Simrad SN90 Purse seine and trawling sonar
Determining the location the transducer
A single answer to the question “where to install the transducer” cannot be given.
The physical location of the transducer depends on the vessel's design and construction, how the hull is shaped, and how the water runs along the hull. There are however a number of important
guidelines, and some of these are even conflicting.
The information here must be considered as general advice. Each transducer installation must be handled separately depending on the hull design.
Stay away from the propellers
The propulsion propellers is the dominant noise source on most vessels. The noise is transmitted through the sea water, and may often reduce the performance of your system.
For this reason, the transducer must be placed far away from the propellers, which means on the fore part of the hull. Positions outside the direct line of sight from the propellers are favourable.
On small vessels with short distances it is advised to mount the transducer on that side of the keel where the propeller blades move upwards, because the propeller cavitation is strongest on the other side. The cavitation starts most easily when the water flows in the same direction as the propeller blade, and that is to some degree the case at that side of the keel where the propeller blades move downwards.
(Photo: US Navy / Wikipedia)