Vessel Drift-Off |
 
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Vessel Drift-Off |
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Simulation of vessel drift-off is achieved via the inclusion of an explicitly modelled moored vessel in the analysis. The objective is to compute the drift motion of the vessel due to current, wind, and second order drift forces computed from a wave spectrum. The vessel itself is modelled as an assemblage of rigid mass-less beam elements, with a node located at the vessel CoG. These “vessel” elements connect the vessel CoG to those riser nodes whose motions are defined by the motions of the vessel. The wind loads are computed using the wind velocity, air density, wind coefficients and the moored vessel dimensions.
The current loads are computed by a combination of the current velocity, seawater density, current coefficients and the moored vessel dimensions. The wave drift loads are calculated from user-specified Quadratic Transfer Functions (QTFs) and the discretised wave spectrum.
