Which rule addresses the use of day shapes to indicate a vessel's status?

• A. Rule 5 Look-out
• B. Rule 8
• C. Rule 3 (General Definitions) and related rules for Not Under Command, RAM, and other statuses.
• D. Rule 19 Head-on

Answer: (C)

Day shapes are a signaling method used to convey a vessel’s status to other mariners. In the COLREGs, Rule 3 (General Definitions) and the related rules define these statuses—such as Not Under Command and Restricted in Ability to Maneuver (RAM)—and specify the day shapes to be displayed for each status. That makes this rule set the authoritative reference for how and when to show day shapes.

The other rules mentioned focus on collision avoidance actions (Rule 8) or specific meeting situations (Rule 19) and do not prescribe the signaling shapes themselves. So Rule 3 and its related rules are the ones that address the use of day shapes to indicate a vessel’s status.