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Mooring of the terminal
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A number of possible concepts for mooring the terminal has been identified. The task now is to determine which concept is most suited for the floating container terminal. To determine this, a multicriteria analysis (MCA) has been carried out. In this analysis the concepts have been evaluated using a set of criteria. As can be seen in the MCA, the concepts with the internal turret and the single buoy mooring have not been evaluated. Since the floating terminal will have a bridge connection to shore, it is not allowed to change heading (or weathervane). The internal turret and single buoy concepts are both used for weathervaning constructions and are therefore not suited for mooring the terminal.
The concepts have been compared using a number of criteria. Since not every criterium is equally important in the final decision, weighing factors have been assigned to every criterium. This finally leads to an overall score of the concept. The dolphin concept turns out te be most favourable for mooring the floating container terminal.
(click on the criteria in the legenda for further explanation)
There are four types of dolphins, each with its own advantages and disadvantages. In previous studies, the four types have been compared on four different criteria. The four types and their scores on aspects as reliability, construction, maintenance and usage are mentioned here.
The forces acting on the floating terminal are transferred to the mooring dolphins by fenders. The maximum fender reaction is 2300 kN. The number of fenders needed to support the FCT can now be calculated from the environmental conditions and forces. The maximum force acting on the FCT in transverse direction is 15,500 kN indicating a minimal number of 7 fenders. For redundancy a safety factor of 1.4 is applied. Thus 10 fenders are needed in transverse direction. The maximum force acting on the FCT in longitudinal direction is 6000 kN, demanding 4 fenders when including the safety factor.
Ship mooring alongside As mentioned, the terminal will have to withstand a "rough" mooring of a containership. The model described in the Terminal -> Forces section results in a speed of both terminal and vessel of 0.21 m/s. The kinetic energy of these masses will have to be absorbed by the dolphin's fenders. The fenders installed on the dolphin are assumed to be one of the largest available, with a diameter of 2 meters. With a design deflection of the fenders of 50%, this results in a design deflection of 1 meter. Within this distance, the fenders will have to absorb the total kinetic energy of both the terminal and the moored vessel. A simple energy conservation calculation results in a required stiffness of the fenders of 1585 kN/m. The total force on the dolphins in this worst case scenario turns out to be 15,850 kN; approximately the same force acting on the terminal during a typhoon. Thus the maximum force on the fenders is marginally higher than the before assumed 15,500 kN. But it must be stated that the method used does not take into account the row of fenders between ship and terminal. Furthermore, a safety factor is included in the fender reaction forces and in the dolphin strenght. Therefore, there is no need to adjust the number of fenders determined before.
A cross section of the floating terminal at a dolphin location is shown below
The pictures below show a topview and a side view of the terminal's mooring dolphins arrangement
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