Effects of Anchor Chain Arrangements on the Motion Response of Three-Anchor Buoy Systems

As a new kind of large observation platform, the three-anchor buoy system can effectively realize multifunctional ocean observation, e.g., ocean profiling and autonomous underwater vehicle docking. In order to understand effects of different anchor chain arrangements on the motion response of the three-anchor buoy system under the coupling effect of wind, wave, and current loads, a hydrodynamic model of the buoy system was developed. Wave-period-dependent characteristics of added mass, radiation damping, and the motion response amplitude operator (RAO) were analyzed to derive their response curves; the effects of adding additional viscous damping on RAO performance were investigated. Subsequently, frequency domain and time domain analyses were conducted on five three-anchor buoy systems with distinct anchor chain arrangements to investigate the variation patterns of 6-DOF motion response amplitudes, top-chain tension characteristics, and submarine anchor chain length alterations under combined wind, wave, and current loading conditions. The results show that under the same environmental load, when the three anchor chains are evenly distributed at 120°, the 6-DOF motion response amplitude of the buoy system is the smallest, the top-chain tension and the submarine anchor chain length are more in line with the design requirements, and the comprehensive performance is better.