Research On Vulnerability Criteria Of Parametric Rolling And Ship Navigation Safety Analysis

With many accidents of ships which meet the current intact stability criteria happened during the voyage, more and more people begin to pay attention to the ship’s intact stability. The International Maritime Organization is now drafting the second generation of intact stability criteria. It not only considers the impact of the static dynamics, more importantly, it takes into account of the impact of waves. Five failure modes are included and parametric rolling is one of them. The level 1 and the level 2 vulnerability criteria draft of parametric rolling has been basically formed. The related research are carried out based on the draft, this paper’s main contents are as follows.(1) The calculation process and the development of the vulnerability criteria of parametric rolling are researched. Based on the mixed programming technique of Visual Basic 6.0 and MATLAB, the calculation software of the level 1 and the level 2 vulnerability criteria of parametric rolling is developed. Compare the calculation results of vulnerability criteria of international standard model C11 container ship between this paper and cssrc, then the reliability of the software is verified.(2) Twenty-eight ships of different varieties are calculated. The rationality and applicability of the vulnerability criteria draft of parametric rolling are researched. The harmony between the level 1 vulnerability assessment and the level 2 vulnerability assessment is studied, and the relationship between the parametric rolling evaluate results and the initial metacentric height is researched, the relationship between the parametric rolling evaluate results and the natural rolling period is also researched.(3) 6400m3 LNG carrier is taken as an example to calculate its vulnerability criteria of parametric rolling. Based on the calculation results, this paper extracts some influential factors of parametric rolling and finds that enlarging the area of the bilge keels, lowering the height of the center of gravity within a certain range, increasing or decreasing the speed under some certain conditions and reducing the roll damping can reduce or avoid the risk of the occurrence of parametric rolling. Based on the influential factors, the ship’s navigation safety is analyzed according to the actual navigation situation, and some measures which can reduce or avoid the risk of the occurrence of parametric rolling are raised.