Abstract

Given industry concerns about the rising cost of performing deepwater installations, Lankhorst Ropes Offshore Division has developed a rope test machine that is expected to provide insights into deepwater mooring rope behaviour and optimise installation scenarios. For example, more accurate information on the degree of pre-loading required will avoid the high cost and safety issues surrounding excessive pre-loading during offshore installation.

Naval architects need comprehensive fibre rope test data when designing rope mooring systems. The rope test machine will provide the opportunity to conduct extensive testing of stiffness and degree of stretch under maximum load for a range of rope constructions, together with 'what if' scenarios by simulating storms and hurricanes, and loop current events with associated vortex induced vibrations on the mooring lines.

Using the rope test results, a new approach to pre-tensioning ropes ahead of installation is described. The approach is designed to address the issue of installing ropes of increasing stiffness and their associated higher mooring installation costs. In so doing it is intended to equip naval architects with a greater understanding of the performance of different synthetic yarns and rope constructions when designing deepwater mooring systems, and the role of pre-tensioning during installation.

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