What is the day shape indicating RAM status?

• A. Ball.
• B. Two black balls.
• C. Diamond.
• D. Ball-Diamond-Ball.

Answer: (D)

In COLREGs, day shapes tell others what kind of maneuvering limitations a vessel has. When a vessel is restricted in its ability to maneuver, the required day shapes are three symbols shown in a vertical line: a filled ball at the top, a filled diamond in the middle, and a filled ball at the bottom. This ball-diamond-ball arrangement immediately signals to approaching vessels that this vessel cannot help avoid a collision as readily as others and that others should take early and substantial action to keep clear.

Other statuses use different shapes: a single filled ball means not under command, and a single diamond means constrained by draft. So the ball-diamond-ball sequence specifically identifies the RAM (restricted in ability to maneuver) status.