Buoys can be divided into sea buoys and inland river buoys according to the waters laid. The basic shapes of ocean buoys are trough, cone, cylinder and rod. Due to the influence of wind, waves and tides, the buoy has a certain Yves range, so it can not be used as a symbol to determine the position of the ship. If the articulated rod buoy is used, the position is accurate and can be reset after being hit. Inland river buoys include drum buoys, triangular buoys, rod buoys, cross-flow buoys and left and right navigation buoys. The shape, color, top mark and light color of the buoy are all made according to the prescribed standards, and they all have certain meanings.
In 197 1, the technical committee of the International Association of Navigation Aids divides all kinds of marine buoys into two systems, A and B. System A is a combination of side marker (red on the left side faces port) and azimuth marker. System B is a side sign system (red with the right side facing the port side). 1980 The 10th International Conference on Navigation Aids merged the A and B systems into a unified system, including five types of signs, such as side signs, azimuth signs, isolated dangerous goods signs, safe water signs and special signs. The content of lateral sign is opposite in system A and system B, while the other four symbols are the same. The azimuth marker is to set the north coordinate, the east coordinate, the south coordinate and the west coordinate in the four quadrants of the true azimuth centered on dangerous objects or dangerous areas, that is, northwest to northeast, northeast to southeast, southeast to southwest, southwest to northwest, so as to mark the navigable waters on the same side of the azimuth marker. The sign of isolating dangerous goods is set on or as close as possible to dangerous goods, indicating that ships should avoid sailing. Safe waters signs are set in the center or midline of the waterway, and navigation can be carried out around the signs. Special signs are used to mark specific waters or features, such as quarantine anchorage, no-fly zone and offshore operations.
European countries, African countries and the Gulf region, as well as some Asian countries, Australia and New Zealand adopt system A, which is called area A; American countries, Japan, South Korea and the Philippines adopt system B, which is called area B. China adopts a system.