NASBLA Navigation Rules & Right of Way 2 — Questions and Answers
Question 1: What lights must a power-driven vessel less than 50 meters in length display when underway at night?
- Masthead light, sidelights, and a sternlight (Correct answer)
- Two masthead lights, sidelights, and a sternlight
- Sidelights and an all-round white light only
- Masthead light and an all-round white light
Correct answer: Masthead light, sidelights, and a sternlight
A power-driven vessel under 50 meters underway must show one masthead light forward, sidelights (red/green), and a white sternlight per Rule 23.
Question 2: What does three short blasts on a vessel's whistle signal mean when vessels are in sight of each other?
- My engines are going astern (Correct answer)
- I am altering my course to port
- I am unable to maneuver
- Danger — stand clear
Correct answer: My engines are going astern
Rule 34 specifies that three short blasts is the maneuvering signal for operating engines in reverse (astern propulsion).
Question 3: What sound signal must a vessel at anchor in restricted visibility sound every two minutes?
- Ring the bell rapidly for about five seconds (Correct answer)
- One prolonged blast
- Two short blasts followed by one prolonged blast
- Three short blasts
Correct answer: Ring the bell rapidly for about five seconds
Rule 35 requires a vessel at anchor to ring a bell rapidly for about five seconds every two minutes in restricted visibility.
Question 4: What does a red sidelight on a vessel indicate to an observer?
- The observer is viewing the vessel's port side (Correct answer)
- The observer is viewing the vessel's starboard side
- The vessel is operating in reverse
- The vessel is a sailing vessel
Correct answer: The observer is viewing the vessel's port side
Red sidelights are mounted on the port (left) side; if you see a red light you are viewing the vessel from its port side.
Question 5: Under Rule 19 (Restricted Visibility), what speed must a vessel maintain?
- A safe speed adapted to the prevailing conditions of restricted visibility (Correct answer)
- Dead slow ahead at all times
- No more than 5 knots
- The same speed as in good visibility
Correct answer: A safe speed adapted to the prevailing conditions of restricted visibility
Rule 19 requires vessels in or near restricted visibility to proceed at a safe speed adapted to the conditions, not a specific numerical limit.
Question 6: What is the minimum sounding interval for a power-driven vessel making way in restricted visibility?
- One prolonged blast at intervals of not more than two minutes (Correct answer)
- One prolonged blast at intervals of not more than one minute
- Two short blasts at intervals of not more than two minutes
- One short and one prolonged blast every minute
Correct answer: One prolonged blast at intervals of not more than two minutes
Rule 35 requires a power-driven vessel making way in restricted visibility to sound one prolonged blast at intervals of not more than two minutes.
Question 7: What do sidelights on a vessel indicate regarding the arc of visibility?
- Each sidelight covers an arc of 112.5 degrees (Correct answer)
- Each sidelight covers an arc of 180 degrees
- Each sidelight covers an arc of 135 degrees
- Each sidelight covers an arc of 90 degrees
Correct answer: Each sidelight covers an arc of 112.5 degrees
Under Rule 21, each sidelight must cover an arc of the horizon of 112.5 degrees, from dead ahead to 22.5 degrees abaft the beam.
NASBLA Navigation Rules & Right of Way 2
What lights must a power-driven vessel less than 50 meters in length display when underway at night?