A new slot structure to ensure both structural safety and constructional easiness has been developed. By FEM analysis of its static strength in a 280,000 DWT double hull VLCC and by fatigue strength test using a model, practical use of this new structure has been studied. Further, based on the fatigue strength test results for its structural elements, a fatigue strength evaluation criteria that can directly evaluate its fatigue strength under working load and has a good conformity with past data has been made. Then, the fatigue strength of the new slot structure adopted for a double hull tanker has been evaluated according to this criteria. As a result, it has been ascertained that the new slot structure is superior to the conventional one in the static strength and the fatigue strength and is applicable to actual ships.
