There are several instances prescribed by chapter 15 - - catamaran structure supplement prescript in ccs " freshwater ship class and building criterion " which need to be calculated directly 中国船级社《钢质内河船舶入级与建造规范》中第15章双体船船体结构补充规定中指出具有船长大于60m等情况的双体船应由直接计算确定结构尺寸。
