A ship is a means of transport, a type of vessel, usually used to move on the surface of the water on the principle of Archimedes' law. For smaller vessels, the name boat is used. Ships sailing only on the surface are referred to as surface vessels, ships that allow movement even under the water surface as submersible vessels or submarines. Boats and smaller ships can be powered by oars and muscle power, but they were also powered by sails in ancient times.
Until the advent of the railway in the 19th century, shipping was the only means of transporting larger quantities of goods and raw materials, as well as the faster transport of people, especially armies. From ancient times until the beginning of the 20th century, artificial canals and canals were built for it, often supplementing the natural river network and connecting navigable rivers. With the development of automobile and air transport, the importance of passenger shipping decreased, but it still plays a large role in the transport of goods and raw materials over long distances.
In the broader sense of the word, a ship is also a means of free movement in another environment - see airship, spacecraft.
Main characteristics of ships
Purpose: sailing on rivers and lakes, short-term coastal sailing, long-term sailing on the high seas with the need for navigation.
Type: commercial, cargo, tanker, container, war, liner, cruise, recreational, fishing, special (e.g. dredger), sports, etc.
Displacement: the weight of the ship as expressed by the volume of water displaced according to Archimedes' law. It is given for a fully loaded boat up to the waterline, which is usually marked on the side of the boat. The largest cargo ships (mainly for transporting ores and coal) have a displacement of up to 400 thousand tons, tankers up to over 500. Most of them are built in Japan and South Korea.
The economy of operation plays a large role in peace and forces the construction of ever larger units. However, loading and unloading, which takes about 25 hours for a tanker, and up to 120 hours of unproductive time for a bulk carrier, remains a problem. Crashes of giant ships also worry shipowners and slowly limit the size of ships.
Length is measured at the level of the deck or waterline. It is limited on the one hand by the design possibilities, the strength of the material and, finally, by the length of the locks in the main canals. The Panama Canal allows ships with a length of about 295 m to pass through, but there are ships that have to go around Cape Horn or Cape of Good Hope.
Speed is important in warships and sport ships, whereas passenger transport has changed to pleasure cruises where it is not as important. It is measured in knots, 1 knot 1.85 km/h. Large cargo ships and tankers reach speeds of 25-28 km/h, warships and submarines up to 60 km/h. However, with increasing speed, the water resistance increases sharply, and thus the performance requirements. For higher speeds over shorter distances (typically ferries and ferries), catamarans and hovercrafts are being built, which rise up after launch and slide on the water almost without sinking.
The drive, formerly sailing, replaced the steam engine, internal combustion engine, electric motor or steam turbine with ship's screw from the mid-19th century. Submarines and large warships also use a nuclear reactor as a steam generator.
The armament of warships includes guns with a smaller caliber than the record 450 mm of Japanese cruisers, but with a significantly higher rate of fire, up to 30 rounds per minute. Not only submarines carry torpedoes and especially guided missiles with a range of up to thousands of kilometers (intercontinental missiles, ICBMs). Airplanes and helicopters are an effective weapon in conventional conflicts, but aircraft carriers are vulnerable and need additional defenses.
The defense of warships and merchant ships mainly consists of electronic devices, radars of various ranges, monitors and jammers of radio communication, throwers of deceptive targets, anti-aircraft guns and guided missiles.