Question 18 ONC05 - Master or Mate of LT 200 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 shall exhibit, in addition to the lights prescribed for a power-driven vessel underway: 1. Three all-round red lights in a vertical line. 2. When underway, the masthead lights, sidelights, and sternlight. The sighting of three red lights in a vertical line, dead ahead at night, is the unique signal indicating a vessel constrained by her draft (V.C.B.D.). **Explanation of Incorrect Options:** **B) A vessel moored over a wreck:** A vessel engaged in diving operations or mooring over a wreck, if not constrained by the operation, would typically display lights indicating a vessel restricted in her ability to maneuver (three all-round lights: red, white, red, in a vertical line). If she is simply moored, she would display anchor lights, not three red lights. **C) A vessel aground:** Rule 30(d) states that a vessel aground shall exhibit the lights for a vessel at anchor (forward all-round white light, or two if over 50 meters) and, in addition, two all-round red lights in a vertical line where they can best be seen. This is only **two** red lights, not three. **D) A vessel dredging:** A vessel engaged in dredging operations is considered a vessel restricted in her ability to maneuver (Rule 27). Such a vessel exhibits three all-round lights in a vertical line (red, white, red). If an obstruction exists, she also displays two all-round red lights on the side of the obstruction and two all-round green lights on the side on which another vessel may pass. In no configuration does a dredging vessel display three all-round red lights alone.