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Abstract
Predictions of full-scale ship resistance and powering are made for antifouling coating systems with a range of roughness and fouling conditions. The estimates are based on results from laboratory-scale drag measurements and boundary layer similarity law analysis. In the present work, predictions are made for a mid-sized naval surface combatant at cruising speed and near maximum speed. The results indicate that slime films can lead to significant increases in resistance and powering, and heavy calcareous fouling results in powering penalties up to 86% at cruising speed. The present estimates show good agreement with results from full-scale ship power trials.
Acknowledgements
The author gratefully acknowledges the financial support of this research by the Office of Naval Research. Thanks are also due to Mr Bill Beaver and Mr Zseleczky and to the referees for their many helpful comments and suggestions.
Notes
1. An alternative approach to ship resistance and powering prediction from scale model tests is to assume that the total resistance is comprised of wavemaking and viscous components (International Towing Tank Conference [ITTC], Citation1978). This is generally referred to as the ITTC-78 method. In this method, the viscous component is assumed to be due to both frictional resistance and pressure or form resistance. The ITTC-78 procedure explicitly accounts for the form resistance as a form factor multiplied by the frictional resistance. In the present procedure employed by the US Navy (e.g. Gillmer & Johnson, Citation1982; Woo et al. Citation1983), the form resistance is implicitly accounted for in the residuary resistance, and no form factor is used. It should be noted that the resistance and powering predictions from the two methods are generally comparable.