Question 19 GLI03 - Master-LT 500-1600 GRT

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 risk of collision, applicable internationally and inland (COLREGs Rule 7(b)), is that such risk shall be deemed to exist if the compass bearing of an approaching vessel does not appreciably change. This is the definition of Constant Bearing, Decreasing Range (CBDR). * **Bearing is Constant:** This satisfies the primary condition for risk of collision (Rule 7(b)). * **Range Decreasing:** This indicates the vessels are closing. * **Starboard Quarter:** While this position means the vessel is currently overtaking you (COLREGs Rule 13), risk of collision *definitely exists* because the CBDR condition is met. The overtaking vessel (in A) is required to keep clear until finally past and clear, but the risk of collision remains until they pass, and the responsibility to monitor the situation rests with both vessels. Meeting the CBDR criterion means the risk of collision is confirmed. ### Why Other Options Are Incorrect **B) A vessel is 22 degrees abaft your port beam, range increasing, bearing is constant.** Risk of collision is unlikely. While the bearing is constant (suggesting a potential collision course if the vessels maintained speed), the **range is increasing**. This means the vessels are moving apart, and therefore, they will not meet unless one or both alter speed or course significantly. CBDR requires decreasing range. **C) A vessel is broad on your starboard beam, range decreasing, bearing changing rapidly to the right.** Risk of collision is unlikely. Although the range is decreasing (vessels are closing), the **bearing is changing rapidly**. A rapid change in bearing means the vessels are on courses that will cause them to pass clear of each other, satisfying the requirement in Rule 7(d)(i) that safe passing is indicated if the bearing changes significantly. **D) A vessel is 22 degrees on your port bow, range increasing, bearing changing slightly to the right.** Risk of collision is unlikely. Both conditions that indicate a potential risk (constant bearing and decreasing range) are absent: * The **range is increasing** (they are moving apart). * The **bearing is changing** (their courses are already projected to pass clear).