Fishfinder and Sounder Module Transducer Introduction
Frequencies
Transducers are designed to work at different frequencies. Generally, higher frequencies are used in shallower water, and lower frequencies in deeper water. When you review the Fishfinder or Sounder Module data, you will see that they support 200 kHz for shallow water and 50 kHz, 38 kHz or 28 kHz for deep water. Lower frequency transducers cost more than higher frequency transducers.
Beam Angle
The transducer design also yields the beam angle. The wider the beam angle, the greater the amount of water covered by each ping. Greater beam angle lets you search more area for fish but also means lower resolution of the bottom profile directly beneath the boat. Higher resolution (lower beam angle) transducers are generally used in shallow water, and greater coverage (wide beam angle) transducers are generally used in deeper water.
Mounting
As mentioned, transducers can be mounted in several ways-
Transom Mount
Attaching the transducer directly to your boat’s transom is the most common method of mounting smaller transducers. Transom mount transducers can combine depth, speed and temperature sensors.
Through-Hull
There is a wide variety of high quality, high performance, and high power through hull transducers available, but they require that you drill a hole in your hull. If you are not comfortable doing this, get professional installation assistance. Through hull transducers can combine depth, speed and temperature sensors.
In Hull
Similar to through-hull, there is a wide variety of high quality, high performance, high power through in-hull transducers available. They don’t require a hole in your hull, but power is lost when the pulse travels through the hull. You must choose the in-hull location very carefully to minimize this loss. Again, if you are not comfortable doing this, get professional help. In-hull transducers can combine depth and temperature sensors, but not speed. Since many boaters obtain the speed reading from GPS anyway, this is usually not a concern.
Transducers come with very detailed installation instructions. Be careful to follow these directions carefully during the installation.
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