Parametric optimization of a semi-submersible platform with heave plates

The hydrodynamic responses of a semi-submersible platform are driven by its mass properties and geometric parameters, e.g. column size, spacing, draft and pontoon size. The mooring system also influences the platform responses. Heave plates added to the base of each column have been proposed to enhanced stability of semi-submersible platforms, particularly in the lower payload range. Optimization of a platform typically involves a compromise among a large number of factors including the structural weight, vertical, horizontal motion and rotations in operating and extreme sea-states, airgap, mooring size, etc. Optimization methods are reviewed. The complexity of the problem leads to the choice of a genetic algorithm presented herein. To allow systematic platform optimization assuming primary project parameters are given, i.e. payload, waterdepth, environmental conditions. A simplified hydrodynamic model is developed to capture the parametric sensitivity of the platform responses to primary design parameters.