flow off the transom while the boat is underway.
• Allow space above the bracket for it to release and rotate the
transducer upward.
• Mounting on the side of the transom where the propeller blades
are moving downward is preferred (see Figure 1).
• Mount the transducer as close to the centerline (keel) of the
boat as possible to ensure the transducer’s face remains in the
water when the boat is turning. However, be sure it is a
minimum of 15 cm (6") beyond the swing radius of the propeller,
so the water passing under the transducer does not cause a
flow disturbance to the propeller.
Record the information found on the cable tag for future reference.
Part No.________________ Date___________ Frequency________ kHz
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 goggles and a dust
mask when installing.
WARNING: When the boat is placed in the water,
immediately check for leaks around the screws and
any other holes drilled in the hull.
CAUTION: CHIRP transducer—Always operate the
transducer in water. Operating in air will allow the
transducer to overheat resulting in failure.
CAUTION: Never pull, carry, or hold the transducer by
the cable as this may sever internal connections.
CAUTION: Never strike the transducer to release it.
When mounted on the bracket, remove the transducer
by removing the locking pin and hinge pin.
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:Please read the instructions completely
before proceeding with the installation. These
instructions supersede any other instructions in your
instrument manual if they differ.
Figure 1. Mounting location on single drive boat
15cm (6")
minimum beyond
swing radius
NOTE: Starboard
side of hull where
propeller blades
are moving down-
ward is preferred.
Copyright © 2009 - 2010 Airmar Technology Corp.
hull projection
0–3mm (0–1/8")
parallel to
waterline
TM260
bracket with shims
operational position
INSTALLATION INSTRUCTIONSOWNER’ S GUIDE &

Figure 2. Stepped transom space requirement
TM185HW, TM185M, TM258: 244mm (9-3/4")
Boat Types
•Single drive—Mount a minimum of 15cm (6") beyond the
swing radius of the propeller (see Figure 1).
•Twin drive—Mount between the drives a minimum of 15cm
(6") beyond the swing radius of the propeller.
•Trim tabs—Mount inside the trim tab, space permitting.
•Stepped transom—Mount the transducer on the lowest step
being sure there is enough space above the bracket for it to
release and rotate the transducer upward (see Figure 2).
Installation
Assembling the Transducer & Bracket
1. Thread the cable through the large hole in the transducer
support (see Figure 3).
2. Fasten the support to the transducer using the three socket-
head-cap screws and washers supplied. Tighten the screws
with the 3/16" Allen wrench supplied.
3. Attach a safety ring to one end of each pin (see Figure 4).
4. While holding the transducer assembly against the bracket, insert
a pin through the upper hole in the bracket and the support.
Slide the spacer onto the pin and push it through the remaining
hole in the support and the bracket. Attach a second safety ring.
This pin will function as a hinge when the transducer is released.
5. Slide a washer onto the remaining pin. Push it through the
lower hole in the bracket, slide it along the channel in the
support, and through the second hole in the bracket. Slide the
second washer onto the free end of the pin and attach the
second safety ring. This will function as the locking pin to hold
the transducer in the operational position when underway.
Compensating for Transom Angle: Shims
For the best performance, the transducer beam must be aimed
straight at the bottom. Since the transom of most boats is angled,
the bracket must compensate for it. Measure the transom angle of
the boat with an angle finder.
•Standard transom (12° transom angle)—The bracket is
designed for a standard 12° transom angle. No shim is needed
for this installation. If your boat is capable of speeds above
20kn (28MPH), install the bracket with one 3° shim, taper
down. This will ensure that the transducer is in contact with the
water at high speeds.
•Using shims—The bracket is supplied with three shims; each
one has a 3° angle. Up to three shims can be combined for a
maximum of 9°. The shims are designed to mate together. Two
bosses on the face fit into recesses in the back of another shim or
the holes in the bracket.
-Transom angles greater than 12°—Add the appropriate
number of shims with the taper up to the 12° bracket angle.
-Transom angles less than 12°—To reduce the bracket’s
12° angle, group the appropriate number of shims with the
taper down.
