Daymark

A daymark is a navigational aid for sailors and pilots, distinctively marked to maximize its visibility in daylight.

[1] The word is also used in a more specific, technical sense to refer to a signboard or daytime identifier that is attached to a day beacon or other aid to navigation.

[2] In that sense, a daymark conveys to the mariner during daylight hours the same significance as the aid's light or reflector does at night.

[3] Standard signboard shapes are square, triangular, and rectangular, while the standard colours are red, green, orange, yellow, and black.

[2] Chart symbols used by the US National Oceanic and Atmospheric Administration Department, 2013.