Dynamic analysis of taut mooring systems

• Main Author: Lim, Wan Yu.
• Other Authors: Low Ying Min
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Civil engineering; DRNTU::Engineering::Civil engineering::Structures and design
• Online Access: http://hdl.handle.net/10356/52887
• Institution: Nanyang Technological University

This report is part of an ongoing study by two final year students (Rachel Amanda Netto and the author). The aim of the study is to investigate the effects of various design parameters on the dynamic response of taut mooring system using the simulation program OrcaFlex. Taut mooring system is increasingly applied in offshore deepwater oil drilling platform. Yet, the polyester rope taut leg mooring is a fairly new system that has been developed, hence warranting further study in the area. As the wide review of literature does not have certain important studies such as effect of water depth and influence of random variables on the mooring line. Parametric studies are carried out here to investigate the effects of 8-strand multiplait polyester rope taut mooring on the tension of the mooring lines and the motion of the platform using a time-domain coupling analysis. The parametric studies are made up of investigating the effects of direction of environmental loadings, the mooring lines arrangement, the number of mooring lines, the hydrodynamic coefficients CA and CD of mooring lines and the type of wave spectrum on the motion performance of the FPSO. In water depth of 800 meters, which is subjected to 100 year return wave height of 15.24 meters, a period of 14 seconds, current speed of 1.080 meters per second and a wind speed of 41.44 meters per second. The environmental loads here are acting in the same direction to investigate the maximum loads on the taut mooring lines. The experimental results show that the change in arrangement angles and the number of mooring lines have more significant impact on the mooring line tension and platform motion as compared to other parameters. Thus to have a more effective and cost efficient system, different simulations should be ran to have an improved and more realistic model of the mooring system that is going to be used.