STRUCTURAL ANALYSIS OF A SUBMERGED COMPOSITE HULL, INTENDED FOR OIL RECOVERY FROM SHIPWRECKS

In the present work, the survivability of a submerged structure against hydrostatic loads, imposed by the operational environment, such as hydrostatic pressure due to depth, is presented. The structure under consideration is a component (Buffer Bell) of a larger system called DIFIS that recovers fuel from shipwrecks in order to prevent oil spills. This system was developed within the frame of an FP 6 EU project under the acronym DIFIS and relies on gravity forces to channel the spilled fuel flux towards a Buffer Bell-reservoir, 30m below the sea surface, by means of a light, easy to deploy and flexible structure that would stay in place until the pollution threat is eliminated. The Buffer Bell is a main element of the DIFIS system as it is the component that receives and stores the recovered oil and allows its transfer to surface vessels. It consisted of two parts; the Reservoir and the Floater. The Reservoir is a large tank used for the temporary storage of the recovered oil during the operational phase. The Floater is the part that produces the buoyancy force that holds the whole system in place and therefore its structural integrity is crucial for the operation of the system and the safety of the structure. During the final concept, the Floater is designed as a double hull structure made of steel plates and stiffeners. In the present analysis, an optimized structure made of GFRP and foam is proposed in order to reduce the steel’s hull weight. The structural analysis of the composite hull is carried out for the worst case scenario