Regression Analysis of the Ridgeley-Nevitt Trawler Series Resistance

Abstract

There are few numerical methods available for the prediction of resistance of hullforms with fine entrances and broad, flat sterns, typical of tugs, trawlers and offshore supply vessels. The field narrows even further for those hullforms having high displacement/length ratios. Ridgeley-Nevitt’s trawler series data caters for high displacement-length ratios up to 500, but the residuary resistance data are only available in the form of two-dimensional contour plots at each speed/length ratio, and determination is time consuming.

Data were therefore lifted from each of the contour plots and regression analyses completed, resulting in polynomial expressions for the residuary resistance at each of the speed/length ratios. The expressions are in terms of the prismatic coefficient and displacement/length ratio, giving good results compared to the contour plots and providing fast evaluation of the residuary resistance component.