Simrad SH40
Layers and deflections
Your sonar operations may also be disturbed by environmental
situations that you are unable to control. Two typical conditions
are temperature and salinity layers, and deflections caused by
increasing or decreasing water temperature.
Temperature and salinity layers
You may experience that temperature and/or salinity layers exist
in the water column. Since the speed of sound in water depends
on its temperature and salinity, such layers will cause the sound
beam to be reflected.
B
(CD015005F)
A
If you transmit a sonar beam down towards a temperature
or salinity layer (A), it will be reflected as indicated in the
illustration. The school of fish (B) you thought you would see
will not be visible at all.
Deflections
On warm days — especially during summer — the sea surface
will be heated by the sun, and the water temperature will
gradually decrease with increasing depth.
(CD015005G)
B
A
When the temperature decreases (A) closer to the bottom, the
sonar beam is deflected down as indicated by the illustration. The
school of fish (B) you thought you would see is not visible at all.
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302656/A
