Furuno CI-68 - Manual (Page 19)

1. OPERATIONAL OVERVIEW
1-9
1.6 Choosing Speed Tracking Mode
The tracking mode is available in ground tracking, water tracking, NAV and automatic.
Ground tracking:
Absolute ship and tide movements based on ground and current (tide
display (bottom echo must be present).
Water tracking:
Ship and tide movements relative to near-surface water and tide
differential between tide layers. (The pulse length in this mode must be
NORMAL and depth greater than 40 m, or LONG pulse length and depth
greater than 70 m.)
Nav:
Ship’s movement as measured by a navigation device and tide
movements based on nav speed data.
Auto/external*:
Uses ground tracking mode when bottom echo is available and switches
to water tracking mode (or Nav mode) when bottom echo is lost. The
bottom echo is continuously sought, and if re-acquired the ground
tracking mode is restored. *EXT appears in the tracking mode window
(top left corner) when DEPTH MODE in the OTHER menu (sub menu in
the installation menu) is set to EXTERNAL.
To choose the tracking mode, press the [TRACK MODE] key. The tracking mode changes
according to the setting (OFF or ON) of NAV MODE in the MENU 1 menu. The current
tracking mode appears at the top left-hand corner on the screen.
OFF:
The tracking mode changes cyclically in the sequence of ground tracking, water
tracking and auto.
ON: The tracking mode changes cyclically in the sequence of ground tracking, nav and
auto.
Bottom
Ship's movement
based on ground
Dir
N
Layer 1
Measuring
depth
Tide movement
of layer 1
Speed
Layer 2
Layer 3
Tide movement
of layer 2
Tide movement
of layer 3
Layer 1
Tide movement of
layer 1 relative to
surface water
Layer 2
Layer 3
Tide movement of
layer 2 relative to
surface water
Tide movement of
layer 3 relative to
surface water
Ship's movement
relative to surface
water
Surface Layer
(Reference layer)
Ground Tracking Mode Water Tracking Mode Nav Mode
Layer 1
Tide movement
of layer 1
Layer 2
Layer 3
Tide movement
of layer 2
Tide movement
of layer 3
GPS Satellies
Ship's movement
measured by
using satellites
(Based on ground)
Tracking modes