Furuno MODEL CSH-73 - Manual (Page 19)

2-3
Selecting a Display Range
Operate the RANGE control to select a display range. The range
selected appears at the top center of the screen.
Setting the Tilt Angle
The tilt angle shows the direction to which the sound wave is
emitted. When the sound wave is emitted horizontally, the tilt
angle is said to be zero degrees and when emitted vertically, 90
degrees.
To set a tilt angle, operate the TILT lever.
Watch the tilt angle indication at the top right
corner on the screen. The tilt angle can be set
in one-degree steps from 0 to 90 degrees.
Finding a proper tilt angle is important when searching for fish.
The beam of the half-circle scanning sonar is fan shaped as in
(A) below and it swings up and down according to the setting of
the TILT lever. If you look at the angle between the horizontal
plane (sea surface) and several points on the beam, it can be
seen that the angle is maximum in the center of the beam (q) and
becomes smaller as it goes toward the edge, finally becoming
zero degrees at the edge of the beam. This will be more clearly
understood if you look at a vertically directed beam. See (B)
below. You should keep in mind that the tilt angle displayed on
the screen is the angle the center of the beam forms with the
horizontal plane.
θ
SEA SURFACE
(A) (B)
Figure 2-1 Tilt angle
R400
T 15 Tilt
angle