Vexilar LC-507 - Manual (Page 23)

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DEAD ZONE
Dead Zone is the area within
the transducers cone that is blind
to you. The wider 107 kHz beam
will have a much larger dead
zone than the narrow 400 kHz
beam. The LC-507 will mark bot-
tom as the nearest distance it
sees. If you are fishing over a
slope, it may see the high side of
the slope, at the edge of the cone,
and mark that as bottom. The
fish that are hanging on the bot-
tom in the center of the cone will
be invisible to you because they
are actually within the bottom
signal on your depth finder. A
narrower beam angle will reduce this effect.
The Clean Line feature can, also, allow you to see inside the dead
zone. If it is properly adjusted, you can see fish arcs within the
“cleaned out” section of the bottom. The further down into the bot-
tom signal they appear, the farther away from the boat they are.
SURFACE CLUTTER
The line of information going across the top of the display rep-
resents the surface of the water. This line can get quite wide, at times,
due to surface clutter. Tiny marine life, such as algae or plankton,
can be responsible for this. Choppy or rough waters can also be a
cause as tiny air bubbles are forced down under the surface. Surface
clutter has little effect on the performance of the unit. It can, how-
ever, make things difficult to see in shallow water. The 107 kHz beam
will be more likely to display this clutter than the 400 kHz beam.
Figure 27