The lightweight structure of the ship's superstructure not only reduces the mass of the hull, increases the speed or capacity of the ship, but also rationalizes the structure of the ship and improves the relationship between the stability of the hull and the displacement and the width of the ship.
The biggest problem affecting people living at sea is the lateral stability of the ship, which is determined by the height of the center of the tilt. To ensure a certain fixed tilt center height, the ship should have sufficient width. In order not to make the ship particularly wide, it is necessary to reduce the quality of the ship's superstructure, reduce the center of the ship, and increase the height of the fixed tilt center to make the ship laterally stable.
At present, more and more
marine grade aluminum plate is used for the superstructure of the various types of ships and other devices on the upper part (mast, chimney, gunboat's base).such as: marine grade aluminum 5086 , marine grade aluminum 6061. The upper structure of the ship was first riveted with rivets, and the welding method was mainly used after the 1970s. The deformation of the thin plate is deformed, and it is most desirable to use the integrally extruded wall plate as the upper structure.
On the "Kyrgyzstan" ocean liner, the former Soviet Union used aluminum alloys to build superstructures such as cockpits, masts, chimneys, skylights, watertight doors and windows. The 5.6mm and 8mm thick marine grade aluminum 5052 and the 10mm and 14mm thick
marine grade aluminum 5083 are used. Round head flat aluminum, also used some aluminum alloy castings. The longitudinal and transverse bulkheads are made of aluminum alloy corrugated sheets. The upper structure was riveted to the steel deck with 5A05 aluminum alloy rivets, and measures to prevent contact corrosion were taken.
The aluminum alloy superstructure of the "Kyrgyzstan" ocean-going passenger ship is 50% lighter than the steel (140t weight loss). The ship's center of gravity is low, the draft is shallow, and it can enter the estuary. The length of the ship is 101.5m, the width is 14.6m, the height is 8.1m, the water line is 3.7m, the displacement is 2960t, the passengers are 250 people, the crew is 76 people, and the sailing speed is 30km/h. In this ship, 175t of aluminum is used (100t for the upper structure). The total mass of the ship was reduced by 12%, and the height of the fixed center of gravity was increased by 15 cm, which significantly improved the stability of the ship.
The "Canaberra" regular ocean liner, built in Britain in 1960, has a displacement of 45,000 tons and uses 1000 tons of aluminum. The “Orlana” has a displacement of 40,000 tons and is made of 1040t aluminum. The "French" ocean liner built in France also uses aluminum as the upper structure, and the mast and chimney are also made of aluminum, sharing 750t. Not only does it reduce the mass of the ship's upper part, the total mass of the ship is reduced by 15%, the width of the ship is reduced compared to the original steel, and its stability is not lost. Compared with the "Normandie" steel ship of comparable performance, the speed of navigation and the number of passengers have increased.