Question 19 ONC03 - Master LT 500-1600 GRT

The Correct Answer is A. **Explanation for Option A (Correct Answer):** The rule for determining risk of collision is based on analyzing whether the Compass Bearing of an approaching vessel changes appreciably. If the bearing remains constant while the range decreases, a **Close Quarters Situation (CCS)** is developing, and a **risk of collision definitely exists** according to Rule 7(a)(i) of the International Regulations for Preventing Collisions at Sea (COLREGs). Although the vessel is currently on your starboard quarter, the fact that the range is decreasing and the bearing is constant means that both vessels are converging directly onto the same point. This situation is the classic definition of a collision course. **Explanation for Incorrect Options:** **B) A vessel is 22 degrees abaft your port beam, range increasing, bearing is constant.** Risk of collision does not exist because the range is increasing (the vessel is moving away from you). Even though the bearing is constant, the separation distance is growing, meaning no collision course is possible. **C) A vessel is broad on your starboard beam, range decreasing, bearing changing rapidly to the right.** Risk of collision does not definitely exist. While the range is decreasing, the bearing is changing rapidly. A rapid change in bearing means the vessels are likely crossing or passing with a good CPA (Closest Point of Approach). The vessel is moving substantially across your bow or stern, indicating a non-collision course. **D) A vessel is 22 degrees on your port bow, range increasing, bearing changing slightly to the right.** Risk of collision does not exist because the range is increasing (the vessel is moving away). While a small change in bearing *might* indicate a slow CPA development if the range were decreasing, the increasing range definitively rules out a collision.