The Design of Marine Fender System

Part 1. The Vessel

In most cases, the actual values of the ships are used to calculate the berthing energy. Under some circumstance, the actual values are not available, then the list “Standard Size of Vessels” can be referred for calculations.

Terminology of the vessel

Note: DPT=DWT+LW

Part 2. Berthing energy calculation

The berthing energy calculation is subject to the berthing method of the vessel which can be defined as following:

a. Side berthing, as shown in the figure 1 and 2
Then E= 1/2gMd. V2Cm • Ce • Cc • Cs

b. Passing in and out berthing, as shown in the figure 3
Then E= 1/2gMd. (Vsina)2Cm • Ce • Cc • Cs

c. Ship-to-Ship berthing, as shown in the figure 4
Then E= 0.5 [(Md1•Cm1) • (Md2•Cm1)/ (Md1•Cm1) + (Md2•Cm1)] • V2Cm • Ce

d. Stern berthing, as shown in the figure 5
Then E= 0.5MdV2

Where
E—Vessel effective berthing energy
Md—Displacement Tonnage (ton)
V—Berthing Velocity (m/s)
Cm—Added Mass Coefficient
Ce—Eccentricity Coefficient
Cs—Softness Coefficient, normally takes 1
Cc—Berth Configuration Coefficient, normally takes 1

1) Berthing Velocity V
In processing of fender system design, berthing velocity is a most important parameter. It depends on many factors such as Vessel size, load condition, port type etc. Therefore the berthing velocity is preferred to be obtained from actual measurements or relevant existing statistic information. When the actual measured speed velocity is not available, the BSI and PIANC standards shall be adopted to determine the required velocity value from the following chart.

a. easy berthing and sheltered
b. difficult berthing and sheltered
c. easy berthing, exposed
d. good berthing, exposed
e. difficult berthing, exposed

The berthing velocity can be calculated more precisely by using the following formulation while the ship DPT is 10000 ton-500000 ton.

Berthing Velocities Table

V1a1≈0.599 • Md-0.4423
V1b1≈8406 • Md-0.4031
V1c1≈10885 • Md-0.3899
V1d1≈12452 • Md-0.3748
V1e1≈12893 • Md-0.3625

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