Furuno ARP-17 Past Position Display, Set and Drift, Displaying data, Selecting plotting interval

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Displaying data

Place the cursor on a wanted target and press the [ENTER/SELECT] key. Data on the se- lected target is displayed on the screen. The data includes the follows;

BRG/RNG (Bearing/Range): RNG/BRG

(Range/Bearing): Range and bearing from own ship to the selected target with suffix “T” (True) or “R” (Relative).

CSE/SPD (Course/Speed): Course and speed are displayed for the selected target with suffix “T” (True) or “R” (relative).

CPA (Closest Point of Approach) is the clos- est 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 cal- culated. When a target ship has passed clear of own ship, the CPA is displayed and the TCPA appears as “xx.x”. TCPA is counted up to 99.59 min. and beyond this it is indicated as TCPA>99.59 min.

Note 1: MARK DISP on PLOT MENU 1 must be turned on to display target data.

10. Past Position Display

The ATA displays equally time-spaced dots (maximum 10 dots at intervals of 30 s, 1, 2, 3 or 6 min) 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 plot- ted course will not be a straight line in TM mode. In TM, the past position display is pro- duced relative to North (True Trails). In RM, it is relative to North or Heading as selected.

To turn the past position display on/off:

1.Press [MENU], [7], [7] to display PLOT MENU 1.

2.Press the [7] key to select ON or OFF from the TRACK field.

(a) Ship turning

(b) Ship running

 

straight

(c) Ship reduced

(d) Ship increased

speed

speed

Figure 8 Past position display examples

Selecting plotting interval

On PLOT MENU 1, select desired past posi- tion display plotting interval among 30 sec, 1 min, 2 min, 3 min or 6 min from 9. INTVAL.

11. Set and Drift

Set, the direction of ocean current, can be manually entered in the nearest degree. Drift, the speed of current, can also be entered manually, in 0.1 knot increments. Set and drift corrections are beneficial for increasing the accuracy of the vector data. The correction is best made on relative motion with true vec- tor, watching landmasses, buoys, or station- ary targets. Thus, the speed and course of own ship over the ground are reciprocally calculated and compared with the relative bearing and range to the reference target to produce a Set and Drift. These values are applied to all targets. If stationary objects have vectors, the set and drift should be cor- rected until they lose their vectors.

If own ship is equipped with a device to indi- cate ocean current movements, the values shown on it may be used.

1.Press [MENU], [0], [0] to display the OTHER menu.

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Contents Automatic Tracking AID B . N o . O M E 3 0 4 6 Safety Instructions Table of Contents Word to Furuno ARP-17 Owners FeaturesForeword Criteria of Tracking Operational OverviewIntroduction Acquisition and trackingOwn ship maneuvers Qualitative description of tracking errorAutomatic acquisition areas and suppression lines Other ship maneuversControls, Menu Description ControlsMenu tree Menu descriptionAutomatic speed input Activating, Deactivating the ATAEntering Own Ship’s Speed Target-based speed input Acquiring TargetsManual speed input Manual acquisitionChanging plot symbol shape Automatic acquisitionDisplaying Target Data Terminating Tracking of TargetsVectors Displaying data Past Position DisplaySet and Drift Selecting plotting intervalAlarms CPA/TCPA alarmGuard zone alarm Silencing CPA/TCPA audible alarmLost target alarm Track Test Simulation DisplayDiagnostic Sequence CPA TcpaOutputting Target Data Specifications of Auto Plotter Index