As Large LNG Carrier has to trade in many LNG terminals, mooring system compatibility with terminals is one of key points in general layout of such vessels. Main compatibility items of mooring system is presented. Key factors of mooring system design are introduced, including mooring arrangement, mooring calculation, environment combination, design criteria, etc. Three typical mooring compatibility cases are analyzed: Case A based on mooring to terminal and standard OCIMF environment;Case B based on mooring to terminal, standard OCIMF environment and local environment required by terminal; Case C based on mooring to FSRU (ship-to-ship) and standard OCIMF environment. It can be seen that for certain terminal, the selected environment for mooring analysis shall be based on terminal requirement in additional to standard OCIMF environment. When wave shall be considered, wind speed of standard OCIMF environment has to be reduced in order to meet OCIMF 50%-line load limit. For ship-to-ship mooring, mooring lines for both mooring to terminal and ship-to-ship can follow OCIMF limits by lowering wind speed. These findings are helpful for mooring system compatibility of Large LNG Carrier.
As an important part of the LNG industry chain, LNG maritime transportation is highly valued for its safety by shipyards, shipowners, and ship management companies. Mooring as connection method between LNG vessels and terminals plays a crucial role in achieving safe transmission of LNG between vessels and shore stations and mooring is the key checking point of ship-shore compatibility (Li, Liang and Jiao et al., 2020). At present, certain mooring research for LNG carrier have been carried out only based on the pattern of mooring to terminal(Banfield and Flory, 2009; Hu, Hu and Liu et al., 2012; Zhou, Liang and Shi, 2017). However, the mooring pattern of large LNG carrier is complex. To date, relevant reference research on different mooring patterns of large LNG carrier in China is rarely reported.
In this paper, the main mooring compatibility items and characteristics of terminal mooring system design are introduced. In order to introduce the verification method of terminal mooring system, a 175000 m3 LNG carrier is taken as an example for calculation. Different mooring patterns are studied in order to find necessary mooring analysis cases. Comparative mooring analysis based on environment standard of OCIMF MEG4 (2018, hereinafter referred to as OCIMF) and local environment are also carried out. These findings are promising to provide a basis for issuing a guideline for the design and calculation of terminal mooring system of large LNG carrier.
