Topic 16 - How to read a fish finder screen

Returning echoes from the water below will show fish schools, the seabed and plankton in color on the fish finder screen. However, what is actually shown on the fish finder screen is not real images of these fish schools and plankton. The image on the fish finder screen is the result of the returning echoes coming from the seabed that pass through the transducer, through the reception processing and image processing circuitry of the fish finder and then finally to the screen. Depending on the echo strength, the color on the screen changes accordingly, the stronger the echo the deeper the color.

In previous chapters, information on the fish finder screen has been discussed, but not how the fish finder screen looks when in motion. The echoes coming from the fish schools below are displayed according to the time received by the fish finder in a sequential manner. The incoming signals are displayed sequentially scrolling from the right side of the screen to the left. The right side displays what the fish finder sees in that instant, and this data scrolls to the left.

The data on screen is purposefully moving at a constant speed, scrolling from the right to the left. The scrolling speed can be easily changed, making it easy for the user to find a comfortable setting. When the scrolling speed is set to high, even a small fish school will show up as a large echo on the fish finder screen.