Stability Study Of Symmetric And Asymmetric Semi-submersible Crane And Accommodation Unit

With the quick development of ocean oil gas exploitation, the demand for marine engineering equipment increase greatly, large offshore engineering equipment and construction of the jacket means more large hoisting equipment. The people of the world’s growing material and cultural encourage the living environment of the sea improvement, so with excellent performance, strong ability against wind and no water depth limited semisubmersible offshore lifting and hotel platform are highly appreciated by of oil service companies.Stability is the most basic performance for the semi-submersible offshore platform and the most basic defence of people’s life and property safety. To the structure form of state, the purpose of this article is to study the impact of stability performance for the lifting and hotel platform whether the lower hull is symmetrical or not.At the moment, International Maritime Organization, American Bureau of Shipping and Det Norske Veritas all have set strict regulations on the stability of semi-submersible platform. Regulations of the three organizations are compared in three aspects as intact stability, damaged stability and loss of load stability, to study the similarity and difference between each other.First of all, according to its lower hull symmetric or not, build hydrostatic model A and B respectively and based on the same characteristic value, to build the wind model A and B, between the two wind model, calculation, analysis and come to the conclusion.Second, the stability analysis procedure was summarized according to stability regulations. As the intact stability, damaged and loss of load stability analysis for transit condition, survival condition, hotel condition, hotel condition and temporary condition is completed, the curve of allowable vertical center of gravity for model A and B is extracted.At last, Classify the loads of semi-submersible lifting and hotel platform, clarify estimation method, all lightship weight effect items and weight results of model A and B, and design load condition according to loading conditions philosophy and ballasting requirements, calculate and compare typical loading condition of model A and B, all the designed load conditions is checked to fulfilled the requirement of regulations.Comparing model A (asymmetric) and model B (symmetric) calculation results which have the same hydrostatic characteristics, no matter from the center of gravity height of limit curve, lightship weight, or the payload carrying quantity of normal (include transit and lifting) loading condition and more adjustable ballast water, for the lateral lifting semi-submersible lifting and hotel platform, if the lower hull is asymmetric, will get better stability performance than the symmetric form.