BOTH INTERNATIONAL & INLAND You are approaching another vessel on crossing courses. She is about one mile distant and is on your starboard bow. You believe she will cross ahead of you but she sounds a whistle signal of five short blasts. Which action should you take?

Correct Answer: Option C — make a large course change, and slow down if necessary

Rule 34(d) defines the danger signal as at least five short and rapid blasts. When a vessel sounds this, it indicates doubt regarding the other's actions. Under Rule 8, you must take positive, early action, including a large course change or slowing down, to ensure safe passage.