Question 42 RVR05 - Master of LT 100 GRT

The Correct Answer is A. **Explanation of Option A (Correct Answer):** According to Rule 27(a) of the International Regulations for Preventing Collisions at Sea (COLREGs), a vessel not under command (NUC) must exhibit two all-round red lights in a vertical line where they can best be seen. This signal indicates the vessel's inability to maneuver and is mandatory regardless of whether the vessel is making way or not. Since the vessel in the question is "underway but not making way," this two all-round red light signal is the fundamental daylight and nighttime requirement for its NUC status. **Explanation of Other Options (Incorrect):** * **B) a stern light:** A vessel that is "underway but not making way" (i.e., stopped relative to the water but not anchored) and is *not under command* (NUC) is required to show the two all-round red lights (Rule 27(a)). If the NUC vessel is *not making way* through the water, it **does not** exhibit the masthead lights, stern light, or sidelights typically required for a power-driven vessel underway (Rule 27(b)). Therefore, exhibiting only the stern light is incorrect. * **C) sidelights:** Similar to the stern light, if the NUC vessel is "not making way" through the water, it must *not* exhibit the sidelights (Rule 27(b)). Sidelights and stern lights are required only if the NUC vessel is making way through the water. * **D) All of the above:** Since options B and C are incorrect for a vessel NUC that is "not making way," this aggregate option is incorrect. The mandatory display when not making way is solely the two all-round red lights.