Question 18 ONC03 - Master LT 500-1600 GRT

The Correct Answer is A. **Explanation for A (A vessel constrained by her draft):** Rule 28(b) of the International Regulations for Preventing Collisions at Sea (COLREGs) specifies the lights for a vessel constrained by her draft. Such a vessel must show, in addition to the lights prescribed for a power-driven vessel underway (masthead lights, sidelights, and sternlight), **three all-round red lights in a vertical line** where they can best be seen. Therefore, sighting three red lights in a vertical line dead ahead at night indicates a vessel constrained by her draft. **Explanation for Incorrect Options:** **B) A vessel moored over a wreck:** A vessel engaged in diving or rendering service to a wreck is restricted in its ability to maneuver. A vessel engaged in these activities would typically display three all-round lights in a vertical line (red, white, red) to indicate it is a vessel restricted in its ability to maneuver (Rule 27(b)), or specific shapes/lights if divers are deployed (Rule 27(d)). It would not display three all-round red lights. **C) A vessel aground:** A vessel aground displays the lights prescribed for a vessel at anchor (an all-round white light forward and/or aft, depending on length) and, in addition, **two all-round red lights in a vertical line** where they can best be seen (Rule 30(e)). It displays two red lights, not three. **D) A vessel dredging:** A vessel engaged in dredging is a type of vessel restricted in its ability to maneuver. It displays the lights prescribed by Rule 27(b), which includes three all-round lights in a vertical line (red, white, red) to indicate restricted maneuverability. Additionally, it displays lights/shapes indicating the side on which obstruction exists (two vertical red lights/balls) and the side on which it is safe to pass (two vertical green lights/diamonds). It does not display three vertical red lights alone to signify its status.