Fundamental experiments on motion analysis of deep-water risers for OD21 drilling vessel

The OD21 scientific drilling vessel of JAMSTEC, which is scheduled to be internationally operated from 2006, is planned to equip the 2,500 meters long riser string in the initial stage, and the 4000 meters class in the future. The operations of such deep-water riser strings as more than several thousands meters are still far from enough experiences, and the dynamic motions of the riser suspended from the surface vessel are not well examined. The authors carried out the 1/100 scale model experiments with using the visualization method to analyze the dynamic response of risers, and they obtained basic, but such important characteristics against the actual designs of deep-water risers as the longitudinal dynamic elastic response, the lateral motion induced by the parametric oscillation, and so on.