Optimum Hull Structure
Simplified hull structure and enhanced structural strength
Web plates of main transverse members such as floor plate need to be fitted with stiffeners (a kind of reinforcement member) with required spacing to prevent the buckling of the structure. In VLCC's conventional double bottom floor structure, vertical stiffeners are directly fixed to every longitudinal frame by welding. In the Apple Slot structure, on the other hand, a combined stiffening arrangement of vertical stiffeners with necessary spacing (to ensure the rigidity of the entire floor structure) and horizontal stiffeners (to divide the floor plate between these vertical stiffeners) is adopted to prevent the buckling of the floor plate.
The Apple Slot structure ensures a higher structural reliability because it enables reduction of welding works at connecting parts between face plate of longitudinal frame and vertical stiffeners on the floor where the stresses are so high as to cause fatigue damage.
Further, because of reducing the number of vertical stiffeners and brackets connected to the longitudinal frame, the Apple Slot structure is advantageous in simplifying the structure and automating the construction process.