Criterion of offshore jacket launching analysis

In the large offshore structure installation, a lunching process is considered one of the most critical operations. As the size of structure increases, it limits the availability of offshore crane facilities. So often large jackets are installed by launching method. This method is also utilized to other type of large structures offshore. As the structure approaches to the tilt beam in the launching barge, it reaches a critical load and there are parameters affecting on launching procedure. The major influential parameters are trim, draft of barge, center of gravity, center of buoyancy and reserved buoyancy of jacket. As increasing of trim and draft, structural loads tend to decrease. The trim is found to be more contributing than draft on structural load, therefore the trim should be increased so as to decrease structural loads and to avoid stalling of structure and submergence of stern. During the launching process, the distance between jacket and seabed should be investigated which differs from the amo unt of reserved buoyancy and launching condition of barge. In this paper, the effects of parameters on launching process are intensively examined by numerical modeling.