Question 25 ONC06 - Master LT 100 GRT

The Correct Answer is B **Explanation for Option B (Correct Answer):** The placement of navigation lights is governed by the rules of the road (specifically, the Inland Navigational Rules Act of 1980 or US Inland Rules, which mirror COLREGs in many aspects). Rule 21(a) and Annex I (Positioning and Technical Details of Lights) provide the detailed specifications. For power-driven vessels **less than 12 meters (39.4 feet) in length**, the rules allow for greater flexibility in the placement of the masthead light (or all-round white light, which serves as the masthead light for this size category). Specifically, Annex I, Section 3(b) states that on a vessel of less than 12 meters in length, the masthead light need not be placed in the fore and aft centerline if it is impracticable to do so, provided that the location chosen is as close as possible to the fore and aft centerline. This flexibility recognizes the size constraints and design limitations of very small vessels, making **less than 12 meters in length** the determining factor for permitting off-center placement. **Explanation of Incorrect Options:** **A) which has separate sidelights carried on the outboard extremes of the vessel's breadth:** While vessels with a length of 20 meters or more are required to place their sidelights near the outboard extremes, this placement is related to breadth requirements, not the mandated positioning of the masthead light along the fore and aft centerline. Sidelight placement does not grant permission for the masthead light to be off-center. **C) engaged in fishing:** A vessel engaged in fishing displays specific lights (two all-round lights, red over white), but its designation as "engaged in fishing" does not automatically exempt it from the centerline placement requirement for its mandatory masthead light (when required to display one, e.g., when making way). The exception for off-center light placement is based on vessel *size* (less than 12 meters), not *activity*. **D) less than 20 meters in length:** While vessels less than 20 meters long have some alternative lighting arrangements (e.g., they may combine sidelights in one lantern), the critical threshold for permitting the masthead light to be located *off* the fore and aft centerline due to impracticability is specifically **less than 12 meters**, not less than 20 meters. Vessels between 12 meters and 20 meters generally must adhere strictly to the centerline placement requirements, unless specific exceptions for certain structures apply (which is rare).