Question 28 GLI08 - Limited OUPV

The Correct Answer is B **Explanation for Option B (Correct):** Navigation lights are mandatory from sunset to sunrise. However, international and inland navigation regulations (specifically, the COLREGs, Rule 20(b)) permit the use of navigation lights during periods of restricted visibility (such as fog, heavy rain, or haze) that occur during daylight hours, and also in all other circumstances when deemed necessary. Therefore, they **may be displayed during daylight** when conditions warrant increased visibility or when the operator chooses to do so for safety, even if visibility is not officially "restricted." **Explanation of Incorrect Options:** * **A) may be extinguished at night on open waters when no other vessels are in the area:** This is incorrect. Navigation lights are mandatory from sunset to sunrise regardless of whether other vessels are immediately visible. They are a required status signal, not merely an aid to collision avoidance when contact is certain. * **C) must be displayed when day signals are being used:** This is incorrect. Day signals (like shapes or flags) are used during the day in good visibility. Navigation lights (which are light sources) are specifically defined for use from sunset to sunrise and during restricted visibility. There is no rule requiring both simultaneously just because a day shape is being used (e.g., a vessel constrained by its draft displays a cylinder shape during the day, but only needs lights after sunset). * **D) must be displayed when moored to a pier:** This is generally incorrect. When a vessel is securely moored or anchored in a designated safe mooring area that is not obstructing a fairway, it typically ceases to be "underway" or "at anchor" in a navigable channel requiring mandated navigation/anchor lights. Moored vessels usually do not have to display navigation lights unless specifically required by local rules for safety or security lighting, but this is not a universal requirement under international or inland rules for basic navigation lighting.