A comparison of the motions of trimarans, catamarans and monohulls

Abstract

The seakeeping motions of catamarans and trimarans are computed using a time domain seakeeping method, which has been accurately validated across a range of Froude numbers from 0.2 to 0.8. Both vertical and horizontal accelerations are evaluated. No motion controls are fitted. It is found that the rolling of a trimaran increases as the buoyancy in the outboard hulls is reduced, and exceeds the rolling of an equivalent catamaran by a factor of two when 5% of the total displacement is in the outboard hulls. In head seas, the greater length of the trimaran reduces the maximum heave motions relative to wave height as a consequence of the reduced length-based Froude number.

Keywords:

• Seakeeping
• wave response
• ship motions
• fast ships
• wave loads

Additional information

Notes on contributors

M R Davis

Michael Davis is a professor of engineering at the University of Tasmania. Mike completed his bachelors degree in aeronautics and doctorate in sound and vibration at the University of Southampton. He subsequently worked at the de Havilland Aircraft Company and the Royal Aircraft Establishment, Farnborough, before joining academic staff in the Department of Fluid Mechanics and Thermodynamics at the University of New South Wales.

Mike has also spent periods in visiting positions at the University of Cambridge and the Massachusetts Institute of Technology. He is currently working in the area of ship dynamics and propulsion, with particular reference to high-speed ship motion and wave loads, and has published and acted as consultant in heat transfer, fluid dynamics, vibration and noise.

Mike is a Fellow of Engineers Australia, and a former President of the Tasmania Division and Chair of the Mechanical Engineering College. He is also a Fellow of the Royal Aeronautical Society and past member of Australian Council of Professions.

D S Holloway

Dr Damien Holloway is a lecturer at the University of Tasmania in the areas of stress, structural analysis and dynamics. He completed a BE(Hons) in civil engineering at the University of Tasmania in 1992, graduating with a University Medal, followed at the same institution by a PhD in ship hydrodynamics, completed in 1998. He has held postdoctoral positions in both mathematics (free surface groundwater problems) and engineering (ship hydroelasticity), and worked as a consulting civil/hydraulic engineer.