Dry bulk cargoes such as coal, grain and ore were previously transported by ordinary cargo ships. With the development of ship specialization, special iron ore carriers appeared in the early 20th century, and self-unloading ore carriers appeared in 19 12. Until World War II, bulk cargo owners mainly developed with ore ships and coal ships. After World War II, cement, fertilizer, sawdust and sugar also began to be transported in bulk, and the application scope and fleet size of bulk carriers expanded rapidly. The number of bulk carriers in the world has increased from 1 in 1954 to 1 167000 dwt (of which ore ships account for 70%) to1871kloc-0/00000 dwt. Since then, the number of bulk carriers has increased at a faster rate. During the 30 years from 1960 to 1990, the number of bulk carriers increased by 9.8 times and the deadweight tonnage increased by 27 times. 1990 the number of bulk carriers has reached 5087 and 242.55 million dwt. According to Lloyd's Register of Shipping, at the end of 2003, the number of bulk carriers in the world was 5888, 307 1 10000 dwt, with an average age of 14.5 years.

During the five years from 1960 to 1975, the number of bulk carriers increased sharply. In the first half of 1980, the number of bulk carriers increased rapidly, which was contrary to the rapid decline of tanker tonnage, but during the period of 1986 ~ 1994, the number of bulk carriers decreased, and then showed a steady growth trend. Generally speaking, among the four types of ships, namely oil tankers, bulk carriers, container ships and general cargo ships (including multi-purpose cargo ships) since 1980, container ships have developed the fastest, and bulk carriers have also increased rapidly. In recent years, the tonnage of oil tankers has been declining slowly, while that of general cargo ships (including multi-purpose cargo ships) has been declining continuously.

Large-scale process: another feature of the development of bulk carriers is the large-scale ship. 1954, the average tonnage of bulk carriers was only 19000 dwt, which has exceeded 40000 dwt since 1973, and now it has reached 54000 dwt. The increase of the average tonnage of bulk cargo fleet is mainly reflected in the increase of Panama-type 60,000-80,000 dwt, Cape of Good Hope-type 654.38+20,000-200,000 dwt and handy-type 40,000-60,000 dwt, while the number of ships below 40,000 dwt has obviously decreased. At the same time, the average tonnage of all kinds of bulk carriers is also on the rise. According to the statistics of a maritime information service company, the average tonnage of bulk carriers in Cape of Good Hope in190 was 1294 15dwt, which increased to 16 1088 dwt in 2003. During the same period, the average tonnage of Panamanian bulk carriers increased from 64,294 dwt to 69,970 dwt. Among them, due to the limitation of Panama Canal width, Panama-type bulk carriers only increased by 5,376 dwt in 13, which was much lower than that of Cape of Good Hope (increased by 3 1.673 dwt). There are three main factors to promote the large-scale bulk carrier, namely, the economy of large ships is better; The continuous improvement of ship design and construction level; Expand the port scale and improve facilities.