Raymarine gS Series, Installation And Operation Instructions Manual, Page: 101 / 208

3. Select Rename .
The on-screen keyboard is displayed.
4. Enter the new name for the channel.
5. Select SAVE .
Deleting custom channels
With the Channel selection page displayed:
1. Select the tab for the sonar module that contains the channel
you want to delete.
2. Select the Channel options icon next to the custom channel.
3. Select Delete .
A confirmation dialog is displayed.
4. Select Yes .
The custom channel has now been removed from your system.
17.7 The sonar image
Interpreting the bottom using sonar
It is important to understand how to correctly interpret the bottom
structure represented on-screen.
The bottom usually produces a strong echo.
The following images show how different bottom conditions are
represented on-screen:
D
6
8
5
5
-3
1
2
3
Item Description
1 A hard bottom (sand) produces a thin line.
2 A soft bottom (mud or seaweed cover) produces a wide
line.
3 A rocky or uneven bottom or a wreck produces an irregular
image with peaks and troughs.
The dark layers indicate a good echo; the lighter areas indicate
weaker echoes. This could mean that the upper layer is soft
and therefore allowing sound waves to pass to the more solid
layer below.
It is also possible that the sound waves are making two complete
trips – hitting the bottom, bouncing off the vessel, then reflecting
off the bottom again. This can happen if the water is shallow or
the bottom is hard.
Factors influencing the sonar display
The quality and accuracy of the display can be influenced by a
number of factors including vessel speed, depth, object size,
background noise and transducer frequency.
Vessel speed
The shape of the target changes along with your speed. Slower
speeds return flatter, more horizontal marks. Higher speeds
cause the target to thicken and arch slightly, until at fast speeds
the mark resembles a double vertical line.
Target depth
The closer the target to the surface, the larger the mark on
screen.
Water depth
As water depth increases signal strength decreases, resulting in
a lighter onscreen image of the bottom.
Size of the target
The larger the target, the larger the return on the fishfinder
display. The size of a fish target is also dependent upon the size
of the fish’s swim bladder rather than its overall size. The swim
bladder varies in size between different breeds of fish.
Clutter / Background noise
The fishfinder picture may be impaired by echoes received from
floating or submerged debris, air bubbles or even the vessel's
movement. This is known as ‘Noise’ or ‘Clutter’ and is controlled
by the Sensitivity Settings. The system can automatically control
some settings according to depth and water conditions. You can
also adjust the settings manually if required.
Fishfinder application
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