3 Common Causes of Rubber Fender Damage & How to Prevent Them

1. Ship overloaded

This kind of damage often occurs in rubber fenders, especially some old rubber fenders, which often crack at the weak points of the structure. The cracks are generally along the length of the rubber fender. D-type and V-type fenders are more common. The main reason for the cracking of the rubber fender is that the kinetic energy of the ship hitting the fender is too large, which exceeds the load that the rubber fender can withstand. The reason for the excessive kinetic energy of the ship's impact is the excessive speed and angle of the ship. Especially when the berthing angle is large, the bow of the ship contacts the pier and the rubber fender before the middle of the hull, causing strong impact kinetic energy to concentrate on one or several fenders, causing damage to the rubber fender. In addition to the above reasons, the ship's impact function is too large. There are also ships that are berthed at the docks larger than the designed ship type and tonnage, and the impact of wind and waves on the ship.

2. Poor anchorage and connection

This situation has occurred in all types of rubber fenders. The rubber fender is loose, out of position, falling off into the sea and other abnormal phenomena. The main reason for this phenomenon is that the bolts or iron chains that anchor the fender are in poor technical condition, or the maintenance has not kept up. Metal materials such as anchor bolts and iron chains for fixing the fender corrode very quickly in the marine environment and are not easy to replace, resulting in poor fixing of the rubber fender, which seriously affects the normal use of the fender. Although some anchor bolts are designed to consider replacement conditions, they are often not ideal in actual use. For example, V-shaped rubber fender anchor bolts are in the form of embedded bolt boxes. The original design intent was to facilitate the repair and replacement of anchor bolts, but in actual use, it cannot be replaced due to iron corrosion, bolt deformation and other reasons, which affects the quality of the rubber fender fixing, causing the fender to fall off and damage.

3. Friction damage

This situation generally occurs in fixed V-type and D-type rubber fenders. Fenders are mainly damaged by corners, cracks, and surface scratches. The main reason for this damage is that the friction between the rubber fender and the ship is too large. When the ship arrives at a higher tangential speed, the contact part of the rubber fender and the hull is forced to move forward with the ship due to excessive friction, causing the fender to be sheared and damaged. In addition, during the mooring operation, the ship sometimes needs to move forward and backward, and the ship shakes left and right or up and down caused by waves and currents. In this case, when the coefficient of friction between the ship and the rubber fender is larger than 0.4 (for example, the mooring rope is too tight), it may cause damage to the fender.

Summary: Common Rubber Fender Damages & Professional Solutions

To ensure long-term dock safety, understanding the relationship between damage types and their root causes is essential. Below is a quick reference guide:

Frequently Asked Questions: Rubber Fender Damage & Maintenance

Why is my V-type rubber fender cracking along its length?

Longitudinal cracking in V-type rubber fenders is typically caused by over-compression during berthing. When a vessel strikes the fender at an excessive angle or high speed, the concentrated kinetic energy exceeds the rubber's structural design limit. This intense localized pressure forces the rubber to split along its weakest points, usually resulting in cracks that run parallel to the fender's length.

How often should marine rubber fenders be inspected for damage?

We recommend a comprehensive professional inspection every 6 to 12 months. Your maintenance team should focus on four critical areas:

• Anchor Bolt Tension: Ensure no bolts have loosened due to vibration.

• Chain Integrity: Check for corrosion or wear in the tension and weight chains.

• Rubber Fatigue: Look for surface "crazing" or deep structural cracks.

• UV & Chemical Degradation: Check if the rubber has become brittle due to prolonged sun exposure or oil contact.

Can a damaged rubber fender still protect the dock?

Once a fender shows structural cracks or loses its mounting stability, its energy absorption capacity is significantly compromised. Using a damaged fender increases the risk of "bottoming out," where the impact force is transferred directly to the dock wall, potentially leading to catastrophic structural failure of the pier.

Does the fender's color or surface finish indicate damage?

Not necessarily. While some surface fading is normal due to UV exposure, deep chalking or hardening indicates that the rubber's antioxidant properties are failing. If the surface becomes brittle, it is much more susceptible to friction damage and tearing.