All of the parts of this system must be designed to work together, under any weather condition and extreme temperatures.
High transmitter power increases the probability that you will get a return echo in deep water or poor water conditions. It also lets you see fine detail, such as bait fish and structure.
The transducer must not only be able to withstand the high power from the transmitter, but it also has to convert the electrical power into sound energy with little loss in signal strength. At the other extreme, it has to be able to detect the smallest of echoes returning from deep water or tiny bait fish.
The receiver also has an extremely wide range of signals it has to deal with. It must dampen the extremely high transmit signal and amplify the small signals returning from the transducer. It also has to separate targets that are close together into distinct, separate impulses for the display.
The display must have high resolution (vertical pixels) and good contrast to be able to show all of the detail crisply and clearly. This allows fish arches and fine detail to be shown.
Factors to consider when selecting a transducer
When trying to determine which transducer is best for you, you’ll need to consider the following variables:
* What material the transducer housing is made of, based on boat hull composition
* How the transducer should be mounted on the boat: in the hull, through the hull, or on the transom
* What you want to see displayed: depth, speed, temperature, or a combination
The first step is to determine what material the transducer should be composed of.
Plastic housings are recommended for fiberglass or metal hulls.
Bronze housings are recommended for fiberglass or wood hulls. Bronze is preferable to plastic for wooden hulls because the expansion of wood could damage a plastic transducer and cause a leak. Installation of a bronze housing in a metal hull requires an insulating fairing. A metal housing should NOT be installed in a vessel with a positive ground system.
Stainless Steel housings are recommended for steel or aluminum hulls.
The accuracy with which your fishfinder detects bottom and other objects is also determined by the frequency selected for the depth you are viewing.
200kHz Echo Sounder Display in 50'(15m) of water
Better object separation and increase detail
200 kHz works best in water under 200 feet/60 meters and when you need to get an accurate reading while moving at faster speeds. High frequencies give you greater detail to detect very small objects but over a smaller portion of water. High frequencies typically show less noise and fewer undesired echoes while showing better target definition.
50 kHz Echo Sounder Display in 50' (15m) of water
Less detail but a wider viewing angle
For deep water, 50 kHz is preferred. This is because water absorbs sound waves at a slower rate for low frequencies and the signal can travel farther before becoming too weak to use. The beam angle is wider at low frequencies, meaning the outgoing pulse is spread out more and is better suited for viewing a larger area under the boat. However, this also means less target definition and separation and increased susceptibility to noise. Although low frequencies can see deeper, they may not give you a clear picture of the bottom.
A rule of thumb would be to use the 200 kHz setting for a detailed view to about 200 feet and then switch to 50 kHz when you want to look deeper. Better yet, display both views side-by-side on a split screen for both perspectives.