What day shape accompanies a vessel that has run aground?

• A. One black ball
• B. Two black balls in a vertical line
• C. Three black balls in a line
• D. A black diamond

Answer: (C)

Day shapes are daylight signals that tell other vessels what your boat is doing so they can navigate safely. When a vessel has run aground, it can’t maneuver and may block a channel, so the standard signal is three black balls displayed in a vertical line. That arrangement is distinct and clearly communicates the grounded status to oncoming traffic, helping others plan a safe course around the vessel. Other common signals indicate different conditions—such as a single black ball for a vessel at anchor, or two black balls in a vertical line for not under command, or the ball-diamond-ball for restricted in its ability to maneuver—so the three-ball line specifically identifies grounding.