Study On Nonlinear Roll Motion And Sailing Safety Of Wing-assisted Ships

The use of clean energy (wind, solar, etc.) as propulsion to drive ship forward has a positive significance for ship’s energy conservation and emissions reduction. Among them, the wing-assisted technology which uses wind energy as the auxiliary propulsion to push the ship forward so as to achieve the energy saving and emission reduction is increasingly valued by people, and the applied research is developed on some ships. Because the wing-assistant technology is to get wing propulsion by using crosswind, the wing assist is affected by cross wind which causes the ship’s fixed angles. The ship rolling motion caused by wing-assist technology has some features different from other ship rolling. Therefore the study of the wing-assisted ships’rolling motion has a positive significance for safe sailing.The main purpose of this paper is to analyze the wing-assisted ships’rolling motion, forecast the rolling trend and quantitative forecast the wing-assisted ships’ capsizing probability in the condition of heavy and light seagoing based on the wave data of a typical Pacific region.This paper studies on the nonlinear dynamics of wing-assisted ships’rolling motion under random waves and formulated equations of wing-assisted ships’rolling motion based on the nonlinear stochastic dynamics theory and method; forecasts the rolling trend based on numerical analysis methods; and quantitative forecasts the wing-assisted ships’capsizing probability based on the wave data of a typical Pacific region quantitative. The main conclusions are as follows:(1) In the random waves, the wing-assisted ship will generate obvious fixed roll angles due to the resistance caused by the cross wind. So the influences of barycenter’s shift of bulk cargo on the security of bulk freighter should be considered if the ship using wing-assist technology for a long time.(2) The capsizing probability is much higher when the wing-assist ship sailing with light load than heavy load, so the wing-assisted technology’s effects on ship stability should be paid attention to.(3) The wing-assist ship should try to avoid light seagoing, or decrease wings to enhance stability.