BASIC ELECTRONICS 5
For some, interpreting a fish finder’s screen can be very challenging. Here is advice on how to make sense of what you see.
Sonar measures distance using time. The best way to describe it is; the fish finder’s screen is just turning lights on and off, depending on how far the object is from the transducer and the time it was in contact with the transducer to measure that distance.
Those imagesg can be the bottom, structure, an object close to the bottom and now and then it will be something swimming or drifting in the water column.
If you are not an experienced fish finder reader it can beb slightly difficult to read the displayed images. To see theth typical fish arches the boat has to move slowly over theth fish. Why the fish appears like arches on the screen is th the most asked question. It’s all about the interaction time be between the transducer and the fish. As soon as the fish comesco in contact with the outer edge of the transducer’s signalsig the screen will be activated. At the same time as the fish moves nearer to the centre line, the distance between the transducer and the fish decreases.
Th The decrease in the distance will cause the line to curve. As t the fish arrive directly at the centreline of the cone the first fififirst half of the fish arch is done. When the fish move away from the centre line the pixels will complete the second halfhal of the arch.
Something to remember: if the boat is not moving the fififififififish fish will show as a horizontal line. When fish are moving thro through the centre line of the transducer’s cone, the arch will not be as distinct.
Th The length of the arch has not anything to do with size of the fish. Long arches is only showing the time it took to move towards,t or over the object it has picked up, based upon y your horizontal speed. If you understand this you will be fine.
To sees the sizes of the fish you have to look at the top (centre) of the arch. Big fish will appear with a wide centre and vice versa, (smaller fish - narrow centre). Generally we think all arches are fish. Yes it can be, but it can probably