Classification of ships

There are many classification methods for ships, which can be classified according to use, sailing state, number of hulls, propulsion power, and propellers.

According to the purpose, ships are generally divided into two categories: military and civilian ships. Military ships are usually called ships or warships, and those with direct combat capability or sea area protection capability are called combat ships, such as aircraft carriers, destroyers, frigates, missile boats and submarines, as well as minelaying and minesweeping ships[2], etc., responsible for logistics support Called military auxiliary ships. Civil ships are generally divided into transport ships, engineering ships, fishing ships, port ships and so on.

According to the sailing state of the ship, it can usually be divided into displacement ships, planing boats, hydrofoils and hovercraft;

According to the number of hulls of the ship, it can be divided into monohull and multihull, among which catamaran is more common;

According to the propulsion power, it can be divided into motor ships and non-motor ships. According to the type of propulsion main engine, motor ships can be divided into steam engine ships (now eliminated), steam turbine ships, diesel engine ships, gas turbine ships, combined power plant ships, electric propulsion ships, nuclear power boats, etc.;

According to the ship's propeller, it can be divided into propeller ship, water-jet propulsion ship, jet-propelled ship, paddle steamer, flat-rotating steamer, etc. Air propellers are only used for a few hovercraft; According to the hull structure materials, there are steel boats, aluminum alloy boats, wooden boats, steel mesh cement boats, fiberglass boats, rubber boats, mixed structure boats, etc.

According to nationality, it is divided into national ships (referring to ships registered in China and flying domestic flags) and foreign ships (referring to ships registered in foreign countries and flying foreign flags).

According to the voyage distance, it is divided into offshore ships and ocean-going ships. The sailing capabilities of the two are different.

The main technical characteristics of the ship include the displacement of the ship, the main dimensions of the ship, the number of the hull, the cabin capacity and registered tonnage, the hull line diagram, the general arrangement of the ship, the hull structure diagram, the specifications of the main technical equipment, etc.

According to Archimedes' principle, the weight of the water displaced below the waterline of the hull is the buoyancy of the ship, and should be equal to the total weight of the ship. The dead weight of the ship is equal to the displacement of the empty ship. The sum of the ship's own weight plus the weight of the various loads loaded onto the ship (dead weight) varies, i.e. equals the total weight of the ship.

The deadweight of the ship includes the weight of cargo, fuel oil and lubricating oil, fresh water, food, personnel and luggage, spare parts and supplies, etc. Usually the sum of the predetermined design cargo capacity and the weight of oil, water, food, etc. calculated according to the predetermined maximum voyage is called the design cargo capacity. The displacement at the design load capacity is called the design displacement or the full load displacement.

The main dimensions of the ship include overall length, design waterline length, length between vertical lines, maximum ship breadth, moulded breadth, moulded depth, full load (design) draft, etc. The measurement of the main dimensions of the steel ship refers to the size measured to the inner surface of the hull plate, which is called the moulded width and the moulded depth, and the cement ship, wooden ship, etc. refer to the dimension measured to the outer surface of the hull.
Tank capacity refers to the volume of cargo tanks, fuel tanks, water tanks, etc. It characterizes the ship's loading capacity and endurance in terms of accommodation capacity, and it affects the ship's operating capacity. Registered tonnage is a metric left over from history to measure the loading capacity of ships, and is one of the basis for buying and selling ships, paying taxes, and charging for services. Registered tonnage and deadweight reflect the holding capacity of the cabin and the load-bearing capacity of the ship, respectively. Although they are related to each other, they are different concepts.

The hull line drawing is the shape and size of the surface of the main body of the ship (including the bulwark, the forecastle and the poop), and it is one of the main drawings for the design and construction of the ship. It consists of three sets of line graphs: horizontal section, half-width waterline and vertical section. The three are respectively cut from the transverse section, the waterline plane and the longitudinal section and the hull surface.

The general design drawing of the ship is one of the main drawings for the design and construction of the ship, which reflects the architectural features, shape and size of the ship, the location and internal arrangement of various cabins, the arrangement of internal staircases, and the layout of deck equipment. The general arrangement plan consists of side view, plan of each deck and division of double bottom tanks.

The hull structure diagram reflects the structure of each part of the hull, and the structures of the relevant parts of the hull are both independent and interrelated. The main structure of the ship is the key to ensure the longitudinal and transverse strength of the ship. It is usually designed as a hollow beam, and the size and specification of its components are reflected by the midship transverse section structure diagram.

By purpose
-Passenger ships : Ships for transporting passengers.
-Cargo Ship : Ship for cargo transportation. Such as oil tankers, bulk carriers, container ships, etc.
-Cargo and Passenger Ships: Ships for both cargo and passenger transport.
- Rescue operation boat: used for marine rescue work.
-Engineering ships: salvage ships that deal with salvage and other work, scientific research ships engaged in scientific research and investigation work, and engineering ships that perform maintenance and repair work on ships in flight. fall into this category.
- Refers to a sailing vessel: a vessel that specifies a channel.
- Fishing boats : boats used in the fishing industry.
-Speedboat : A boat mainly used for water entertainment, or rowing competition. There are many types of motorboats, and hovercraft belong to this type.
-Military ships: ships of military use, such as cruisers, destroyers, submarines, etc., military ships whose ships themselves are not used for military use are also classified in this category.

By material
According to the budget, more than 1,000 kinds of materials and more than 5,000 tons of steel are needed to build a 10,000-ton ship.
-Steel boat
- wooden boat
-Alloy boat
-Fiberglass boat
-Cement boat

Sort by material
- Monohulls, multihulls (catamarans, trimarans, etc.). The general common boat is a monohull. The catamaran has two slender hulls. It uses a turbojet engine to get the reaction force by spraying water backwards to propel forward faster than ordinary propellers. At high speeds, the catamaran The slender hull reduces drag. And the hull is stable and not easy to capsize. Often used in ferries and military transport.
-Hydrofoil This is a ship that can sail at high speed. There are brackets on the bottom of the boat, and hydrofoils are installed. When the boat accelerates, the hydrofoils can generate buoyancy to lift the hull out of the water, thereby reducing the resistance of the water and increasing the sailing speed.
-Hovercraft Hovercraft is a kind of boat that can sail at high speed, using air to support the bottom pad to reduce the resistance of water. Many hovercraft can go over fifty knots.

By power
- Hovercraft: The air above atmospheric pressure is used to form an air cushion between the bottom of the ship and the supporting surface, so that all or part of the hull is separated from the supporting surface and sails at high speed.
-Human-powered boat/Animal-powered boat : Power is generated by manpower, using oars, etc.
-Sailboat: Use the wind to blow the sail to generate power.
-Sailboats : wind-powered, twin-engined boats.
-Ship : Engine powered boat.
-Nuclear Powered Ships: Ships that use nuclear reactors to generate power.