"Prop-wash" is a term that we often hear from boaters when discussing the effects of moving water produced by a spinning propeller on an outboard or inboard/outboard powered boat. Generally, the context in which we hear the term is in regards to its effect on electronic fish finder or sonar transducers mounted on the transom of a boat. The turbulence of a propeller creates a massive amount of air bubbles and while in forward gear or in reverse, that turbulence could very well create temporary interference with the sounding of the transducer rendering it ineffective. While moving slowly in forward gear (trolling speed), the water might be said to 'boil" into the direction of the boat transom where the transducer is mounted. Oftentimes, this will not affect the sounding of your tranducer. In reverse, of course, this "boil" or "prop-wash" would naturally be moved fore by the propeller. In either case, "prop-wash" turbulence could create air bubbles around the transducer eliminating its effectiveness. This is normal and to be expected. Mounting a transducer on the transom of a boat is widely considered the ideal location for maximum effectiveness. Mounting a fishfinder transducer elsewhere, such as a "shoot-thru-the hull", most always accompanies a compromise and reduced performance.
"Prop-wash", while it might present a problem at slow speeds or in reverse, does not present a problem whatsoever at higher speeds. It should; therefore, not be considered as having an affect causing poorly performing electronic soundings while at speed. While a boat is moving forward at speed, the turbulence ("prop-wash") is jetted rearward (aft) away from the boat and would not be a factor to be considered as having a detrimental effect by creating turbulence around the transducer. The concept of "prop-wash" and it's effect on sonar transducers is oftentimes misinterpreted producing unfounded concern.
