Lowrance LCX-112C Operation Instructions Manual page 21

NOTE:
Some aluminum boats with strakes or ribs on the outside of the
hull create large amounts of turbulence at high speed. These boats
typically have large outboard motors capable of propelling the boat
at speeds faster than 35 mph. Typically, a good transom location on
aluminum boats is between the ribs closest to the engine.
3. The transducer should be installed with its face pointing straight
down, if possible. For shoot-thru applications: Many popular fishing
boat hulls have a flat keel pad that offers a good mounting surface. On
vee hulls, try to place the transducer where the deadrise is 10° or less.
Pad
Left, vee pad hull; right, vee hull. A pod style transducer is shown here,
but the principle is the same for Skimmers inside a hull.
4. If the transducer is mounted on the transom, make sure it doesn't
interfere with the trailer or hauling of the boat. Also, don't mount it
closer than approximately one foot from the engine's lower unit. This
will prevent cavitation (bubble) interference with propeller operation.
5. If possible, route the transducer cable away from other wiring on the
boat. Electrical noise from engine wiring, bilge pumps and aerators
can be displayed on the sonar's screen. Use caution when routing the
transducer cable around these wires.
CAUTION: Clamp the
transducer cable to transom
near the transducer. This will
help prevent the transducer
from entering the boat if it is
knocked off at high speed.
Good
location
Poor angle
Good location
Good and poor transducer locations.
Deadrise less than 10°
Strakes
Good location
Poor location
11