The focus of the hydrodynamic research has been on deep water applications during the last decade. Recent experience with mooring in close proximity with another object has shown that interaction effects play a significant role in the prediction of the motions and mooring loads.
In typical close proximity situations such as side-by-side mooring and Gravity Based Structure mooring, strong interaction effects can be noticed not only for the wave forces, added mass and damping, but also on the drift forces. Further the viscous damping of the motions of the vessel in close proximity of another structure and moored in shallow water is a complex issue. Finally there is a significant interaction effect in the wind and current forces.
In this (experimental) paper the effect of the waterdepth and the distance between LNG carrier and GBS in calm water is studied. Modeltest data for two waterdepths (15 and 25 meter) and 3 distances between the LNG carrier and the GBS are analysed.
Finally the application of these results in a numerical time domain simulation model is discussed.
Results presented in this paper show that the damping is sensitive to the actual waterdepth and the actual distance between LNG carrier and the GBS.
Complex hydrodynamic effects play a role not only in the wave forces, added mass and damping, but also to the viscous damping. The small distance between the sides of the structures results in large velocities of the flow around the bilges. The same applies between the bottom of the moored vessel and the seabed in shallow water. This results in viscous damping effects too. Finally there is a significant interaction effect in the wind and current forces.