UFC 4-159-03
3 October 2005
These cases show that the type of behavior of a given ship at a given
single point mooring in a given environment can be very complex (Wichers, 1988), even
though the wind and current are steady. It is recommended that a dynamic stability
analysis first be conducted (Wichers, 1988) at the early stages of single point mooring
design. Then the type of analysis required can be determined. The results from this
analysis will suggest what type of method should be used to design a single point
mooring. These methods are complex and beyond the scope of this UFC. Behavior of
single point moorings is illustrated by example.
8-2.1
Background for Example. In this example two moorings were designed
and installed. The original designs were based on quasi-static methods. Ships moored
to these buoys broke their mooring hawsers when a wind gust front struck the ships. In
this example, the design and hawser failures are reviewed. The effects of wind
dynamics on a single point mooring are illustrated.
Ship. A single 2nd LT JOHN P. BOBO (T-AK 3008) class ship was
8-2.2
moored at each of two fleet mooring buoys. Table 8-1 gives basic characteristics of the
ship.
Table 8-1. 2nd LT JOHN P BOBO Parameters (Fully Loaded)
PARAMETER
DESIGN BASIS
DESIGN BASIS
(SI units)
(English units)
Length
633.76 ft
193.2 m
Overall
614.58 ft
187.3 m
At Waterline
614.58 ft
187.3 m
Between Perpendiculars
Beam @ Waterline
9.80
32.15 ft
Draft
9.75 m
32 ft
Displacement
4.69E7 kg
46111 long tons
Line Size (2 nylon hawsers)
-
12 inches
152
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