Navigation Quiz - Nautical Concepts

Competency 1 Assessment - Deck

• Position Determination:

  • Dead-reckoning: Position calculated using only vessel's course and speed from a known position.
  • Estimated Position: Position calculated using estimated current and wind, in addition to vessel's course and speed.
  • Probable Position: Position estimated based on data which is not precise.
  • Applied Position: Position calculated using applied current and wind from known position
  • Fix: Exact position determined by multiple methods.

• Barometric Pressure:

  • 29.92 inches of mercury is equivalent to 1013.25 millibars.

• Apparent Altitude:

  • Sextant altitude corrected for reading and reference level inaccuracies, double-second difference, chronometer error, and dip.

• Tidal Currents:

  • Data about the direction and velocity of rotary tidal currents can be found in Tidal Current Tables.

• Speed of Sound in Water:

  • 1.44 kilometers per second.

• Echo Sounder Frequency:

  • Low frequency pulse of the echo sounder is 24 kHz.

• Echo Sounder Line Marking:

  • Event marker (used to mark events on the plotted line).

• Water Salinity Effect on Sound:

  • Increases the speed of sound.

• Nature of Echo Sounder Beam:

  • Directional.

• Echo Sounder Transducer Types:

  • Magnetostriction is one transducer type.

• False Echoes in Echo Sounder:

  • Causes include turbulence from tidal streams, schools of large fish, and bioluminescent microorganisms in the water.

• Torque-Induced Precession:

  • Wobbling of an object's axis when torque is applied.

• Gyrocompass Errors:

  • Stream error results from rapid changes in course, speed or latitude causing errors before gyrocompass can adjust.

• Flinders Bar on Compass:

  • Correct statement: compensates for error caused by the vertical component of the Earth's magnetic field.

• Determining Deviation (Heading):

  • Gyro error, variation and deviation should all be considered.

• Distance between points on Earth:

  • Shortest distance is defined as a great circle.

• Charts covering large areas:

  • Small-scale charts cover larger areas.

• Isogonic Lines:

  • Indicate lines of equal magnetic variation on a chart.

• Chart Revisions:

  • Printed in the lower left center of the chart.

• Light Visibility on Charts:

  • Typically measured in nautical miles for charted and luminous ranges.

• Mercator Chart Projection:

  • A cylindrical projection.

• Coral Chart Symbol:

  • Typically a symbol of an orange or red cross-hatched pattern.

• Ocean Current Information Source (Voyage Planning):

  • Sailing Directions.

• GPS Accuracy:

  • Accuracy is expected to be 95% within 100 meters (for GPS).

• DGPS Accuracy:

  • Accuracy within 10 meters is expected with DGPS navigation systems.

• Magnetic Variation:

  • The angle between the grid and magnetic meridians is known as variation.

• Steering Compass (Gyro effect):

  • Gyro compass reaction to force is known as precession.

• Navigation Instrument (Bearing and Course):

  • Compass and Pelorus.

• Compass Rose Indicator (Nautical chart):

  • Variation and deviation are indicated.

• Atmospheric pressure:

  • Standard is 760 mm of mercury.

• Navigational Actions (problems):

  • When Notice Vessel's course is slowly changing right—switch to hand steering and then immediately notify the engineroom.

• Arctic Circle Latitude:

  • 66.5 degrees North.

• Automatic Steering Device:

  • Gyropilot is automatic steering device using a gyrocompass.

• Nautical Mile:

  • 6,076 feet, 1.852 kilometers

• Twilight Interval:

  • Astronomical twilight defines the time when the center of the sun is 12 degrees below the horizon.

• Notices of Marine Casualty

  • Notice needed for incidents involving damage to the vessel, or to the cargo.