Floating fender system design methods – pneumatic fender
This article mainly introduces the floating fender system design ideas and analyzes the design of the fender in various application environments. Floating pneumatic fender is an anti-collision device for ship docking with compressed air as the medium, and it is usually used in ship to ship, ship to the wharf, and wharf installations where the tide level changes greatly.
Introduction of floating pneumatic fender system
Floating pneumatic fender is an anti-collision device for ships docking with compressed air as the medium. It has the characteristics of large energy absorption, low reaction force, self-floating, and easy installation. It is usually used in ship to ship and ship to dock and other occasions; it is also particularly suitable for installation on the wharf where the tide level changes greatly.
Generally, the structure of pneumatic rubber fenders is divided into three parts: inner tank, reinforcement layer, and outer layer. The main function of the inner liner is to ensure the airtightness of the floating fender, the strengthening layer is to ensure the strength of the fender, and the outer layer is mainly for protection. In addition, larger-sized floating fenders are often equipped with a sheath composed of anchor chains and tires, which can further improve the safety and service life of the floating fender.
Floating rubber fenders were successfully developed by Japan’s Yokohama (YOKO HAMA) company as early as 1958 and were used in the sea berthing of the Japanese whaling fleet.
Floating fender system design needs to consider the following factors:
- Maximum energy absorption E;
- Reaction force;
- The distance requirements between the two ships after berthing or the ship to the dock, including the maximum distance and the minimum distance;
- The size of the ship;
- Factors such as wind, waves, and temperature changes in the actual use environment.
Among them, the distance requirement of the ship after berthing is a very important factor. After the two ships are berthed, in order to facilitate cargo handling operations, there is a requirement for the distance between the two ships (standoff), so the maximum diameter of the designed floating fender cannot exceed this distance.
However, when two ships collide, the minimum distance is often required. This minimum distance determines the maximum working height of the floating fender. When two ships are berthing, if one of the ships is equipped with protrusions such as brackets, there is a minimum distance requirement in this case. If the minimum distance is greater than the working height when the selected floating fender is compressed by 60%, the maximum working height of the fender should be calculated based on the minimum distance instead of the usual 60%.
How to choose the suitable floating fender system
Compared with other types of fenders, the reaction force of floating fenders is very small. Usually, the reaction force acting on the ship’s side or wharf is within the allowable range. In principle, two floating fenders should be used as anti-collision points for berthing between two ships. For larger ships, one or two floating fenders should be added to improve the safety of the system.
The design of the floating fender system first needs to determine the collision energy of the ship when and after berthing, and select the specifications of the floating fender according to the distance requirements (maximum distance and minimum distance) after berthing, and verify the floating fender at the same time Whether the maximum reaction force is within the allowable range of the hull design. If it is necessary to increase the energy absorption of the floating fender, increasing its diameter is an ideal choice. The number and spacing of floating fenders are determined according to the size of the ship and actual use.