Question 23 RVR02 - Master of LT 500-1600 GRT

The Correct Answer is C. ### Why Option C is Correct: **C) a vessel of special construction** This option is correct based on the **International Regulations for Preventing Collisions at Sea (COLREGs), Annex I, Section 3 (Positions and Technical Details of Lights and Shapes).** Specifically, **Annex I, Section 3(a)** addresses the practical difficulties in placing lights on certain vessels: > "The horizontal and vertical separation of the lights shall be as generally specified in this Annex and as closely as possible to the requirements of this Annex. **Such placement shall be maintained in all conditions of operation except that, on a vessel of special construction or purpose, if it is not possible to comply fully with the requirements for the horizontal and vertical separation of masthead lights as herein prescribed, the lights shall be placed in such positions as will best comply with these requirements.**" While this section primarily discusses separation, the general intent and accepted interpretation for vessels where strict compliance is impossible (such as those with extremely wide decks or specialized gear fixed permanently on the centerline) allows for displacement of the masthead light from the centerline if structurally necessary, provided the displacement is minimized and clearly documented as a vessel of "special construction or purpose." Furthermore, **Annex I, Section 5 (Screening of Sidelights by Superstructure)** indirectly supports this concept by addressing vessels where conventional placement is impossible: > "If the masthead light is displaced from the centerline, the sidelights shall be placed in the fore and aft line of the masthead light or in a position as nearly as practicable to the fore and aft line." This explicitly acknowledges that the masthead light *may* be displaced from the centerline on certain vessels, aligning with the allowance for vessels of special construction where the standard centerline placement is structurally or functionally impossible. ### Why Other Options Are Incorrect: **A) a vessel engaged in trolling** A vessel engaged in trolling is typically displaying fishing lights, but it is not inherently exempt from the standard centerline placement requirement for its masthead light simply because of the operation it is performing. Unless the vessel is also certified as one of special construction, the standard rules apply. **B) a power-driven vessel 12 meters in length** A power-driven vessel under 20 meters (including one 12 meters in length) has simplified lighting requirements but is still required, where practicable, to keep the masthead light on the centerline. The small size does not automatically grant an exception to displace the light from the centerline. **D) an air-cushion vessel in non-displacement mode** An air-cushion vessel (hovercraft) operating in displacement mode (floating like a conventional vessel) uses standard lighting. When operating in non-displacement mode (on the cushion), it uses standard lights *plus* an all-round yellow flashing light. However, the requirement for standard masthead lights to be on the centerline still applies unless the vessel is also certified as one of special construction. The mode of operation itself is not the source of the displacement allowance.