Key Topic 36: ARPA - CAS

Question 1

8-36D1: The ship’s speed indication on the ARPA display can be set manually, but does not change with changes in the vessel’s speed. What other indication would point to a related equipment failure?

A. “GYRO OUT” is displayed on the ARPA indicator.
B. “LOG OUT” is displayed on the ARPA indicator.
C. “TARGET LOST’ is displayed on the ARPA indicator.
D. “NORTH UP” is displayed on the ARPA indicator.

Answer 1

B. “LOG OUT” is displayed on the ARPA indicator.

Question 2

8-36D2: What does the term ARPA/CAS refer to?

A. The basic RADAR system in operation.
B. The device which displays the optional U.S.C.G. Acquisition and Search RADAR information on a CRT display.
C. The device which acquires and tracks targets that are displayed on the RADAR indicator’s CRT.
D. The device which allows the ship to automatically steer around potential hazards.

Answer 2

C. The device which acquires and tracks targets that are displayed on the RADAR indicator’s CRT.

Question 3

8-36D3: Which of the following would not be considered an input to the computer of a collision avoidance system?

A. Own ship’s exact position from navigation satellite receiver.
B. Own ship’s gyrocompass heading.
C. Own ship’s speed from Doppler log.
D. Own Ship’s wind velocity from an anemometer.

Answer 3

D. Own Ship’s wind velocity from an anemometer.

Question 4

8-36D4: Which answer best describes a line on the display which indicates a target’s position. The speed is shown by the length of the line and the course by the direction of the line.

A. Vector.
B. Electronic Bearing Line.
C. Range marker.
D. Heading Marker.

Answer 4

A. Vector.

Question 5

8-36D5: What is the purpose of function of the “Trial Mode” used in most ARPA equipment?

A. It selects trial dots for targets’ recent past positions.
B. It is used to display target position and your own ship’s data such as TCPA, CPA, etc.
C. It is used to allow results of proposed maneuvers to be assessed.
D. None of these.

Answer 5

C. It is used to allow results of proposed maneuvers to be assessed.

Question 6

8-36D6: The ARPA term CPA refers to:

A. The furthest point a ship or target will get to your own ship’s bow.
B. Direction of target relative to your own ship’s direction.
C. The combined detection and processing of targets.
D. The closest point a ship or target will approach your own ship.

Answer 6

D. The closest point a ship or target will approach your own ship.