Design of Oceanographic Surface Moorings for Harsh-Weather Environments

摘要

A comprehensive methodology is presented for designing instrumented oceanographicsurface moorings for harsh weather environments. In the past, the design of oceanographic moorings was based on static analysis as most systems were deployed in regions where wave forcing was small. But now, many surface moorings are being placed in ocean environments where the predominant forcing is from waves and where the major cause of failure is cyclic fatigue. Here, dynamic analysis becomes as important as the static calculations. In this paper, we present the equations and numerical solution techniques for the statics and dynamics of a buoy/cable system with attached instruments. Hydrodynamic coefficients and wave exciting forces of different shaped oceanographic buoys are given along with the material parameters for the components and instruments that make up the mooring line. We show how to combine the results of the static and dynamic analysis with data from laboratory strength and fatigue tests of mooring components to predict if the mooring will survive the deployment. We present an analytical model of the dynamics of the mooring system that gives almost identical results with the numerical simulation and can be used during preliminary design. A comprehensive design example using the 1995 Arabian Sea surface mooring is presented to illustrate the design procedure.