•If you are unsure about using the shim(s), experiment with
the them by following the instructions “Mounting & Adjusting the
Bracket.”
Hole Drilling
CAUTION: To prevent drilling too deeply, wrap masking tape
around the bit 22mm (7/8") from the point.
NOTE: Fiberglass hull—Minimize surface cracking by running the
drill in reverse until the gelcoat is penetrated.
1. At the selected mounting location, position the assembly so the
transducer projects 3mm (1/8") below the bottom edge of the
transom (see Figure 1). Be sure any shim(s) is in place. (You
may want to tape the shim(s) to the bracket temporarily.) With
the transducer in the operational position, mark the bottom
corners of the bracket.
2. Remove the transducer assembly from the bracket by removing
the locking pin and the hinge pin (see Figure 4). Hold the
bracket with any shim(s) in place against the transom at the
marked location. Draw an “X” at 12mm (1/2") from the top and
the bottom of each slot (see Figure 6).
3. Using a 5mm, #4, or 7/32" drill bit, drill four holes 22mm (7/8")
deep at the marked locations.
2
Figure 3. Assembling the transducer
Copyright © 2009 Airmar Technology Corp.
Copyright © 2009 - 2014 Airmar Technology Corp.
TM260, TM265, TM275LHW: 260mm (10-1/4")
TM270W: 260mm (10-1/4")
bracket
support
transducer
hinge
locking
spacer
safety
Copyright © 2009 Airmar Technology Corp.
Figure 4. Attaching the transducer to the bracket
screw (3)
washer (3)
support
transducer
cable
washer (2)
pin
pin
ring (4)
detail
channel

Mounting & Adjusting the Bracket
CAUTION: Do not position the leading edge of the transducer
lower than the trailing edge because aeration will occur.
CAUTION: Do not position the transducer deeper in the water
than necessary to avoid increasing drag, spray, and water noise
and reducing boat speed.
CAUTION: The stainless steel bracket must be isolated from a
metal hull to prevent electrolytic corrosion. If no shim is being
used, place non-metal insulating washers between the bracket
and the metal hull.
1. Apply marine sealant to the threads of four of the hex-washer-
head screws to prevent water seepage into the transom. Being
sure any shim(s) is in place, screw the bracket to the hull using
a socket wrench (see Figure 4). Do not tighten the screws at this
time.
2. Reinstall the transducer. While holding the transducer assembly
against the bracket, insert the hinge pin through the upper hole
in the bracket and the support. Slide the spacer onto the pin
and push it through the remaining hole in the support and the
bracket. Reattach the safety ring.
3. Slide a washer onto the locking pin. Push it through the lower
hole in the bracket, slide it along the channel in the support, and
through the second hole in the bracket. Slide the second
washer onto the free end of the pin and reattach the safety ring.
4. With the transducer in the operational position, Use a straight edge
to sight the underside of the transducer relative to the underside of
the hull (see Figure 5). The trailing edge of the transducer should
be 1–6mm (1/16 –1/4") below the leading edge.
5. Using the vertical adjustment space in the bracket slots, slide the
assembly up or down until the bottom inside corner of the
transducer projections 0–3mm (0–1/8") below the bottom of the
hull (see Figure 1). When you are satisfied with the position of the
transducer, tighten the four bracket screws. For clear access to
the screws, remove the transducer assembly from the bracket
(see Figure 4). When reattaching, be sure to include the spacer.
Testing on the Water
1. Test the transducer at 200kHz with the engine off.
2. Become familiar with your echosounder’s performance at a
speed of 4kn (5 MPH).
3. Gradually increase the boat speed and observe the gradual
decline of performance due to turbulent water flowing under the
transducer’s face.
NOTE: As the speed increases the performance at 50kHz will
deteriorate more rapidly because more acoustic noise is
generated at low frequencies.
4. 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.
5. If the performance improves while turning to the side on which the
transducer is installed, it’s position probably needs adjustment.
The transducer is probably in turbulent or aerated water.
