Question 18 OSV01 - Master/Chief Mate - Offshore Supply Vessels

The Correct Answer is A. **Explanation for A (A vessel constrained by her draft):** Rule 28 of the COLREGs specifies the lights for vessels constrained by their draft (CBD). A CBD vessel, in addition to the lights required for a power-driven vessel of her length, must display **three all-round red lights in a vertical line** where they can best be seen. These three red lights signify that the vessel's ability to maneuver is restricted by the shallow depth of the water (draft). **Explanation for why other options are incorrect:** **B) A vessel moored over a wreck:** A vessel engaged in minesweeping operations displays three all-round green lights, but a vessel simply moored over a wreck does not have a specific COLREG signal of three vertical red lights. A vessel engaged in diving or underwater operations might display the signals specified for a vessel restricted in its ability to maneuver (RIM), which are red-white-red vertical all-round lights, but not three red lights. **C) A vessel aground:** A vessel aground must display the lights required for a vessel at anchor (two all-round white lights, fore and aft), and in addition, **two all-round red lights in a vertical line** where they can best be seen. It displays two red lights, not three. **D) A vessel dredging:** A vessel engaged in dredging (which is classified as a vessel restricted in its ability to maneuver, or RIM) displays different signals depending on the operation: * Three all-round lights in a vertical line: Red-White-Red (RIM signal). * When restricted by the operation, it also shows two all-round red lights in a vertical line on the side where the obstruction exists and two all-round green lights on the side where it is safe to pass. It does not display three all-round red lights in a vertical line as its primary identification signal.