Onwa Marine Electronics KR-12X8 - Manual (Page 75)

COURSE/SPEED (Course/Speed):
Course and speed are displayed for the lastplotted or selected target with suffix
"T"(Ture) or "M"(Magnetic). For true bearings suffix "T"is used in case of gyroc-
ompass input and suffix "M"is used in case of magnetic compass input.
CPA (Closest Point of Approach) is the closest range a target will approach to own
ship. Do not mix it with the operator preset CPA alarm limit.
TCPA is the time to CPA measured with present speeds of own ship and the targets.
Both CPA and TCPA are automatically calculated. When a target ship has passed
clear of own shop, the CPA is displayed and the TCPA appears as "**". TCPA
is counted up to 99.9 min. And beyond this it is indicated as TCPA>99.9 min.
Mode and length of Vectors
Ture or Relative Vector
Target vectors are displayed in relative or true mode. Own shop does not have a
vector in relative mode.
Vector Length
From the ARPA MENU, Vector Length can be set to 30 seconds,1,3,6,15 or 30
minutes and the selected vector time is indicated on the screen.
The vector tip shows an estimated position of the target after the selected vector
time elapses. It can be valuable to extend the vector length to evaluate the risk of
collision with any target.
Past position Display
The Auto Plotter displays equally time-spaced dots(maximum 5 dots) marking the
past positions of any targets being tracked.
If a target changes its speed, the spacing will be uneven. If it changes the course,
its plotted course will not be a straight line in TM mode.
Operational Warnings
There are two main situations which cause the Auto plotter to trigger visual and
audible alarms.
CPA/TCPA alarm
Lost target alarm
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