Efender = Cb x Cm x Eship

where:

Efender = Energy to be absorbed by the fender system

Cb

= Berthing coefficient = Ce x Cg x Cd x Cc. Sometimes Eccentricity (Ce),

geometric (Cg), deformation (Cd), and configuration (Cc) coefficients are

combined into a single value called berthing coefficient.

Cm

= Effective mass or virtual mass coefficient

Each of these coefficients is discussed separately below.

c. Eccentricity Coefficient (Ce). During the berthing maneuver, when the

ship is not exactly parallel to the berthing line, not all the kinetic energy of

the ship will be transmitted to the fenders. Due to the reaction from the

fender, the ship will start to rotate around the contact point, thus

dissipating part of its energy. Treating the ship as a rigid rod of negligible

width in the analysis of the energy of impact on the fenders leads to the

simple formula:

Ce = k2/(a2 + k2)

where

k = Radius of longitudinal gyration of the ship, ft.

a = Distance between the ship's center of gravity and the point of contact on the

ship's side, projected onto the ship's longitudinal axis, ft.

Values of Ce typically are between 0.4 and 0.7. The values for Ce may be

computed from Figure 5-2.

d. Geometric Coefficient (Cg). The geometric coefficient, Cg, depends

upon the geometric configuration of the ship at the point of impact. It

varies from 0.85 for an increasing convex curvature to 1.25 for concave

curvature. Generally, 0.95 is ended for the impact point at or beyond the

quarter points of the ship, and 1.0 for broadside berthing in which contact

is made along the straight side.

e. Deformation Coefficient (Cd). This accounts for the energy reduction

effects due to local deformation of the ship's hull and deflection of the

whole ship along its longitudinal axis. The energy absorbed by the ship

depends on the relative stiffness of the ship and the obstruction. The

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