Dynamic response of three different floating platform (OC4, BSS, GVA) using multi-segment mooring system

Abstract

The design of mooring lines for floating platforms is an essential task to guarantee structure survivability and its components under different metocean conditions. This paper focuses on the application and comparison of the MSM-BMW system across various types of semisubmersible platforms, including the OC4-DeepCwind, the braceless semi-submersible (BSS) with three catenary mooring lines, and the drilling rig GVA 4000 with eight mooring lines. The performance of the BMW mooring system for these three platforms is compared under operational and survival conditions. The hybrid mooring concept is a multi-segment mooring (MSM) arrangement of the catenary and taut, including single buoy and multi-clump weight (BMW), generally named MSM-BMW. Hydrodynamic responses and mooring forces are compared between original and hybrid systems under regular and irregular wave conditions. The dynamic response of the platform is performed utilizing both Morrison theory and three-dimensional radiation/diffraction theory based on the boundary element method (BEM) in ANSYS-AQWA software. The results show that using BMW on the three floating platforms significantly reduces platform motion at low frequencies, with minimal effect on wave-frequency resonance. However, the BMW system increases mooring force at wave frequency, while having a smaller effect at low frequencies. The effectiveness of the BMW system varies across platforms and motion types. The BSS platform shows significant improvement in surge motion, while the GVA platform has the smallest ratio in heave motion. Additionally, the BSS platform demonstrates the least response in pitch motion.