Sea transport (or Ocean Transport) is the most commonly used and most common mode of international cargo transportation. The cargo transportation volume of ocean transport accounts for about 80% of the total international trade cargo transportation volume. The reason why ocean transport is widely used is that compared with other modes of transportation, it has the following three outstanding advantages.
(1) Large carrying capacity. The carrying capacity of ocean-going ships far exceeds that of trains, cars, airplanes, etc. At present, the carrying capacity of oil tankers has reached 600,000 tons, and that of bulk carriers has reached more than 300,000 tons. Some ships can carry more than 4,000 standard containers. Therefore, the carrying capacity of a 10,000-ton ship is generally equivalent to the carrying capacity of 250 to 300 train cars.
(2) Low freight. Due to the large carrying capacity, it has better economies of scale and fuel factors. Therefore, the unit freight of ocean transport is much lower than other modes of transportation. The cost of transporting each unit of goods by ocean transport is only about 1/20 of that by rail transport and about 1/30 of that by air transport.
(3) Strong throughput capacity, not restricted by tracks and roads. Ocean transport can make use of the extensive natural waterways and is not easily restricted. It is not restricted by tracks and roads like trains and cars.
Although ocean transport has the above advantages, it also has its shortcomings. For example, ocean transport is easily affected by climate and natural conditions, so it is difficult to accurately determine the sailing date and the risks during navigation are relatively high; for example, natural disasters, accidents, pirate plunder, military conflicts or economic sanctions. The sailing speed is also relatively slow and the transportation period is long: for example, the current ocean-going cargo ships generally have a speed of 10 to 20 kilometers per hour (18.52 to 37.04 kilometers), and it takes about 20 to 30 days to transport goods from China to Europe and the United States. It involves many parties and complex legal relationships.