BOTH INTERNATIONAL & INLAND Vessels "A" and "B" are meeting in a narrow channel as shown in illustration D029RR below but are not in sight of one another due to restricted visibility. Which statement is TRUE concerning whistle signals between the vessels?

Correct Answer: Option D — None of the above statements is TRUE.

Rule 34 maneuvering and warning signals, such as short blasts, are strictly permitted only when vessels are in sight of one another. Because these vessels are in restricted visibility and not in sight, they must sound fog signals under Rule 35 instead.