Master Yachts | Manual Radar Plotting

Question 1

RADAR PLOTTING

What does ‘WO’ mean?

Answer 1

• Way of Own
• Direction of arrow from ‘W’ to ‘O’
• Own ships track and speed vector for the given time interval

Question 2

RADAR PLOTTING

What does ‘WA’ mean?

Answer 2

• Way of Another
• The targets vessel’s true track and speed vector for the given time interval.
• Direction of arrow from ‘W’ to ‘A’

Question 3

RADAR PLOTTING

Define the following:
* O
* A
* W

Answer 3

• O - Original position of target prior to plotting
• A - Actual position of the target at last plot
• W - The zero speed position (ZSP)

Question 4

RADAR PLOTTING

What should a Radar Plot Report contain?

Answer 4

• Bearing and distance of CPA
• Time to and time of CPA
• Target track and speed
• Aspect

Question 5

RADAR PLOTTING

What is the formula for finding TCPA?

Answer 5

A to CPA distance/O to A distance
x O to A time difference

Question 6

RADAR PLOTTING

What is the formula for finding the aspect?

Answer 6

Target course - reciprocal of last plot

Question 7

ARPA INTERPRETATION

If own ship has a vector, what vector mode is the display in?

Answer 7

True vector.

Question 8

ARPA INTERPRETATION

If own ship has no trails, what type of trail has been set?

Answer 8

Relative trails

Question 9

ARPA INTERPRETATION

How can you tell what stabilisation is being used?

Answer 9

Look for fixed target, if ground stabilised it will not have true trail or true vector.

Question 10

ARPA INTERPRETATION

What indication can be displayed for tide and leeway?

Answer 10

By using the vector from a fixed object.

Question 11

ARPA INTERPRETATION

Why would a target have no vector when sea stabilised display?

Answer 11

Target doing zero knots through the water

Question 12

ARPA INTERPRETATION

How can you quickly know if there may be a close quarters situation?

Answer 12

Look for relative trails or vectors.