Day shapes

Day shapes are mast head signals visually indicating the status of a vessel to other vessels on navigable waters during daylight hours whether making-way, anchored, or aground. These signals consist of a set of simple geometric shapes: ball, cylinder, cone, and diamond that are displayed, hung from a mast, in a prescribed manner to indicate a vessel's operational status; some of these signals maybe somewhat involved. The meanings of the shapes are defined by the International Regulations for Preventing Collisions at Sea.