Diesel Engine Ship Era
After the advent of the diesel engine ship, it developed rapidly and gradually replaced the steam engine ship. After the end of World War II, the rapid economic recovery and development of industrialized countries, the unprecedented prosperity of international trade, and the massive development of oil in the Middle East and other places promoted the rapid development of transport ships. Compared with 1948 in 1982, the number of ships increased by 1.6 times, and the total tonnage increased by 4.3 times (see World Merchant Fleet). Ships are generally propelled by diesel engines. During the Second World War, in order to meet the needs of wartime transportation, the 2,610 Freeships (10,000-ton class general cargo ships with oil-fired boilers and steam engines) built by the United States were the last batch of ocean-going transport ships built with reciprocating steam engines. In order to improve the economic benefits of ship transportation, ships have appeared in a variety of trends such as large-scale, specialized, high-speed, automated, and internal combustion engines.
The first is the increase in the tonnage of oil tankers and the enlargement of oil tankers. In the world merchant fleet in 1930, the tonnage of oil tankers only accounted for 1/10 of the total tonnage, and it rose to 1/2 in 1980. At the beginning of 1983, the deadweight of various oil tankers reached 330 million tons. The sharp increase in the tonnage of oil tankers is mainly due to the enlargement of oil tankers. In the 1950s, oil tankers of 30,000 to 40,000 tons were considered "super tankers." In the mid-1960s, super large oil tankers of more than 200,000 tons and super large oil tankers of more than 300,000 tons appeared. In the 1970s, large oil tankers of more than 500,000 tons appeared. After the oil crisis broke out and the Suez Canal resumed navigation, this trend has stopped, and many large oil tankers are facing the fate of being demolished. While oil tankers have grown in size, there has also been an increase in the size of dry bulk carriers that carry coal, ore, and grain. At the end of the 1960s, the deadweight of large bulk carriers exceeded 100,000 tons, and the largest had reached 170,000 tons. Since the late 1950s, dual-purpose ships capable of carrying both crude oil and dry bulk have been built, such as oil bulk ships and oil bulk ships.
After the Second World War, various special ships developed rapidly. The general cargo ship has a wide range of uses and strong adaptability, and it still ranks first in the number of ships. Typical general cargo ships are powered by low-speed diesel engines, with a deadweight of no more than 20,000 tons, and a speed of about 15 knots. The cargo ships designed in China with the "Feng" and "Yang" sizes are typical general cargo ships. In order to improve the ability of general cargo ships to transport a variety of goods, multi-purpose ships have been manufactured in recent years, which can carry containers, heavy cargo, refrigerated cargo, and bulk cargo in addition to general cargo.
Waterway container transportation emerged in the mid-1950s, and the first container ship appeared in 1957. This is a major change in the form of bulk cargo transportation. This form of transportation has made breakthroughs in cargo packaging, loading and unloading technology, terminal management, and water and land combined transportation. The use of container transportation can greatly shorten the time for ships to stop at the port, save manpower, ensure the quality of freight and realize "door-to-door" transportation. For more than 20 years, container ships have developed rapidly. In 1982, there were 718 full container ships in the world with 12.94 million gross tonnage, accounting for 1% and 3% of the world's total commercial ships respectively. This kind of ship is thin and thin, has a high speed, has a guide rail in the cargo hold, and has binding equipment on the deck. Generally, there is no loading and unloading equipment, but the special port equipment is used for loading and unloading.
Important special ships developed after the Second World War include: liquefied gas ships that carry liquefied natural gas and liquefied petroleum gas; the ships are equipped with springboards that enable tractors and forklift trucks to drive up and down the ro-ro ships (also known as ro-ro ships). Drive on and off); use the barge as the transportation unit, and can realize the direct transportation between the river and the sea without the need to dock at the dock for loading and unloading.
Since ocean passenger ships were replaced by jet airliners, the nature of passenger ships has changed. Since the 1960s, tourism has risen, and there have been a number of regular, scheduled, and even circumnavigating tourist ships that provide tourists with comprehensive services such as tourism, recuperation, cultural entertainment, social activities, and marine astronomy education. At the same time, on important short-haul routes, there has also been a small tonnage car and passenger ship that can carry passengers' own cars in addition to carrying passengers.
Since the 1950s, in order to speed up the turnover of ships, the shipping industry once set off an upsurge of high-speed ships. The speed of ordinary general cargo ships has increased to 18 nautical miles per hour, and the speed of container ships is above 20 nautical miles per hour. The "SL-7" high-speed container ship built in the United States uses two 60,000 horsepower steam turbines as the main engine and has a maximum speed of 33 per hour. Nautical miles. But since the oil crisis, the proportion of fuel costs in transportation costs has soared. Forcing high-speed ships in operation to slow down one after another, the speed of newly-built ships has also shown a downward trend. However, non-displacement-type high-speed passenger ships, such as hydrofoil and hovercraft, have been used in short-distance passenger transport routes and are increasingly developed.
Since the early 1960s, in order to reduce the number of crews, improve the working conditions of crews, and increase the economic benefits of ship operations, shipping companies in various countries have gradually realized the automation of the three aspects of engineering, navigation and outfitting. For example, in the mid-1960s, ships with regular unattended engine rooms were built, which has been recognized by the classification societies of various countries.
Ship's internal combustion engine
The internal combustion of ships means that ships generally use diesel engines as their main engines. Compared with steam engines, diesel engines have the advantages of high thermal efficiency, low fuel consumption, and small footprint. Since the first diesel engine ship was built in 1911, cargo ships and passenger ships using diesel engines as the main engine have been increasing. But by the end of World War II, steam engine ships still accounted for the majority of the world merchant fleet. After the war, low-speed and high-power diesel engines, due to advances in supercharging technology, have continuously increased their single-engine power, reaching a maximum of 50,000 horsepower. Large high-speed ships that had to install steam turbines in the past can also use diesel engines. On the other hand, the adaptability of diesel engines to the use of low-quality oil has also been continuously improved, which has economic advantages. For ro-ro ships, container ships, car ferries, etc. with restricted engine room space, small and light medium-speed diesel engines can be used to drive the propellers through a reduction box. Diesel engines with low fuel consumption and different powers that can burn inferior oil now occupy almost the entire market of marine engines. Therefore, the development stage of transport ships after World War II is called the era of diesel engine ships.