Question 19 GLI01 - Master-Unlimited Tonnage

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 collision risk (under both International Regulations for Preventing Collisions at Sea - COLREGs - Rule 7) is that **risk of collision exists if there is no appreciable change in the compass bearing of an approaching vessel, even if the range (distance) is increasing or decreasing.** If a vessel's bearing remains constant, it means that if both vessels maintain their current course and speed, they are following paths that will intersect at the same point in space and time. This situation, known as a **Constant Bearing, Decreasing Range (CBDR)**, is the classic definition of an imminent collision risk. Although the vessel is on your quarter (implying you are the Stand-on vessel in a typical overtaking situation, or possibly a Crossing situation if the quarter angle is close to the beam), the presence of a constant bearing and decreasing range signifies a definite and dangerous risk of collision. *** ### Why Other Options Are Incorrect: * **B) A vessel is 22 degrees abaft your port beam, range increasing, bearing is constant.** * While the constant bearing suggests the paths *might* intersect if ranges were decreasing, the **range is increasing**. This means the vessel is moving away from the point of intersection faster than you are moving toward it (or you are moving away from it). Therefore, the risk of collision does not definitely exist; the vessels are separating. * **C) A vessel is broad on your starboard beam, range decreasing, bearing changing rapidly to the right.** * The **bearing is changing rapidly**. A rapid change in bearing, even with decreasing range, indicates that the vessels will pass clear of each other. The rapid bearing change means the relative motion is substantial and separation will occur. * **D) A vessel is 22 degrees on your port bow, range increasing, bearing changing slightly to the right.** * Both the **range is increasing** (vessels are separating) and the **bearing is changing** (paths are not currently intersecting at the same point). Both factors confirm that risk of collision does not definitely exist.