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17-299-02 rev. 01 01/09
Transom Mount, 1kW, Depth Transducer
with Release Bracket
Models: TM258, TM260, TM270W
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 the transducer from frontal impact only
Tools & Materials
Safety goggles
Dust mask
Angle finder
Masking tape (some installations)
Pencil
Electric drill
Drill bits:
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
Grommets (some installations)
Cable ties
Water-based anti-fouling paint (mandatory in salt water)
Mounting Location
General Guidelines
CAUTION: Do not mount the transducer in an area of turbulence
or bubbles: near water intake or discharge openings; behind
strakes, struts, fittings, or hull irregularities.
CAUTION: Avoid mounting the transducer where the boat may be
supported during trailering, launching, hauling, or storage.
• For best performance, the transducer must be in contact with aera-
tion-free and turbulence-free water. To identify an area of smooth
water, observe the flow off the transom while the boat is underway.
• Allow headroom 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, keep in mind that it
should be a minimum of 15 cm (6") beyond the swing radius of
the propeller, so the water passing over 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
INSTALLATION INSTRUCTIONSOWNER ’S GUIDE &
WARNING: Always wear safety goggles and a dust
mask when installing to avoid personal injury.
CAUTION: Never pull, carry, or hold the transducer by
the cable as this may sever internal connections.
CAUTION: Do not 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. Cleaners, fuel,
sealants, paint, and other products may contain strong
solvents, such as acetone, which attack many
plastics, greatly reducing their strength.
IMPORTANT: Please read the instructions completely
before proceeding with the installation. These
instructions supersede any other instructions in your
instrument manual if they differ.
TM260
with shims
in operational position
Figure 1. Mounting location on single drive boat
15cm (6")
minimum beyond
swing radius
NOTE: Starboard
side of hull where
propeller blades are
moving downward
is prefered.
Copyright © 2009 Airmar Technology Corp.
hull projection
0–3mm (0–1/8")
parallel to
waterline