BOTH INTERNATIONAL & INLAND While underway in fog, you hear a short blast, a prolonged blast, and a short blast of a whistle. This signal indicates which vessel(s)?

Correct Answer: Option C — A vessel anchored in fog

Rule 35(g) specifies that a vessel at anchor shall at intervals of not more than one minute ring the bell rapidly for about five seconds. In some jurisdictions, this is preceded by a short, prolonged, and short blast to indicate the vessel is at anchor and warning approaching vessels.