Other recommendations pertinent to fender type selection
Selection of a fender system for given installation is based on the following factors. Pertinent recommendations are given as follows:
- Exposure conditions.In exposed locations or in areas subject to seiche, a resilient system such as a rubber fender system should be used. In sheltered basins, a standard timber-pile system, a hung system, or a retractable system is generally used.
- Berthing ship versus moored ship
- For locations where berthing operations are hazardous, stiff fender systems with high energy-absorption characteristics are advisable.
- For locations where the behavior of the already moored ship is the governing factor, soft fenders with soft mooring ropes are feasible in minimizing mooring forces and ship motion.
- Where berthing operations and the behavior of moored ships seem to pose problems of equal importance, it is best to choose a fender of intermediate type that can act stiffly during berthing and softly when the ship is moored Hydraulic-pneumatic fender systems meet such requirements.
- Acceptable lateral load to docks at berths for vessels up to 20,000 long-ton displacements, the acceptable lateral loading to dock should be kept within 3,000 to 3,500 pounds per linear foot of berth. Special tanker berth may be acceptable for higher lateral loading.
- Acceptable hull loads. For vessels from 15,000 to 20,000 tons, hull pressure of 35 psi is acceptable in general, with overloads of up to 50 psi as an upper limit.
- Maximum allowable distance between moored ships and dock face. The maximum limit is 4 to 5 feet for general cargo berth. No problem exists if the fender system is for a tanker berth involving fuel supply only.
- Pier type as related to fender system selection.
- Open pier. Any type of fender system may be applicable.
- Solid pier. This type has little resilience. Consider use of resilient or retractable fenders to minimize vessel damage.
- Miscellaneous factors related to fender system selection
- Resistance to tangential forces.
- Reliability in operation.
- Cost of maintenance.
- Evaluation of systems that have given satisfactory service at or near the proposed installation.
