Numerical study of the coupled motion responses in waves of side-by-side LNG floating systems

The paper presents a numerical and experimental study of multi-body systems composed of two floating structures floating side-by-side in head seas. This type of arrangement is being investigated for the operation of liquefied natural gas (LNG) transfer from a floating production platform to a shuttle tanker in an offshore environment. The floating structures are moored amongst themselves and floating in close proximity. The objective is to investigate the first order relative motions of side-by-side moored floating structures and the loads on the mooring lines and fenders, and to validate the existing numerical method by comparing to experimental results. Two case studies are analyzed. The first consists of two similar tankers moored together in intermediate water depth (80 m). The second configuration considers a floating production storage and offloading system for production of LNG (FLNG), with a side moored shuttle tanker. The experimental work was carried out in two offshore wave basins with scaled models subjected to irregular operational seastates. The measured responses include the motions of the two floating structures and the loads in the mooring lines connecting them. A Green's function panel method is used for the hydrodynamic calculations.