Experimental Study of the Effect of Waves on SPAR Responses with and without Heave Plate in Intact and Damaged Mooring Systems

Abstract

: This research discusses the effects of heave plate utilization against dynamic responses of SPAR due to random waves. The analysis has been done by numerical and experimental methods. The experimental method was held in Maneuvering Ocean Engineering Basin of Balai Teknologi Hidrodinamika (BTH) – BPPT. The model scale of SPAR was constructed based on the classic SPAR prototype with taut mooring systems using four identical moorings in a 1:125 scale factor. Both experimental and numerical studies were conducted in time domain analysis with heave plate utilization in the keel of SPAR as the main variable. The diameter of the heave plate has a 1.5 ratio to the outer diameter of SPAR. Each analysis was conducted in intact and damaged mooring systems. The analyzed variables of dynamic responses are the surge, heave, pitch, and maximum offset of the SPAR. Results of both the experimental and numerical studies were then be compared, showing that the heave plate does not affect surge and pitch responses significantly. On the other hand, it significantly and consistently reduces the SPAR heave responses in every condition of analysis in both the numerical and experimental methods. The most significant reduction of SPAR heave response occurred when the mooring systems were in damaged condition, i.e., 33.29% and 27.84% heave reduction in the experimental and numerical method, respectively. The study also shows that the heave plate reduces SPAR maximum offset up to 31.69% in experimental analysis and 11.22% in numerical analysis.