AB Navigation & Watchstanding 3 — Questions and Answers
Question 1: A power-driven vessel underway in good visibility is overtaking a sailing vessel. Which vessel has the right-of-way?
- The power-driven vessel because it has better maneuverability
- The sailing vessel, since power gives way to sail in all circumstances
- The sailing vessel, because the overtaking vessel must keep clear regardless of propulsion type (Correct answer)
- Neither — both must take action to avoid collision
Correct answer: The sailing vessel, because the overtaking vessel must keep clear regardless of propulsion type
Rule 13 states that any vessel overtaking another must keep clear; the overtaking rule takes precedence over the power-versus-sail rule.
Question 2: When using a depth sounder to navigate along a charted depth contour, the helmsman must account for:
- Variation and deviation
- The height of tide at the time of observation (Correct answer)
- The vessel's air draft clearance
- The difference between apparent and true wind
Correct answer: The height of tide at the time of observation
Chart depths are referenced to a datum such as MLLW, so the actual depth under the keel equals the charted depth plus (or minus) the height of tide.
Question 3: You are on anchor watch and notice the vessel has dragged anchor. After alerting the master, your immediate duty regarding navigation is to:
- Plot the new position and determine drift rate and direction (Correct answer)
- Slip the anchor chain to allow the vessel to proceed
- Sound the fog signal since the vessel is now underway
- Switch navigation lights from anchor light to underway lights immediately
Correct answer: Plot the new position and determine drift rate and direction
Determining the new position, drift rate, and direction toward any hazard is essential information the master needs to decide the emergency response.
Question 4: What does a flashing blue light displayed by a vessel indicate under US regulations?
- The vessel is engaged in diving operations
- The vessel is a law enforcement vessel (Correct answer)
- The vessel is a pilot vessel on duty
- The vessel is towing a submerged object
Correct answer: The vessel is a law enforcement vessel
Under 33 CFR, US law enforcement vessels may display a flashing blue light when engaged in direct law enforcement activities.
Question 5: The term 'set' as applied to current refers to:
- The speed of the current in knots
- The direction toward which the current flows (Correct answer)
- The total distance the vessel has been displaced by current
- The difference between the charted course and the course made good
Correct answer: The direction toward which the current flows
Set is the direction toward which a current flows, expressed as a true bearing; drift is the speed of the current in knots.
Question 6: During your watch you receive a SECURITE call on VHF Channel 16. This call indicates:
- A vessel in grave and imminent danger requiring immediate assistance
- An urgency message concerning the safety of a person or vessel
- A navigational or meteorological warning of importance to mariners (Correct answer)
- A routine announcement from a port authority about traffic movements
Correct answer: A navigational or meteorological warning of importance to mariners
SECURITE is the safety signal used to precede messages about navigational or meteorological hazards that are important to all mariners.
Question 7: When a vessel's course is expressed as a 'true course,' it is measured from:
- Magnetic north, corrected for deviation
- True (geographic) north, as found on the meridians of a chart (Correct answer)
- Compass north, before applying variation or deviation
- Magnetic north, corrected for variation only
Correct answer: True (geographic) north, as found on the meridians of a chart
A true course is measured clockwise from true (geographic) north — the north shown by the meridians printed on a nautical chart.
AB Navigation & Watchstanding 3
A power-driven vessel underway in good visibility is overtaking a sailing vessel.
Which vessel has the right-of-way?