Observe and identify
Advanced level, about 3 min. International COLREGs / IRPCS.
The situation
A faster vessel astern, in sight, proposes passing on your starboard side in a narrow fairway. Another vessel already occupies that passage. You cannot safely make the room requested.
What should you signal?
- Sound at least five short, rapid blasts
- Sound the overtaking agreement
- Make no reply
Answers and explanations
Lookout: Assess the water available for the proposed passage before replying.
The sound answer
Sound at least five short, rapid blasts
Sound the signal of doubt; an overtaking proposal is not permission to use occupied water. Keep observing and take appropriate precautions.
Why the other options fall short
Sound the overtaking agreement
Do not agree to an unsafe passage. Signal doubt and maintain a proper lookout.
Make no reply
Silence does not communicate the danger you have identified. Sound the signal of doubt.
Rules 9(e) & 34(d) · Unsafe passage
Use at least five short, rapid blasts when approaching vessels in sight are uncertain about intentions or sufficient collision avoidance. Keep safe passage under review.