Experimental Investigation of Mooring Line Loading Using Large and Small-Scale Models

Abstract

For catenary mooring lines, the relationship between excursion of the point of suspension and the length of suspended line is highly nonlinear. If the point of suspension is then set in motion, the velocity of the line resulting from a change in catenary profile induces additional nonlinear hydrodynamic loading components. The sensitivity of the mooring line to initial and oscillatory conditions results in a complicated tension history at the point of suspension, with line tensions possibly greatly exceeding those predicted by static analyses. This paper presents results from an experimental investigation into the response of a large (1:16) and small (1:70) scale single-chain catenary model mooring line when subject to a comprehensive, and equivalent, range of excitation parameters. Tests were performed at purpose-built test facilities. Small-scale model tests were carried out at University College London (UCL). Large-scale model mooring line tests were completed at the Ship Dynamics Laboratory, Canal de Experiencias Hidrodinamicas de El Pardo (CEHIPAR), Madrid, Spain. Funding for the model tests performed in Spain was provided through the European Union Access to Large Scale Facilities—Training and Mobilisation of Researchers Program.