28 July 2005
All fender systems selected should be capable of safely transferring the
environmental loads on the ship to the mooring structure.
Design all fender systems to prevent permanent deformation of the ship's hull. It
is much more expensive to repair a ship's hull than rehabilitate a damaged fender
system. The composition of a typical Navy hull is steel plating welded to
longitudinal (horizontal) stiffeners at 2 to 4 ft (0.6 to 1.2 m) on center. The
stiffeners span from 5 to 20 ft (1.5 to 7.6 m) depending on the vessel. Generally,
the stiffeners are of sufficient strength to preclude failure from fender loading.
However, the hull plating may yield when subjected to a uniformly distributed
overload on the panel. Fender systems with rigid face elements or in
combination with rigid camels tend to concentrate the reaction forces on the
ships frames versus the hull plating due to the relative stiffness of the frames.
BERTHING ENERGY DETERMINATION.
The following methods can be used in the determination of berthing energy of the
The kinetic energy method has been the widely accepted method for piers and
wharves of Naval facilities. When the displacement tonnage of the ship is
known, the energy equation can be written as:
Eship = Wv2/g
Eship = Berthing energy of ship (ft-lbs)
= Weight of the ship in pounds (displacement tonnage x 2,240)
= Berthing velocity normal to the berth (ft/second)
However, there are several factors that modify the actual energy to be absorbed
by the fender system. The expression can be written as