The kinetic berthing energy demand shall be determined in accordance with Section 3103F.6.
For existing MOTs, the berthing energy capacity shall be calculated as the area under the force-deflection curve for the combined structure and fender system as indicated in Figure 31F-5-5. Fender piles may be included in the lateral analysis to establish the total force-deflection curve for the berthing system. Load-deflection curves for other fender types shall be obtained from manufacturer's data. The condition of fenders shall be taken into account when performing the analysis.
When batter piles are present, the fender system typically absorbs most of the berthing energy. This can be established by comparing the force-deflection curves for the fender system and batter piles. In this case only the fender system energy absorption shall be considered.
A continuous fender system consists of fender piles, chocks, wales, and rubber or spring fender units.
The contact length of a ship during berthing depends on the spacing of the fender piles and fender units, and the connection details of the chocks and wales to the fender piles.
The contact length, Lc, can be calculated using rational analysis considering curvature of the bow and berthing angle.
In lieu of detailed analysis to determine the contact length, Table 31F-5-1 may be used. The contact length for a vessel within the range listed in the table can be obtained by interpolation.
|VESSEL SIZE (DWT)||CONTACT LENGTH|
|1,000 to 2,500||35 ft|
|5,000 to 26,000||40 ft|
|35,000 to 50,000||50 ft|
|100,000 to 125,000||70 ft|
For discrete fender systems (i.e., not continuous), one fender unit or breasting dolphin shall be able to absorb the entire berthing energy.
The longitudinal and vertical components of the horizontal berthing force shall be calculated using appropriate coefficients of friction between the vessel and the fender. In lieu of as-built data, the values in Table 31F-5-2 may be used for typical fender/vessel materials:
|CONTACT MA TERIALS||FRICTION COEFFICIENT|
|Timber to Steel||0.4 to 0.6|
|Urethane to Steel||0.4 to 0.6|
|Steel to Steel||0.25|
|Rubber to Steel||0.6 to 0.7|
|UHMW* to Steel||0.1 to 0.2|
F = longitudinal or vertical component of horizontal berthing force
µ = coefficient of friction of contact materials
N = maximum horizontal berthing force (normal to fender)
For guidelines on new fender designs, refer to UFC 4-152-01 [5.8] and PIANC [5.9]. Velocity and temperature factors, contact angle effects and manufacturing tolerances shall be considered (see Appendices A and B of PIANC [5.9]). Also, see Section 3103F.6.