In a scenario where a vessel on your starboard quarter has decreasing range but constant bearing, what does this indicate about collision risk?

• A. No collision risk
• B. Definite risk of collision
• C. Risk only if speed changes
• D. Risk is minimal

Answer: (B)

Recognizing a potential collision comes from watching relative motion. When another vessel is in your vicinity and the range to it is decreasing while the bearing to it stays essentially the same, you are on a collision course unless one of you alters course or speed. The constant bearing means your lines of travel are aligned in a way that keeps them from passing to one side, and the shrinking distance means you’re closing in. In this situation, there is a definite risk of collision, so you would need to take early and decisive action to avoid, especially since the other vessel is on your starboard quarter and has the right-of-way in that crossing scenario.