Experimental Studies on a Scaled Model of a Tension Based Tension Leg Platform under Combined Mooring and Tether Conditions

Tension Based Tension Leg Platform (TBTLP) is an innovative concept wherein a Tension Leg Platform (TLP) designed for a certain depth can be extended to operate in deeper waters by mounting the surface structure (TLP) on a buoyant closed box structure, Tension Base. The motion control of Tension Base is very important for satisfactory performance of the mounted TLP. In this paper, the concepts are briefly introduced and experiments conducted on a 1:150 scaled model of the TBTLP in 3 m water depth with three different combinations of tether and mooring stiffnesses are presented. Experiments were also conducted on the same TLP (without Tension Base) in two different water depths (3 m and 1 m). Results are presented in terms of Response Amplitude Operators (RAOs) in the surge, heave and pitch degrees of freedom of TBTLP and are compared with RAOs of TLPs in 3 m and 1 m to highlight the efficacy of the new concept.