Ternav 3

When using a radar to determine a position circle, what does the compass or parallel ruler setting represent?

• The direction the ship is traveling

• The actual size of the charted object

• The scale at which the radar distance translates to chart distance

• The time it takes for the radar signal to travel to the object

The accuracy of a position fix from simultaneous cross bearings is most dependent on:

• The distance between the ship and the charted objects

• The angle formed by the intersection of the bearing lines

• The type of compass used for taking the bearings

• The speed of the ship at the time of measurement

What information is NOT required when plotting a position from bearing and distance off?

• The compass bearing of a fixed object

• The distance to the fixed object measured with radar

• The type of navigational chart being used

• The speed of the ship relative to the fixed object

According to the passage, what is the main advantage of plotting a position circle compared to using simultaneous cross bearings?

• Position circles require less information to plot.

• Cross bearings are always more accurate than position circles

• Position circles account for uncertainty in the ship's exact location.

• Position circles are only useful for fixing positions at night.

The passage mentions the importance of marking the time on a position circle. What is the primary reason for doing this?

• To comply with international maritime regulations

• To calculate the speed of the ship over time

• To differentiate between multiple position fixes taken throughout a voyage

• To compensate for any errors in the radar measurement

What is the main advantage of using a pelorus and assistant for taking bearings compared to a single observer with a compass?

• The pelorus provides more accurate compass readings.

• It minimizes the error in time between measuring bearings of two objects.

• The pelorus allows for taking bearings at night more easily.

• A pelorus is a more portable navigational tool.

A gyrocompass offers a significant benefit over a magnetic compass because:

• A gyrocompass requires less maintenance.

• It is affected by nearby magnetic fields on the ship.

• Gyrocompasses provide more stable and accurate heading readings.

• A gyrocompass can be used for navigation in any weather condition.

Electronic Bearing Systems (EBL/ECDIS) provide an improvement over traditional methods like a pelorus for taking bearings because:

• They eliminate the need for an assistant during measurement.

• Electronic systems are more resistant to damage in rough seas.

• They allow for near-simultaneous electronic measurement and display of bearings on a chart.

• Electronic bearings are not affected by human error in reading compass scales

A dead reckoning (DR) position is most likely to be inaccurate when:

• The vessel is using a gyrocompass for heading information.

• The journey is along a straight course at constant speed.

• The last fix was obtained a short time ago.

• The vessel is navigating through strong currents or winds.

The term "estimated position" (EP) is broader than "dead reckoning" (DR) because:

• An EP requires more complex calculations than DR.

• An EP can incorporate information beyond just course, speed, and time

• DR positions are only estimates for short distances.

• EPs are less reliable than DR positions for navigation.