University of Tasmania, Australia

Severe dynamic asymmetric structural loads on large high speed catamarans

Hobart based shipbuilder, Incat, builds some of the world’s largest and fastest high speed aluminium catamaran ferries. Critical to the success of Incat’s vessels has been their ability to operate at high speed in heavy seas, and Incat’s position as worldwide leaders in their market niche has been assisted over more than two decades by ongoing collaborative research with the University of Tasmania’s School of Engineering.

A long term goal is to optimise the ship structure, minimising weight without compromising integrity at critical locations. Past recent research in this area has sought to quantify the loads exerted during a slam (severe wave impact) event. Structural vibrations following a slam (known as “whipping”) are known to significantly modify the internal forces as determined by a quasi static analysis, and their effect has been partially quantified through testing of a 2.5m hydroelastic model, full scale strain measurements, and dynamic finite element analysis.

The current project aims to extend this work by relating the asymmetric slams to the asymmetric design loads within the superstructure connecting the two hulls (referred to as “pitch connecting moment” and “split loads”). This has the capacity to influence design codes and to provide a more rational framework for the determination of design loads in similar ships.