Question 11 GLI08 - Limited OUPV

The Correct Answer is A Option A ("do not impair the visibility or distinctive character of the prescribed lights") is correct because it directly reflects the requirement set forth in the International Regulations for Preventing Collisions at Sea (COLREGS), Rule 20(b) and related rules concerning the exhibition of lights. Specifically, Rule 20(b) states that additional lights, such as signal lights, must not be exhibited in such a way that they obscure or interfere with the visibility or distinctive character of the required navigational lights, nor distract from the keeping of a proper look-out. This is the fundamental safety standard for any non-prescribed lights. **Why the other options are incorrect:** * **Option B (are not the same color as either sidelight):** While prudence dictates avoiding confusion with prescribed lights (red, green, white, yellow/all-around white for towing/fishing, etc.), there is no blanket rule prohibiting the use of certain colors for *non-navigational* purposes (e.g., deck lighting, floodlights, or certain required signaling lights if authorized). The primary safety concern is *impairment*, not merely color similarity, though confusing colors are implicitly covered by the impairment rule. However, the rule itself is framed around impairment, making A the definitive and direct requirement. * **Option C (have a lesser range of visibility than the prescribed lights):** This is incorrect. There is no specific requirement that additional, non-prescribed lights (such as searchlights or decorative lights) must have a *lesser* range of visibility than the prescribed navigational lights. The focus is solely on ensuring they do not obscure or degrade the required lights (Option A). An additional light having a greater range of visibility is acceptable as long as it meets the condition in A. * **Option D (All of the above):** Since options B and C are incorrect, D is also incorrect.