What shape is typically used for north cardinal buoys?

North cardinal buoys are characterized by their distinctive shape, which consists of two upward-pointing triangles. This design signifies that the safe water is to the north of the buoy. The triangular shapes on the buoy are a critical aspect of the IALA (International Association of Marine Aids to Navigation and Lighthouse Authorities) system, as they convey vital navigational information to mariners.

The use of two triangles not only enhances visibility but also helps distinguish north cardinal buoys from other types of buoys in the system. The color scheme—often black above and yellow below—also contributes to their identification, but the shape is a key feature that mariners rely on to navigate safely and effectively. Understanding this specific characteristic helps in recognizing and interpreting buoys correctly while at sea.