Floatover is a new method for installing integrated topside onto a spar, which has several substantial advantages compared with using derrick barge. During some operation, the transport barge is moored in close proximity between two floatover barges. The relative motions between these three barges are concerned by designers and operators. The hydrodynamics of three side-by-side barges is more complex than for a single barge in waves. In this paper, numerical analyses in frequency domain were carried out for both multiple bodies system and single body. The numerical analysis tool was potential flow code WAMIT, using both low-order and higher-order boundary element method. Four different low order boundary element discrete and two different higher order boundary element discrete were adopted. Corresponding model tests were also performed in the Deepwater Offshore Basin in Shanghai Jiao Tong University. Comparison between numerical and experimental results shows that the response amplitude operators agree quite well and the effect of viscous damping is significant in roll mode. The results between multiple bodies system and single body show that the hydrodynamic interactions between barges are remarkable and motion responses are larger than single barge at some frequencies.


Currently, topside installation of offshore platform in open waters is always a great challenge for offshore operation, particularly for floating platform like spar. In this method, it transfers the topside of an offshore oil platform from transport barges onto the support structure directly through barge ballasting or floating substructure de-ballasting. Until now, there is only one successful floatover deck operation for spar platform. In 2006, the first floatover deck was installed on a spar named Kikeh in 1320m water depths in the South China Sea, which is described by Edelson (2008). The deck load was transferred from two floatover barges to spar hull.

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