Question 23 RVR05 - Master of LT 100 GRT

The Correct Answer is C. ### Why Option C is Correct: The rule governing the placement of lights (specifically the masthead light) is found in the **COLREGs Annex I, Section 3(a)** (Positioning and Technical Details of Lights and Shapes). This section specifies that lights must be positioned on the vessel's centerline, but it provides an exception. **COLREGs Annex I, Section 3(a)** states: "The masthead light, or if there is more than one, one of them, **shall be placed forward of the all-round lights and shall, except as provided in sub-paragraph (b)**, be placed in the fore and aft centerline of the vessel." **COLREGs Annex I, Section 3(b)** then provides the exception for the displacement of lights: "On **vessels of special construction or design** where it is impracticable to carry the masthead light(s) in the fore and aft centerline, they may be carried **otherwise than in the fore and aft centerline**, provided that the positioning provides an equivalent degree of visibility." Therefore, a vessel designated as being of "special construction" (such as certain types of survey vessels, icebreakers, or unique naval vessels) is the only category explicitly permitted by the rules to displace the masthead light from the centerline due to structural impossibility. ### Why the Other Options Are Incorrect: **A) a vessel engaged in trolling:** A vessel engaged in trolling is typically displaying fishing lights (green over white all-round lights) but must still carry its mandatory navigation lights, including the masthead light, on the centerline unless it meets the special construction exemption. The nature of its operation does not waive the centerline requirement. **B) a power-driven vessel 12 meters in length:** A standard power-driven vessel of any length, including one 12 meters or less, is required to place its masthead light(s) (or combined lantern) on the centerline as per the general rule. There is no exemption for small size alone. **D) an air-cushion vessel in non-displacement mode:** An air-cushion vessel (hovercraft) operating in non-displacement (flying) mode is required to display specific additional lights (an all-round yellow flashing light), but the placement of its mandatory masthead light must still conform to the centerline requirement, unless it also happens to be a vessel of special construction (which is a separate designation from its operational mode). Its operational status does not automatically grant exemption from the centerline rule.