In a narrow channel, if another vessel is crossing your course from starboard to port and you do not think she will pass safely, you ________.

• A. Must sound the danger signal
• B. Must alter course to pass ahead of her
• C. Must raise the flag and stop
• D. Must assume she will pass safely

Answer: (A)

When two vessels are on crossing courses and there’s doubt about safe passage, alerting the other vessel is the first proper step. The danger signal, five short blasts on the whistle, is the explicit way to communicate that there is a potential risk of collision or that the other vessel may not be taking appropriate action. In a narrow channel, where maneuvering space is tight, signaling helps prevent misunderstanding and prompts the other vessel to adjust course, speed, or both as needed.

After sounding, you should continue to take action to avoid collision in accordance with the rules, such as adjusting your own course or speed if safe to do so. The other options don’t fit because there isn’t a formal signal to “raise a flag and stop,” and assuming the other vessel will pass safely or attempting to pass ahead without addressing the risk isn’t prudent in a collision situation.