Your transducer sends a sonar signal through the water. Submerged equipment and hull features can generate turbulence that interferes with the sonar signal. You should install your transducer as far as possible from any equipment or hull features that can agitate the water to the degree that the sonar signal is lost or degraded.

Typically turbulence forms in the direction of the prop rotation (Direction of Propeller Rotation). Unavoidably vessels create turbulence while running, and knowing where turbulence tends to form can help you choose the best available mounting location for your transducer.