Question 19 ONC04 - Mate of LT 500-1600 GRT

The Correct Answer is A. **Explanation for Option A (Correct):** The fundamental rule for determining risk of collision (applicable both internationally and inland) is based on observing a vessel's bearing and range. If the compass bearing of an approaching vessel does not appreciably change, **and** the range (distance) is decreasing, a risk of collision definitely exists. The statement "A vessel is on your starboard quarter, range decreasing, bearing is constant" describes a situation where the other vessel is directly approaching the intersection point of your current course and theirs. Even though the vessel is starting in the quarter (which often implies it is overtaking), the key indicators—constant bearing and decreasing range—satisfy the definition of risk of collision as outlined in Rule 7(a)(i) of the COLREGs (International Regulations for Preventing Collisions at Sea). **Explanation of Why Other Options Are Incorrect:** * **B) A vessel is 22 degrees abaft your port beam, range increasing, bearing is constant.** * **Incorrect because:** Although the bearing is constant, the range is **increasing**. This means the vessel is moving away from your track and any potential point of collision. Risk of collision does not exist. * **C) A vessel is broad on your starboard beam, range decreasing, bearing changing rapidly to the right.** * **Incorrect because:** The bearing is **changing rapidly**. A rapid change in bearing, even with decreasing range, indicates that the relative movement of the other vessel will cause it to pass clear of your track. The rapid change in bearing negates the immediate risk of collision, as defined by Rule 7. * **D) A vessel is 22 degrees on your port bow, range increasing, bearing changing slightly to the right.** * **Incorrect because:** Both indicators—range **increasing** and bearing **changing**—show that the vessel is moving away and passing safely clear. Risk of collision does not exist.