What does "daymark" refer to in the context of a buoy?

A "daymark" refers to a non-lighted visual identifier designed explicitly for daytime navigation. These markings on buoys aid mariners by providing a recognizable shape, color, or symbol that is easily visible during daylight hours. The purpose of a daymark is to assist in the safe navigation of vessels in areas where visibility is good, offering a way for navigators to identify specific locations or marks on the water.

In contrast, lighted signals serve the purpose of guiding vessels at night; therefore, they are not applicable in a daytime context. Radar reflections, while useful for navigation in poor visibility conditions such as fog, do not constitute what is defined as a daymark. Additionally, navigational chart symbols contribute to map reading and planning but do not provide the physical, visual identification associated with a buoy. Thus, the defining feature of a daymark relates directly to its function of being a visual marker during daylight hours.