1. Ship overload

This kind of damage often occurs in the rubber fender, especially some old rubber fender, often cracking in the thin part of the structure. Cracks are usually in the direction of the length of the rubber fender. Type D and type V fenders are more common. The secondary cause of the rubber fender cracking is that the kinetic energy of the ship striking the fender is too large, which crosses the load that the rubber fender can accept. The cause of the excessive kinetic energy of ship collision is that the speed and Angle of the ship are too large. Especially when the docking Angle is large, the bow of the ship contacts the dock and the rubber fender before the middle of the hull, resulting in small impact kinetic energy concentrated on one or several fenders, resulting in damage to the rubber fender. The ship impact function is too large, in addition to the above reasons, there are more than the design ship type and tonnage of the ship dock berthing and wind waves on the ship's impact.

2. Poor anchoring and connection

This situation has occurred in all kinds of rubber fenders. Rubber fender loose, out of position, scattered into the sea and other abnormal scenes. The secondary reason for this scene is that the technical situation of the bolts or chains anchoring the fender is not good, or the maintenance is not kept up. The anchoring bolts, iron chains and other metal materials that fix the fender rust very fast in the land environment, and are not easy to change, resulting in poor fixing of the rubber fender, which seriously affects the normal use of the fender. Although the design of some anchoring bolts is considered to change the conditions, it is often not ideal in practical application. For example, V-type rubber fender anchorage bolts are tied to the way of embedded bolt boxes. The original design intention is to facilitate the maintenance and replacement of anchoring bolts, but in actual use, it can not be replaced due to iron rust, bolt deformation and other reasons, which affects the fixed quality of rubber fender, resulting in scattered and damaged fender.

3. Friction damage

This condition commonly occurs in the fixed V and D fender. The fender is mainly damaged by falling corners, cracking, external scratches and so on. The secondary cause of this damage is too much friction between the rubber fender and the ship. When the ship docks at a large tangential speed, the rubber fender and the hull contact part of the friction is too large and voluntarily moves forward with the ship, forming the fender is damaged by shear. In addition, during the period of mooring operations, the ship sometimes needs to move forward and backward, and the ship is composed of waves, currents, left and right or up and down. In this case, when the coefficient of friction between the ship and the rubber fender is greater than 0.4 (such as the cable is pulled too tight), there is damage that can constitute the fender.