Question 2

The Correct Answer is C. ### Explanation for Option C (white stern light) Option C is correct because the scenario described is an overtaking situation. Vessel "A" is overtaking vessel "B" and will pass without changing course. According to the International Regulations for Preventing Collisions at Sea (COLREGs), a vessel is deemed to be an overtaking vessel when she is approaching another vessel from a direction more than $22.5$ degrees abaft her beam (Rule 13). In this arc, the overtaking vessel (A) can see only the **sternlight** of the vessel being overtaken (B) at night. The sternlight is a white light placed as nearly as practicable at the stern, showing an unbroken light over an arc of the horizon of $135$ degrees ($67.5$ degrees from right aft on each side). When Vessel A is directly behind Vessel B and passing, the white stern light is the only navigational light Vessel A will observe on Vessel B. ### Explanation for Incorrect Options **A) green sidelight:** The green sidelight (starboard light) shows an unbroken light over an arc of the horizon of $112.5$ degrees, extending from right ahead to $22.5$ degrees abaft the beam on the starboard side. Since Vessel A is approaching from behind (in the arc of the sternlight), Vessel A cannot see the green sidelight of Vessel B. **B) yellow towing light:** A yellow towing light is required only for vessels engaged in towing (Rule 24). The prompt does not state that Vessel B is towing. Even if Vessel B were towing, Vessel A would still observe the white stern light first (and possibly the masthead lights and side lights, depending on the length of the tow), but the towing light is specific to towing operations and not required for every vessel. In a general overtaking situation, the mandatory light seen is the stern light, not the towing light. **D) None of the above:** This is incorrect because the white stern light (Option C) is the correct light observed in this specific overtaking scenario.