Humminbird 200DX - Manual (Page 20)

USING THE 200DX USING THE 200DX
WHAT YOU SEE ON-SCREEN
When in Auto mode, the horizontal line at the top of the
screen is the “zero line,” representing the surface of the
water. Occasionally there is a gap in this line. This gap
indicates the unit is updating the display even if the bottom is
not visible on-screen or if the bottom information is not
changing.
New sonar information appears on the right side of the
graphic area of the display and moves to the left as new
information is displayed. The 200DX automatically selects the
appropriate depth range to show the depth of water beneath
the transducer. This range is selected so the bottom
representation is typically shown about 2/3 down the display.
Bottom. The graphic depiction or 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. It 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.