A vessel may exhibit lights other than those prescribed by the Rules as long as the additional lights

• A. Do not interfere with the keeping of a proper look-out
• B. Are not subject to any restrictions
• C. Must be yellow lights only
• D. Must be kept at a fixed intensity

Answer: (A)

Extra lighting is allowed only if it does not interfere with safe navigation, especially the ability to maintain a proper look-out. The Rules intend that the standard signals remain clear and unambiguous, so any additional lights must not obscure, mislead, or distract from those signals. In practice, a vessel can show extra lights for legitimate purposes, but they must be positioned and used so they don’t hamper other vessels’ ability to observe and interpret the prescribed lights, nor affect the lookout. That’s why this option—ensuring the additional lights do not interfere with keeping a proper look-out—is the best answer. The other statements imply no restrictions, require yellow lights only, or mandate fixed intensity, which do not align with the rules.