Investigation into the vertical motions of high speed planing craft in calm water and in waves

Blake, James Ian Richard (2000) Investigation into the vertical motions of high speed planing craft in calm water and in waves. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

An analysis of the dynamics of a series of hard-chine constant deadrise planing craft, operating in calm water and in waves, is investigated through the development and application of two numerical models. The basic equation for hydrodynamic lift is derived from the consideration of an unsteady perturbed potential flow associated with the motion of a rigid body moving without circulation in an infinite fluid. Through a slender body strip theory analogy, the total vertical body forces and moments are derived. The solution to these equations of motion are solved within the frequency domain for the linear problem of time-invariant hydrodynamic coefficients, and within the time domain for the non-linear hydrodynamic coefficients.

Both the linear frequency domain model and the non-linear time domain model are validated against previous experimental and theoretical research. Both models are used to investigate the effect of parametric variation on craft stability in calm water. The non-linear model is applied to predict vertical craft response in regular and irregular waves and to investigate the effect of varying design parameters. Frequency dependence of added mass and damping is accounted for, and the consequences of this inclusion investigated.

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