Airmar TM256 Owner'S Manual & Installation Instructions Download Page 2

 

Type of Boat

 

 

Single drive

 

—Mount a minimum of 15cm (6") beyond the 

swing radius of the propeller (see Figure 1).

 

Twin drive

 

—Mount outside the drives a minimum of 15cm (6") 

beyond the swing radius of the propeller.

 

Trim tabs

 

—Mount inside the trim tab, space permitting.

 

Drive extension

 

—Mount as far to the side as is practical.

 

Swim platform

 

—If the platform interferes with the movement of 

the transducer, make a cutout to accommodate the transducer 
and/or shorten the support tube.

 

Stepped transom

 

—Mount the transducer on the transom 

above the step. Use a straight edge to position the underside of 
the transducer even with the underside of the transom (see 
Figure 3).

 

Shortening the Support Tube

 

WARNING

 

: The upper latch pin must be inserted through the 

 

topmost

 

 holes of the support tube for the transducer to release. 

Failure to pin the support tube through the topmost holes can 
result in damage to the bracket if it releases.

 

If the transducer assembly is too high for the selected mounting 
location, the support tube 

 

must

 

 be shortened.

1. Remove the upper latch pin. Slide the support tube out of the 

bracket (see Figure 4). 

2. The support tube can be shortened in 25mm (1") increments up 

to a maximum of 28cm (11"). Determine the amount to be 
shortened from the 

 

top

 

 of the tube. Draw a line against the bot-

tom edge of the chosen hole 

 

plumb

 

 with the row of holes. 

 

Do 

not cut the bottom of the support tube

 

 (see Figure 5).

 

Warning

 

: Always wear safety goggles and a dust mask.

 

3. Cut the 

 

top

 

 of the support tube to the desired length.

4. File and sand the cut edge to remove sharp edges and burrs.

5. Replace the support tube in the bracket. Secure it by sliding the 

upper latch pin through the 

 

topmost

 

 adjustment holes (see 

Figure 4).

 

The upper latch pin must be inserted through the 

topmost holes of the support tube for the transducer to release. 

 

Installation

 

Caution

 

: Never pull, carry, or hold the transducer by the cable as 

this may sever internal connections.

 

Assembling and Positioning

 

1. Thread the cable through the support tube (see Figure 4).

2. Using the 3 hex socket cap screws and a 3/8" wrench, attach 

the transducer to the mounting shoe. 

 

Do not tighten the center 

screw at this time

 

. The transducer angle will be adjusted later.

3. With the transducer in the “down” position, hold the transducer 

assembly at the selected location on the transom. Locate the 
bottom of the transducer about 0–3cm (0–1/8") below the 
bottom edge of the transom (see Figure 1).

4. Depending on the angle of your transom, the bracket may need 

a shim(s) for the transducer to clear the transom when it is 
raised and lowered (see Figure 4). Check for clearances with 
the transducer in the “up”, “down”, and “released” positions (see 
Figure 2). Experiment with the shim(s) provided until there is 
sufficient clearance while maintaining the transducer face 
parallel to the water surface. When you are satisfied with the 
mounting location, use a pencil to draw the outline of the 
mounting plate on the transom (see Figure 6).

 

Note: The bracket is factory pre-set to provide a vertical travel of 
77mm (3") between the “up” and “down” positions. The vertical 
travel can be adjusted by moving the 

 

lower

 

 latch pin to another 

set of adjustment holes.

 

Figure 3. Stepped transom

Figure 6. Mounting plate and screw locations 

 

correct

incorrect

 

hull

screw

reinforcement 
bolt hole (2)

 

Figure 4. TM256 assembly

 

upper latch pin

bracket

latch release line

latch lever

lower latch pin

transducer

hoist line

hinge pin

safety ring

mounting plate

support tube

mounting shoe

adjustment hole

cable

location (4)

 

Figure 5. Shorten support tube

 

immediately
below a hole,
plumb with the
row of holes

shim (2)

 

do not 

 

cut

bottom (with
small holes) 

(17 pairs)

cut top only,

screw recess (2)

 

2

 

Mounting

 

1. Separate the mounting plate from the bracket by removing one 

safety ring and withdrawing the hinge pin (see Figure 4).

2. Position the mounting plate on the transom over the pencil 

outline with the shim(s) in place. (To hold the shim(s) in place, 
tape it to the bracket.) 

 

Be sure

 

 the bracket is plumb with the 

waterline (see Figure 6).

 

Warning

 

: Always wear safety goggles and a dust mask.

 

3. Using a 4mm, #23 or 9/64" bit, drill four holes, 30mm (1-1/4") 

deep, at the selected location. 

 

Be sure

 

 the drill is oriented 

parallel to the keel and at right angles to the transom. Drill 
through any shim(s). 

 

Do not drill the holes for the 

reinforcement bolts at this time

 

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