BOTH INTERNATIONAL & INLAND While underway in fog, you hear a vessel ahead sound two prolonged blasts on the whistle. Which action should you take?

Correct Answer: Option D — sound only fog signals until the other vessel is sighted

Rule 34(a) regarding maneuvering and warning signals applies only to vessels in sight of one another. In restricted visibility, Rule 35 governs. You must continue sounding the appropriate fog signals prescribed by Rule 35 until the other vessel is visually sighted, at which point maneuvering signals may be exchanged.