Which signal indicates that a vessel is at anchor?

• A. One short, one prolonged, and one short.
• B. One prolonged blast.
• C. Two prolonged blasts.
• D. Five short blasts.

Answer: (A)

The main idea here is how ships communicate status through sound signals. When a vessel is at anchor, it uses a distinctive three-beat pattern to let others know it isn’t moving under its own power. That pattern is one short blast, followed by one prolonged (long) blast, and then one short blast. This combination is specifically used to indicate that the vessel is anchored.

In addition to sound signals, a vessel at anchor also displays a day shape (a black ball) to signal its status to other vessels during daylight. The other sound patterns listed do not convey anchored status, so they wouldn’t be the correct way to indicate that a vessel is at anchor.