Performance Analysis and Prediction of High Speed Planing Craft

Abstract

A comprehensive and critical review of literature pertaining to the study of planing craft is given within this work. This study includes monohull design, analysis and performance prediction for flat water; many features of the planing characteristics, including dynamic stability, the use of stepped hullforms, re-entrant transoms and flow characteristics are detailed. Work on the rough water seakeeping analysis of planing craft is also given, and furthermore, literature pertaining to planing catamaran design and performance prediction, and on the ground effect is cited. Mathematical modelling approaches are discussed and it is explained that there is still much progress to be made in this area before accurate and reliable analytical prediction methods become available. The method of matched asymptotic expansions and also a proposed force-mathematical model are shown to be particularly suitable to the prediction of planing craft forces and moments, the first method being highly analytical and the latter requiring a semi-empirical approach to be adopted. A discussion is given of the physical phenomena responsible for the characteristics of planing craft and their interrelation. It is also discussed how modem craft are attaining higher and higher speeds, and a result of this is that the dynamic characteristics of the craft, including the flow conditions, are substantially different to those of more conventional craft. This modem very high speed regime of planing has been analysed and identified in this study under the new title of 'Alto-planing'. Further discussion of planing craft form and design concepts are persued, including details of the design of catamarans and more novel forms. A new computer-based prediction method is presented, which includes prediction methods for trim tabs and an aero foil. The ability of the program to allow the designer to vary given inputs of the hull data is explained, and a systematic variation of all the input characteristics is detailed. An optimisation procedure is offered and it is observed that this new prediction method can provide the designer with as much data as required for analysis of the form, a distinct advantage over current planing craft prediction software. Validation is undertaken by comparison with data from trials results, model test data and comparison with other prediction techniques. A discussion of current prediction methods is given. Finally, the aerodynamic characteristics of alto-planing craft are researched in detail, by means of a systematic series of model tests. Analysis of the results have extended the previous empirical limits and have furthermore segregated and quantified the components of the aerodynamic effects, including the aerodynamic resistance and the change in hydrodynamic running conditions due to the aerodynamic effects. An enhanced and novel prediction method is given, which is used to provide illustrative examples of the aerodynamic characteristics of alto-planing craft.

Date of Award	Dec 1994
Original language	English
Awarding Institution	University of Plymouth