JRC JMA-9922-9XA - Page 57

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Vo:
O\rm ship's speed
0
o:
Own ship's course
Vr:Other ship's lrue speed
Vr: Other
ship's
reative
speed
I
r:
Olher ship's tue couse
6
":
Other ship
s
realive
couse
0
A:Asp€ct
Fi9.1.21
Relative Vector and True
Vector
Radarand Gollision
Avoidancg'''''
r'
r''
r'''''''
r''
Radar
is
still
playing
an
important
roll for
collision
prevention
and
positioning.
A
plotter
is
used to
further enhance
the radar functionality. The
plotter
is capable
of
plotting
other
positions
of other
ships
in
3 to 6 minute intervals
to monitor
their movements. The
plots
of other ships
represent their tracks relative to own ship,
and
it is shown whether
there
is a there is a
risk
of collision, namely
CPA and
TCPA can
be obtained. This method
using
a
plotter
is
fairly effective,
but the number of target
ships, which
are
manually
plotted,
is limited and
it
takes several minutes to measure those
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