### Hydrodynamic effects on fast monohulls or catamarans travelling through the critical speed in shallow water

#### Abstract

The speed of linear waves in shallow water approaches a constant value as the wavelength becomes large relative to the water depth. For ships travelling in shallow water, this speed is known as the `critical speed' and acts as a barrier, similar to the speed of sound for aeroplanes. The possibility of travelling at transcritical and supercritical speeds is discussed for existing monohull and catamaran ships. We explore the predicted linearised flow around a ship as it approaches the critical speed, and the singularities that result. Experimental results show the actual flow patterns that occur at ship speeds close to the critical speed, for monohulls or catamarans, in open water or confined channels.

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#### Keywords

ship; hydrodynamics; transcritical

DOI: http://dx.doi.org/10.21914/anziamj.v51i0.2635

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