Optimum Waterline Geometry for Deepwater Platforms

The dynamic behavior of deepwater platforms can be improved by maximizing wave force cancellation at their natural frequencies of interest. This can be achieved by optimizing both the platform waterline geometry, and the structural dynamic characteristics. This study outlines a simplified procedure by which different water-line geometries for deepwater structures can be evaluated. This procedure considers effect of wave directionality. Comparison between different waterline geometries is performed. Results are presented for four, six, eight, sixteen-column, or leg, configurations, as well as for columns (or legs) located in Triangle, Pentagon, and Hexagon configurations. For each configuration, reduction in the external loading as a function of frequency is quantified. Procedures and results presented in this paper can be easily used in selecting optimum platform waterline geometry, leg spacings, and conductor locations in early design stages.