The paper gives the statistics about average accidents which took place in a certain province of East China from 1985 to 1986 and in all over the country from 1977 to 1985. By analyzing a large number of original records about average accidents, we summarize their causes and the serious results, and present an effective design technique to prevent ship-bodies from collision, Through plenty of research on ship-bodies deformations which result from colliding, substructure assumption is presented. It is the pr...