Effect of Mooring Lines Pattern in a Semi-submersible Platform at Surge and Sway Movements

Hadi Sabziyan¹, Hassan Ghassemi^2, , Farhood Azarsina¹ and Saeid Kazemi³

¹Department of Marine Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, Iran

²Department of Ocean Engineering, Amirkabir University of Technology, Tehran, Iran

³Department of Ocean Engineering, Khalij-e Fars University, Bushehr, Iran

Cite this paper:
Hadi Sabziyan, Hassan Ghassemi, Farhood Azarsina and Saeid Kazemi. Effect of Mooring Lines Pattern in a Semi-submersible Platform at Surge and Sway Movements. Journal of Ocean Research. 2014; 2(1):17-22. doi: 10.12691/jor-2-1-4

Abstract

Exposure to environmental conditions at sea for floating structures is inevitable. Environmental conditions that waves are most important of them will enter forces on structure of semi-submersible platforms. Therefore such structures should be deployed in the operational capability of their own, that one of these methods is mooring them. In this condition, structure shows different behavior compared with unmoored structure. Wave force cause motions of structure and subsequently produce tension force on mooring lines. Hence, investigation of structure movements and selection an appropriate mooring system to minimizing the structure motions must have been discussed. semi-submersible platforms mooring systems results restoring force in horizontal plane, and thus control degree of freedom on Surge, Sway and Yaw movements. This study estimated Surge and Sway movements of a semi-submersible platform when that it has been exposed to 0, 45 and 90 degrees of sea wave direction with the environmental conditions of the Caspian Sea using Flow-3d (version10.0.1) software. Also the seven symmetric mooring systems in the form of 4 and 8 numbers of mooring lines’ systems have been used to investigate the best modes.

Keywords:
semi-submersible platform mooring lines Surge Sway

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