Humminbird 150SX, Operation Manual

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Bottom. The graphic depiction of the bottom provides an effective tool
for understanding the composition of the bottom. If the bottom is hard
and smooth, the bottom depiction is narrow and dense. If the bottom is
soft mud or sand, the depiction will be thick and less dense. This indicates
much of the signal is absorbed by the soft bottom. If the bottom is rocky
or rugged in composition, the depiction is of varying density and textured
in appearance.
Wave action also affects the bottom
depiction. The information drawn is
a distance measurement, so if the
boat is moving up and down over flat
bottom, the bottom depiction often
appears in regular variations that
match wave timing.
Structure. Structure is defined as any
object physically attached to the
bottom. The sonar configuration of
the 150SX is optimized to give the
most accurate depiction of bottom
structure possible. Grass, trees,
stumps, wrecks or other debris are
accurately displayed, however the
depiction of these objects varies with
boat speed and direction. The best way to learn to interpret structure is to
operate the 150SX over a variety of known conditions and experiment with
user functions to best represent those conditions on-screen.
Surface Clutter. Surface clutter is the layer of water near the surface that
is rich in algae and other growth, and often is aerated by wind or wave
action. This area of water interferes with sonar transmission and often
appears on-screen as regular clusters of individual dots near the “0” line.
Thermoclines. Thermoclines are sharp differences in water temperature.
These are easily identified by the continuous nature of the return.
Second Returns. When a sonar signal is reflected off the bottom back to
9
USING THE 150SX
WHAT YOU SEE ON-SCREEN
Surface Clutter Rocky Bottom
Soft Bottom Hard Bottom