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Transducer Selection

Nearly every boat sold today has one or more fishfinder or instrument transducers installed. Some installations are carried out by the factory, but most are done by a professional installer or the boat owner.

Transducers can be mounted in a number of different locations on the boat, and the shape of the boat's hull and the placement of its engines have to be taken into account when choosing a transducer type that will deliver optimal performance for the vessel.


1. Great depth performance starts with optimum transducer placement.

2. Transducers function as both antenna and microphone for the depth sounder. Installation dictates the quality of both the send and receive signals.

3. The sonar portion of a transducer consists of a ceramic element precisely wrapped in layers of cork and metallic shielding. It is encapsulated in an acoustic watertight material.

4. Clean water flow over the face of the transducer is critical to the proper operation of the system and is the single most important parameter in selecting a mounting location.

5. Transducer Selection Steps : First, select the best mounting style for your boat from the options shown here. Second, select the best location. Third, select the best frequencies.

6. Transom models are for displacement or planing hulls with single or twin inboard/outboard, outboard, and jet drive systems.

7. Transom models are simple to install.

8. In-hull models work with solid fiberglass (uncored) hulls but do not have a water temperature sensor.

9. Tilted through-hull low-profile models compensate for hull deadrise.

10. Some through-hull models have an external fairing that can be cut to compensate for deadrise.

11. The external fairing helps control water flow over the transducer.

12. Fairings should be cut at an angle to match the hull deadrise, with the two parts mounted both inside and outside the hull to ensure that the beam faces directly down.