Risk analysis for green water of single-point moored ship

Abstract

ObjectiveThe purpose of this paper is to predict the green water risks of a single-point moored ship.MethodsTherefore, a combined method of coupled dynamic analysis and air gap analysis is proposed. The air gap analysis points are chosen on the deck and bulwark of the ship，where the air gaps of these points under different sea states are calculated using dynamic analysis in the time domain. It is found that the bow and poop deck are the position where green water occurs most on the single point moored ship. Based on the extreme value theory and Monte Carlo method respectively, the failure probability of green water at several key analysis points are calculated. ResultsAmong all points, the maximum probability of green water is 1.46×10−4 based on the extreme value theory, while the result of the Monte Carlo method is 9.93×10−7.ConclusionsIn comparison with the failure probability of green water calculated via the Monte Carlo method, the value calculated via the extreme value theory is higher. When the sample space is not large enough, the extreme value theory can conservatively predict the risk of green water.

Keywords

• single-point moored ship
• green water
• air gap
• extreme value theory
• monte carlo method