Question 19 GLI07 - OUPV

The Correct Answer is A. A vessel is on your starboard quarter, range decreasing, bearing is constant. ### Why Option A is Correct The fundamental rule for determining the risk of collision (according to both International and Inland Rules, Rule 7(a)(i)) is that such risk shall be deemed to exist if the Compass Bearing of an approaching vessel does not appreciably change. Option A states: "A vessel is on your starboard quarter, **range decreasing**, **bearing is constant**." 1. **Bearing is constant (or non-changing):** This is the definitive indicator of a potential collision course (Constant Bearing, Decreasing Range - CBDR). The vessel is heading toward your same position. 2. **Range decreasing:** This confirms that the vessels are closing the distance between them, meaning the time to the point of closest approach (CPA) is decreasing, which necessitates action to avoid collision. Therefore, the combination of constant bearing and decreasing range unequivocally confirms the existence of a risk of collision. ### Why the Other Options are Incorrect **B) A vessel is 22 degrees abaft your port beam, range increasing, bearing is constant.** * **Range increasing:** The vessel is moving away from you. While the bearing is constant (meaning the CPA would be zero miles if the range were not changing), because the range is increasing, the vessels are diverging, and no risk of collision exists. **C) A vessel is broad on your starboard beam, range decreasing, bearing changing rapidly to the right.** * **Bearing changing rapidly:** A rapid change in bearing means the other vessel is moving well ahead of or astern of your predicted path. Although the range is decreasing, the vessels will pass clear of each other, likely resulting in a large CPA. No immediate risk of collision exists. **D) A vessel is 22 degrees on your port bow, range increasing, bearing changing slightly to the right.** * **Range increasing:** The vessel is moving away from you. * **Bearing changing:** The vessel is not on a CBDR course. * The combination of increasing range and changing bearing means the vessels are diverging safely, and no risk of collision exists.