Experimental Analysis of Surface Geometry, External Damping and Waves on Semisubmersible Vortex Induced Motions

Semisubmersible Vortex Induced Motions have been studied extensively at model scales, and observed under field conditions. VIM response is of particular concern in evaluations of Steel Catenary Riser (SCR) fatigue damage. Historically, most of this experimental work was done with bare models, without much effort to represent actual hull surface characteristics. In this paper, the effect of these appurtenances, tow direction and wave action is investigated. There is also an examination of vortex induced yaw response. VIM response is assessed using motion trajectories, dominant response direction, and amplitudes and periods of response. Variations in these quantities are also investigated.