As sonar technology continues to advance, choices have widened as prices of most of the sonars come down. First developed with the intention of determining depth, the sonars have a greater ability in finding fish, scan for bottom obstructions and create under water maps. It does not matter if it is a simple portable fish finder or a commercial mapping system that has several tons in weight; all sonar devices operate the same. They have two parts namely the transducer and display/ processor. So a good fish finder will help with locating your fish so reading fish finder reviews can help you find the correct finder for your needs.
The transducers are both a sender and receiver. It is what s placed in water or adjacent to a water body.it emits acoustic signals with a characteristics waveform. The signal passes through the water at a specified speed ad is reflected back to the transducer at a different density with water. When part of the acoustic signal strikes an object it is reflected back and transmitted to the processor. The choice of transducer depends on a number of things as mentioned below.
For recreational and light commercial boats, the transducer’s frequency should be between 25-400 KHz although 50 and 200 are the most common. Lower frequencies about 50 KHz is excellent for displaying a wide area of the bottom especially in deep waters whereas high frequency is excellent for showing details in shallow waters.
Lower frequencies are preferred for salt water, as high frequencies will lose about half as much as half its penetrating power. Most fish finder transducers operate on a dual frequency. The lower frequencies search the wider areas in deep waters showing schools of fish while higher frequencies show details directly under your boat. Some transducers have the ability to shift back and forth between high and low frequencies. You can read more about fish finders and transducers on www.fishfinderguy.com
This is the second most important feature to consider when choosing a transducer. Transducer with a wide beam up to 50 degrees sees around a wide location. Increase for area decreases the resolution. This makes the beam better for searching for fish in a column and not detecting bottom details like breaks, contours and shallow holes.
A narrow beam will concentrate its energy on a section just below the boat. This means that it is excellent for looking for individual fish and observing the bottom structure in shallow waters. There is a co-relation between transducer frequency and width of beam. Usually the lower the frequency the wider the beam angle.
This power is quoted in watts just as any transmitter and audio receiver. In this case, more power does not necessary mean better. Too much power in shallow water is ineffective just as little power is in deep water. Shallow water requires units of between 100-200 watts while those needed in deep waters should be 1000 watts and more.
Some time back traditional transducers were made with bronze housing with a narrow stem and curious aerodynamics. Today the most fish finder transducers have strong plastic housings. The tough materials used today have more advantages than bronze because there is less corrosion and electrolysis.