Which signal sequence indicates a vessel at anchor when there is a possibility of collision?

• A. Two short blasts
• B. One short, one long, and one short
• C. Three short blasts
• D. One long blast

Answer: (B)

The key idea is that sound signals communicate a vessel’s status to nearby ships in restricted visibility or when there’s a risk of collision. When a vessel is at anchor and there is a possibility of collision, the recognized signal is a pattern of one short blast, followed by one long blast, then another short blast. This specific sequence is designed to stand out and clearly convey that the vessel is anchored but may affect other vessels’ passage, prompting them to take appropriate action to avoid a collision.

Hearing this pattern tells you to keep a careful look and be prepared to adjust your course or speed as needed to ensure safe clearance, since the anchored vessel could be a collision risk depending on your approach.