Garmin Fishfinder 100 - Manual (Page 39)

31
On the Water
Understanding the Chart
Whiteline
The Fishfinder 100 can help you to determine if the bottom is hard or
soft. When the sonar soundwaves are reflected back by the bottom, a hard
bottom will return a stronger signal than a soft bottom. The stronger
bottom return, the wider the bottom layer is displayed. The unit uses the
whiteline function to make this bottom layer information easier to
distinguish.
When viewing the display without Whiteline active, the bottom return
is black. While you can make some determination of the bottom type, the
black return makes this more difficult. With the whiteline active the
bottom return appears layered in shades of gray and black and makes
determining the bottom type easier and more reliable. Example 3 shows
the bottom return with and without the whiteline activated.
Whiteline Turned Off Whiteline Active
Hard
Bottom
Soft
Bottom
Whiteline
Example 3.
Whiteline can also help you to determine the
type of bottom structure that is displayed on
chart. By determining the hardness of the
structure you can make a better informed
decision on the type of structure.
Structure is hard,
probably a rock or stump Structure is soft,
probably a mud pile
100 On the Water.p65 2/16/00, 10:08 AM 31