AbstractsEngineering

One of the challenges of offshore loading and discharge are the relative horizontal motions between the HTV and its cargo which must be controlled, to ensure safe and reliable operations. Optimization of the cargo handling system is needed to control the relative horizontal motions. This study investigates whether the mooring device ShoreTension will minimize the relative horizontal motions between a HTV and a cargo, when it is used as the cargo handling system during offshore loading and discharge operations. A MATLAB function of ShoreTension is developed, which is implemented into AQWA to predict the relative horizontal motions between the HTV and the cargo in time. Multiple simulations have been performed, each with its own cargo handling system. A simplified MATLAB mass-spring-ShoreTension model resembling the HTV and the cargo is set up to determine why and when ShoreTension reduces motions. A cargo handling system including ShoreTension cannot reduce the high-, wave-frequent relative horizontal motions occurring between the HTV and the cargo, as they are induced by an excitation frequency far beyond the natural frequency of the original system. Furthermore, a cargo handling system including ShoreTension should be able to lower the low-frequent relative horizontal motions, which are the result of resonance; by increasing the stiffness and by adding damping through giving out and heaving in the mooring line. The optimal configuration has not yet been found. It is recommended to further investigate in how ShoreTension should be outfitted as cargo handling system such that the low-frequent relative horizontal motions are minimized.