A Study On Vulnerability Criteria For Ship Parametric Roll

Stability is an important aspect of ship navigation safety, especially for ship stability in waves which is complicated because of its multiple degrees motion. The current intact stability criteria is based on the hydrostatic theory, which is simple in application but can not meet the requirements of ship safety reliability. Therefore, the IMO is working on the establish of second generation intact stability criteria based on the hydrodynamic theory. The second generation intact stability criteria takes five kinds of stability failure modes into account when ships are sailing in waves and parametric roll is one of the five stability failure modes. The SDC,newly set up by IMO, issued draft criteria for parametric roll which coordinates all the proposal submitted by member countries. The draft criteria mainly introduced the working process of vulnerability criteria for parametric roll, but didn’t give definite conclusion for some details. Based on the above, the article works on the following aspects:(一) According to the current draft criteria for parametric roll, this article developed a computing system by using Visual Basic and Matlab.(二) This article calculated all the parameters of C11class containership related to draft criteria for parametric roll and validated the correctness and reliability of the program. Then this article calculated parameters of other vessels related to draft criteria for parametric roll.(三) After sample calculation, the article try to make proposals to improve the criteria. The article makes proposal on the sample points which are used to fit the curve representing the relationship between wave height and roll amplitude. Then, the article validate the proposal above by calculating parameters related.(四) At last, the article points out other problems in the draft criterion and make proposals in the future research.