Question 23 RVR01 - Master of Unlimited Tonnage

The Correct Answer is C 1. **Why option C ("a vessel of special construction") is correct:** Rule 21(a) (Definitions) and Rule 2(b) (Responsibility) are relevant here. Specifically, Rule 21(a) defines the masthead light. However, the authority for displacing lights comes from **Rule 3(l)** (General Definitions) and **Annex I, Section 3(b)** (Positioning and Technical Details of Lights and Shapes). Annex I, Section 3(b) states: "If it is impracticable to comply with the requirements of paragraph (a) of this section [concerning the placement of lights on the centerline] by reason of the special construction of the vessel, the masthead light or after masthead light need not be placed in the fore and aft centerline of the vessel provided that the measures adopted or the arrangement are such as to indicate the vessel’s fore and aft axis." This exemption applies internationally (COLREGs) and therefore applies to inland waters as well, making "a vessel of special construction" the correct answer. 2. **Why the other options are incorrect:** * **A) a vessel engaged in trolling:** Trolling is a type of fishing. While fishing vessels have specific lighting requirements (Rule 26), there is no general exemption based solely on the activity of trolling that allows the masthead light to be off the centerline. Standard fishing vessels must adhere to the centerline placement requirements unless they qualify under the special construction exemption. * **B) a power-driven vessel 12 meters in length:** Small power-driven vessels (under 50m) must display a masthead light (Rule 23). Their length (12m) does not grant them an exemption from the requirement that the masthead light must be on the fore and aft centerline (Annex I, 3(a)). * **D) an air-cushion vessel in non-displacement mode:** An air-cushion vessel (ACV) operating in non-displacement mode (on cushion) has specific lighting requirements (Rule 23(b) – an all-round flashing yellow light). However, this rule does not override the requirement that the masthead light (when required) must be placed on the centerline, unless the vessel also qualifies as being of "special construction." The mere fact of being an ACV in non-displacement mode does not, by itself, permit displacement of the masthead light.