Impact of Linearization of Bilge Keel Damping on the Early Assessment of Vessel Operability

This paper investigates the benefits of a method whereby roll damping is assessed for each sea state in a given scatter diagram. Particular emphasis is given to the quadratic damping induced by the vessel bilge keels. For each sea state in a scatter diagram, an iterative process is used to obtain a sea state dependent linearized bilge keel damping. This paper shows the impact of such a refined method on the evaluation of operability for a generic vessel. It also provides a comparison with simpler operability assessment methodology both in terms of overall vessel operability and limiting operational sea states for typical scatter diagrams and operability criteria.