To improve performance, try the following, one at a time,
in the order given.
a. Increase the transducer’s angle in the water. Review
“Compensating for Transom Angle: Shims” and see Figure 5.
b. Move the transducer deeper into the water in increments of
3mm (1/8") (see Figure 1).
c. Move the transducer closer to the centerline of the boat.
Fill unused screw holes with marine sealant.
6. 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.
Stabilizing the Bracket
1. Prevent the bracket from moving out of position using the
remaining hex-washer-head screw. Drill the hole for the
stabilizing screw through the center hole of the bracket, any
shim(s), and the hull (see Figure 6). 3
12°transom angle 13°transom angle
Figure 5. Adjusting the transducer angle
21°transom angle9°transom angle
parallel slight angle
one shim
three shims
taper down
slight angle
parallel
one shim
taper down
parallel
May improve operation
above 20 kn (23MPH)
May improve operation
above 20kn (23MPH)
slight angle
two shims
taper down
slight angle
May improve operation
above 20kn (23MPH)
May improve operation
above 20kn (23MPH)
one shim
taper down
more angle
Copyright © 2009 Airmar Technology Corp.
Figure 6. Screw locations on bracket
screw (4)
stabilizing screw
Copyright © 2009 Airmar Technology Corp.
NOTE: Draw an “X” at
21mm (1/2") from the
top and bottom of
both slots.
taper up
two shims
taper up
hole (2) mate
with bosses
on shim

4Copyright © 2009 - 2015 Airmar Technology Corp. All rights reserved.
2. Apply sealant to the threads of the remaining screw to prevent
water seeping into the transom.
3. Fasten the stabilizing screw into place with a socket wrench.
For clear access to the screw, remove the transducer assembly
from the bracket (see Figure 4). When reattaching the
transducer, be sure to include the spacer.
Cable Routing & Connecting
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 cable over the transom for a detachable installation. For
permanent mounting, route the cable 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 7). Check for obstructions
such as trim tabs, pumps, or wiring inside the hull. Mark the
location with a pencil. Drill the 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 30cm (12")
above the bracket. 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 through the transom, open the large
slot in the transom 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.
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. Use grommet(s) to prevent chafing. To reduce
electrical interference, separate the transducer cable from other
electrical wiring and the engine(s). Coil any excess cable and
secure it in place with cable ties to prevent damage.
10.Refer to your echosounder owner’s manual to connect the
transducer to the instrument.
Checking for Leaks
When the boat is placed in the water, immediately check for
leaks around the screws and any other 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.
Maintenance
Anti-fouling Paint
CAUTION: Do not paint the exposed temperature button. Doing
so will slow the sensor’s response time.
Aquatic growth can accumulate rapidly on the transducer’s face
reducing performance within weeks. Surfaces exposed to salt
water that do not interlock must be coated with anti-fouling paint.
Use water-based anti-fouling paint only. Never use ketone-based
paint, since ketones can attack many types of plastic possibly
damaging the transducer. Repaint every 6 months or at the
beginning of each boating season.
Cleaning
CAUTION: Do not use a lubricant on the bracket; grit will stick to
it, increasing friction and wear.
Clean the sensor with a Scotch-Brite® scour pad and mild
household detergent, taking care to avoid making scratches on
the transducer’s face. If the fouling is severe, lightly wet sand with
fine grade wet/dry paper.
Transducer Replacement & Parts
The information needed to order a replacement transducer 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, and worn parts should be replaced immediately.
Bracket Assembly 33-749-01
Obtain parts from your instrument manufacturer or marine dealer.
Gemeco Tel: [phone]
(USA) Fax: [phone]
email: [email protected]
Airmar EMEA Tel: [phone]
(Europe, Middle East, Africa) Fax: [phone]
email: [email protected]
Figure 7. Cable routing
30cm (12")
cable cover
cable clamp
Copyright © 2009 Airmar Technology Corp.
35 Meadowbrook Drive, Milford, New Hampshire 03055-4613, USA
•www.airmar.com