Furuno 1942 MARK-2 - Manual (Page 42)

6-6
6.5 Mode and Length of
Vectors
True or relative vector
(vector mode)
Target vectors are displayed relative to own
ships reading (Relative) or with reference to
North (True). Own ship does not have a vec-
tor in relative mode.
Vector length
From the ARP-10 MENU, Vector Length can
be set to 30 seconds, 1, 3, 6, 15 or 30 min-
utes 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 vec-
tor length to evaluate the risk of collision with
any target.
6.6 Past Position Display
The Auto Plotter displays equally time-spaced
dots (maximum five dots) marking the past
positions of any targets being tracked.
If a target changes its speed, the spacing will
be uneven. If it changes course, its plotted
course will not be a straight line in TM mode.
To turn past position display an or off do the
following:
1. Open the ARP-10 menu.
2. Select History.
3. Select plot enterval among 15, 30 sec-
onds, 1, 2, 3 or 6 minutes. Select OFF to
erose the past position display.
4. Press the [ACQ/ENTER] key.
5. Press the [MENU] key.
6.7 Operational Warnings
There are two main situations which cause
the ARP-10 to trigger visual and audible
alarms:
CPA/TCPA alarm
Lost target alarm
CPA/TCPA alarm
The CPA/TCPA alarm feature should
never be relied upon as a sole means for
detecting the risk of collision.
The navigator is not relieved of the
responsibility to keep visual lookout for
avoiding collisions, whether or not the
radar or other plotting aid is in use.
CAUTION
Visual and audible alarm are generated when
the predicted CP A and TCP A of any target
become less than their preset limits. The au-
dible alarm continues for 10 seconds.
The ARP-10 continuously monitors the pre-
dicted range at the Closest Point of Approach
(CPA) and predicted time to CPA (TCPA) of
each tracked target to own ship.
When the predicted CP A of any target be-
comes smaller than a preset CPA alarm range
and its predicted TCPA less than a preset
TCPA alarm limit, the ARP-10 releases an
audible alarm. In addition, the target plot sym-
bol changes to a triangle and flashes together
with its vector. The flashing of the triangle plot
symbol and vector remain on the screen un-
til the dangerous situation is no longer present
or you intentionally terminate tracking of the
target by using the [SELECT/CANCEL] key.
Provided that this feature is used correctly, it
will help prevent the risk of collision by alert-
ing you to threatening targets. It is important
that GAIN, A/C SEA, A/C RAIN and other
radar controls are properly adjusted and the
Auto Plotter is set up so that it can track tar-
gets effectively.