Operation Manual

116 User Manual
Operating Frequency
Readout of the selected operating frequency.
6.2.1 UNDERSTANDING THE ECHOGRAM DISPLAY
The main elements that can be easily distinguished into an Echogram are:
White Line
5
3
Thermoclines
2
4
Surface Clutter
Structures
Fishes
1
6
Bottom Echo Profile
1
4
3
2
6
5
Fig. 6.2.1 - The Fish Finder echogram
Fishes
Fishes are represented as arcs because of the cone angle of the transducer. In fact as the
boat passes over the fish the leading edge of the cone strikes the fish, causing a display pixel
to be turned on. As the boat passes over the fish, the distance to the fish decreases turning
each pixel on at a shallower depth on the display. When the boat is directly over the fish, the
first half of the arch is formed and since the fish is closer to the boat, the signal is stronger
and the arch is thicker. As the boat moves away from the fish, the distance increases and the
pixels appear at progressively deeper depths forming the remaining half of the arch.
Thermoclines
Are the zones where two layers of different water temperatures meet. The greater the
temperature differential, the thicker the thermocline is shown on the screen.
Thermoclines are represented as horizontal stripes of noise. They are very important
for fishing since often many species of game fish like to suspend in, just above, or just
below the thermoclines.
White Line
The White Line shows the difference between hard, soft bottoms and even distinguishes
between fishes and structures located near the bottom. In this way it is easier to tell the
difference between a hard and soft bottom and even to distinguish fishes and structures
located nearby the bottom. For example, a soft, muddy or weedy bottom returns a
weaker echo that is shown with a narrow white line while a hard bottom returns a
strong echo that causes a wide white bottom line.