Using White Line; Adjusting Display Gain (Sensitivity) - Raymarine hsb2 PLUS Owner's Handbook Manual

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An uneven bottom which is covered with rocks or coral produces a complex
display; the bottom image is irregular, with long tails pointing upward. A
wreck produces a similar image.
A softer bottom or a bottom covered with seaweed produces a wide line, as the
sound waves reflect from different layers of the bottom. In Figure 4.2b, the
Fishfinder is getting a good echo from the bottom, so the upper layer of the
bottom is shown as dark gray.
Notice that the lower layer of the bottom is shown as a lighter gray, this
indicates a weaker echo. This could mean that the upper layer is soft; some
sound waves may get through this layer and be reflected as a more solid layer
below.
It is also possible that the sound waves are making two complete trips – hitting
the bottom, bouncing off the boat, then reflecting off the bottom again; this can
happen if the water is shallow, the bottom is hard, or gain is set high.

Using White Line

The White Line feature separates echoes from fish near the bottom and the
bottom itself. When the White Line is switched on, the Fishfinder displays the
echoes differently.
With color LCDs, the strongest echoes are displayed in the background color
with a thin line on top. All other echoes remain unchanged.
In the L755RC Plus monochrome LCD, the weakest echoes continue to be
displayed in the background color white, but colors for the other signal are
reversed. Thus, from the strongest to the second weakest the colors are: light
gray with a thin black line on top, dark gray, black.
➤ To switch the white line feature on and off:
MULTI
1. Press the MULTI key, the WHT LINE soft key is displayed.
WHT LINE
2. Press the WHT LINE soft key to toggle the white line feature ON or OFF.
OFF ON

Adjusting Display Gain (Sensitivity)

The fishfinder provides controls for GAIN, COLOR GAIN, and STC. These
controls, accessed from the GAIN key, are used to reduce background noise
and determine how different strength echoes are shown. Automatic
adjustment of GAIN or COLOR GAIN is available, alternatively you can
manually adjust any of these parameters using the trackpad and you can fine-
tune the auto-gain setting. You adjust gain for each transducer frequency
independently.
hsb Plus Series Fishfinders
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