Furuno 1942 MARK-2 manual Mode and Length of Vectors, Past Position Display, Operational Warnings

6.5Mode 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

CAUTION

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.

Visual and audible alarm are generated when the predicted CPA and TCPA 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 CPA 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.

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