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3. ADVANTAGES

3.1 Safety and Reliability

Yokohama Pneumatic Rubber Fenders are constructed of several layers of strong tire-cord, and are thus resistant to pressure and cutting. The safety factor adopted in the design of this fender is based on accepted theory and has been proven by extensive experimentation. Operational experience over a long period of time attests to its high safety and reliability, and hydraulic pressure tests have proven the strength to be suitable. Furthermore, large-size fenders are equipped with a safety valve to release the inside air in the event of accidental over-pressure. The figure below shows data obtained from many destructive pressure tests at various percentage compressions. Such data are used to establish a basic minimum endurable pressure (MEP) curve for pneumatic rubber fenders.

3.2 No Deterioration or Variation in Performance

Yokohama Pneumatic Rubber Fenders utilize the compressive elasticity of air, therefore performance deterioration due to fatigue is absent.

In the case of solid rubber fenders or foam-filled fenders, based on data were taken from comparison tests of Yokohama Fenders, there are variations in performance. Such performance variations are associated to changes of rubber or foam hardness occurring as a result of cyclic compression and temperature change.

In the case of Yokohama Pneumatic Rubber Fenders, if the pressure is maintained properly, such variations are absent.

Yokohama Pneumatic Rubber Fenders also fully comply with the durability test required by ISO17357-1:2014. After 3000 repetitive cycles, there must be no cracks or other harmful defects on any part of the fender. Any reduction of the guaranteed energy absorption (GEA) is not accepted.

Reaction force at GEA (index) 1       1.04

Deflection at GEA (%)       60     60.4

The good performance of the Yokohama Pneumatic Rubber Fenders remains unchanged even at temperatures under -50 degrees Centigrade (-58 degrees Fahrenheit).

3.3 Advantages at Inclined Berthing

Ships usually make initial contact with the dock or another ship on STS operations at an oblique angle. In the case of solid rubber fenders or foam fenders, rated reaction force and energy absorption decreases considerably at inclined compressions compared with parallel compression. In order to compensate for the decrease of energy absorption at inclined compression, it is necessary to use larger sizes in the case of solid rubber fenders or foam fenders.

In the case of Yokohama Pneumatic Rubber Fenders, energy absorption does not decrease at inclined compression up to 15 degrees.

Distribution of load is also comparatively even because of the molecular freedom of air and high flexibility of the multi-layered cord-reinforced rubber membrane. This makes the body of a pneumatic rubber fender more shape conformant compared to solid or foam fenders, and thus able to better distribute the load along the hull of a ship or jetty structure during inclined compression.

3.4 Most Cost Competitive System

The utilization of the compressive elasticity of air, unlike other fenders which need protector panels, provides completely uniform surface pressure on contact, making Yokohama Pneumatic Rubber Fenders ideal. The surface pressure of the Yokohama Pneumatic Rubber Fenders is equal to the internal air pressure. The pressure of some is below 150kN/m2 (15 ton/m2). Due to low and uniform surface pressure properties, the Yokohama Pneumatic Rubber Fenders are popular at LNG-ship terminals.

3.5 Soft Reaction Force for Ship and Jetty Structure

Although all fenders should be used within their maximum load limit, it often happens that fenders accidentally receive excess load. The reaction force of Yokohama Pneumatic Rubber Fenders does not increase sharply, even under excess load conditions. Therefore, the Yokohama Pneumatic Rubber Fenders perform well in such cases, and protect ships and mooring facilities. In contrast, the reaction force of solid rubber fenders, including buckling-type fenders, increases sharply under excess load conditions.

The excess load turns the solid-type fender into a solid rubber block, which cannot perform as a fender. This often leads to damage of the ship and mooring facilities.

3.6 Lower Mooring Forces under Rough Weather Conditions

During mooring under rough weather conditions such as high waves and strong wind, large ship motions are induced by high waves, long period waves or a resonant effect between the natural period of a ship and the predominant period of the waves.

This movement results in compression and shearing forces on fenders. The reaction force and deflection of solid-type fenders under rough weather conditions easily reaches their respective maximums. Therefore, repeated compression with shearing force resulting from the movement of ships causes fatigue and often damages solid-type fenders. On the other hand, the reaction force and deflection of Yokohama Pneumatic Rubber Fenders do not easily reach the maximum because the reaction force increases slowly and allowable deflection is wide. Thus, the Yokohama Pneumatic Rubber Fenders safely protect ships and mooring facilities even under rough weather conditions.

The use of Pneumatic Rubber Fenders sometimes eliminates the necessity of constructing a breakwater in the harbor. There are many studies and reports relating to the above subjects.

3.7 Stronger against Shearing Force

After contacting a dock, a ship is usually shifted to the correct mooring position. The shifting exerts shearing and compression forces on the fenders. This combined force is very severe in the case of solid rubber fenders because they are not reinforced against such force. In contrast, Yokohama Pneumatic Rubber Fenders are adequately reinforced using strong tire-cord to cope against such forces as well as internal pressure.

3.8 Adaptable to the Tide

Yokohama Pneumatic Rubber Fenders basically float on the water in an unrestricted vertical plane corresponding to the tidal range and ship's vertical movement.

This means that energy absorption always takes place at the most suitable position, and that only one fender is required per dolphin.

3.9 Simple and Low Cost Installation

The weight of Yokohama Pneumatic Rubber Fenders is supported by the water on which it floats. Therefore, the fender can be moored simply by means of a guy rope or chain, requiring minimal extra cost. It can be removed easily to a suitable jetty or quay when not in use, or transferred to another mooring point whenever required.

3.10 Low Maintenance Cost

Maintenance cost is very low. Although the internal pressure will vary with seasonal changes, the air leakage is so minimal that it is sufficient to check the air pressure only once a year. The chain net needs to be replaced only once in 3 or 4 years, depending on ambient conditions.

3.11 Shipping Cost Minimization

In order to minimize the shipping cost of Yokohama Pneumatic Rubber Fenders, the fenders are usually packed and shipped in containers or on pallets in vacuumed and folded down state.