Question 19 ONC06 - Master LT 100 GRT

The Correct Answer is A. **Why option A is correct:** Risk of collision exists if the bearing of an approaching vessel does not appreciably change (Rule 7(a)(i) of the International Regulations for Preventing Collisions at Sea (COLREGS)). A **constant bearing, decreasing range (CBDR)** is the primary indicator of a collision risk. Although the vessel is on your starboard quarter (usually indicating you are the overtaking vessel, which must keep clear), the combination of a constant bearing and decreasing range means that if both vessels maintain their course and speed, they will arrive at the same point at the same time, leading to a collision. **Why the other options are incorrect:** * **B) A vessel is 22 degrees abaft your port beam, range increasing, bearing is constant.** While the bearing is constant (suggesting risk), the **range is increasing**. This means the vessel is moving away from you and the point of potential intersection is already past, or the vessel is significantly faster but moving away on a parallel or diverging course, meaning no risk of collision exists. * **C) A vessel is broad on your starboard beam, range decreasing, bearing changing rapidly to the right.** Although the range is decreasing, the **bearing is changing rapidly**. A rapid change in bearing indicates that the other vessel is crossing ahead or astern of you, and will clear your path, thus eliminating the risk of collision (unless the speed of the bearing change slows down significantly later). * **D) A vessel is 22 degrees on your port bow, range increasing, bearing changing slightly to the right.** Because the **range is increasing**, the vessels are separating. Even though the bearing change is slight, the increasing separation confirms that no risk of collision exists.