MOORING SYSTEM-DESIGN BASED ON ANALYTICAL EXPRESSIONS OF CATASTROPHESOF SLOW-MOTION DYNAMICS

Analytical expressions of the necessary and sufficient conditions for stability of mooring systems representing bifurcation boundaries, and expressions defining the morphogeneses occurring across boundaries are presented. These expressions provide means for evaluating the stabili ty of a mooring system around an equilibrium position and constructing catastrophe sets in any parametric design space. These expressions al low the designer to select appropriate values far the mooring paramete rs without resorting to trial and error. A number of realistic applica tions are provided for barge and tanker mooting systems which exhibit qualitatively different nonlinear dynamics. The mathematical model con sists of the nonlinear, third-order maneuvering equations of the horiz ontal plane slow-motion dynamics of a vessel moored to arte or more te rminals, Mooring lines are modeled by synthetic nylon rapes, chains, o r steel cables, External excitation consists of time-independent curre nt, wind and mean wave drift forces. The analytical expressions presen ted in this paper apply to nylon ropes and current excitation. Express ions for other combinations of lilies and excitation can be derived.