Question 25 ONC01 - Master/Chief Mate Unlimited Tonnage

The Correct Answer is B **Explanation for Option B (less than 12 meters in length):** The placement of the masthead light is governed by navigational rules (specifically Rule 21(a) regarding definitions, and Rule 23 regarding power-driven vessels underway). Rule 23 requires that the masthead light be placed "in the fore and aft centerline" of the vessel. However, for smaller vessels, certain relaxations or special provisions are allowed. Annex I, Section 3(b) of the COLREGs (Inland and International) provides specific relief regarding the location of lighting fixtures for vessels less than 12 meters in length. It states that if it is impracticable to place the masthead light (or the all-round light used in place of the masthead light) on the fore and aft centerline, it may be offset from the centerline, provided that the structural limitations or configuration of the vessel require it and that the offset position causes no interference with the required sector visibility of the light. Therefore, a power-driven vessel less than 12 meters in length is the specified category where the masthead light is explicitly permitted to be located *other than* on the fore and aft centerline due to practical limitations. **Explanation of Incorrect Options:** **A) which has separate sidelights carried on the outboard extremes of the vessel's breadth:** While sidelights being carried on the outboard extremes is an option for vessels less than 20 meters (Rule 23(c)(iii)) or those where they must meet specific placement criteria (Annex I, 3(a)), this placement rule relates only to the sidelights and has no bearing on the mandated centerline placement of the masthead light for most vessels, regardless of size or sidelight arrangement. **C) engaged in fishing:** Vessels engaged in fishing (Rule 26) are defined by the lights they display (two all-round lights, vertical line, green over white), not by a special exemption allowing the masthead light (if carried) to be offset from the centerline. Fishing vessels generally must still adhere to standard placement requirements for their masthead light (if they carry one) unless they fall under the "less than 12 meters" exemption. **D) less than 20 meters in length:** While vessels less than 20 meters receive some lighting concessions (such as combining the masthead light and stern light into a single all-round white light, or only requiring one masthead light), the general requirement for any carried masthead light to be placed on the fore and aft centerline applies to all vessels up to 20 meters (and above), unless they meet the specific exception for vessels *less than 12 meters* in length (Option B).