There are two kinds of hull materials commonly used at present: metallic materials and nonmetallic materials. metallic materials include steel, aluminum alloy, titanium alloy, etc. Non - metallic materials such as wood, composite materials.
Wood is one of the oldest hull materials. It is light in weight and has good mechanical properties, but it is prone to decay, moth and fire. Due to its structure, it is not suitable for making large ships at present.The requirement of lightweight ship and the reutilization of alloy material makes the aluminum alloy get further development in practical application. Because aluminium alloy has density small, than intensity big and do not have magnetism, high conductance and heat conduction to wait for a characteristic, at present aluminium alloy has been used in great quantities medium and small passenger ship, houseboat, speedboat, high speed missile boat, patrol boat, drive protect ship (for example the superstructure of partial warship) wait on the ship.
Titanium has only been used in the field of engineering materials for more than 50 years, but it has been quickly applied in all walks of life because of its unparalleled special properties. The reason why titanium alloy is called "Marine metal" is that it has the corrosion resistance, durability, fastness, reliability, stability and various special properties required by ship materials. However, due to the high price of titanium alloy, it cannot replace aluminum alloy and steel in a large scale, and is only used in special ship structures and parts.
Composite materials in the 1940s, the United States navy first used composite materials for ship construction, starting a new chapter of ship construction, the world began to develop a variety of composite ships. Composite materials are increasingly being used in speedboats, yachts, racing boats and small commercial fishing boats such as trawlers.
In recent years, advanced composite materials and lightweight structural technologies have become the key technologies to reduce hull weight. Composites as a new functional structure materials with light weight, than strength and high stiffness, good damping performance, fatigue resistance, creep resistance, resistance to chemical corrosion, good wear resistance, low thermal expansion coefficient, and X-ray permeability is good wait for a characteristic, is the attention of the shipbuilding industry, especially in the area of manufacturing high quality of hull structure has a huge advantage. Due to the process of no welding, no riveting, the overall weight of the ship is greatly achieved, so that the ship can easily achieve a higher speed.
The main composite materials used in the hull are carbon fiber, aramid fiber and glass fiber. There are five typical structures of composite hulls: single plate and ribbed structure, sandwich structure, hard shell structure, waveform structure and hybrid structure.
Starting with small speedboats, the use of composite materials in ships has gone through about three stages. The first stage, mainly used in minesweeper and other small ships, low performance requirements, can be formed as a whole. In the second stage, it was partially used on large and medium-sized ships, but the use concept was still limited to traditional hull design, and the composite materials only played an auxiliary role in reducing the quality and improving the corrosion resistance of the parts on the ship. In the third stage, at the beginning of the design of the ship, various complex situations faced by the use of the composite material as the main hull material, to achieve other materials can not achieve or difficult to achieve the effect. At present, Marine composite materials have broken through the second stage and developed to the third stage.