Abstract
An efficient hull form design needs to incorporate some prediction methods which will be able to predict the influence of hull form modification on the ship performance. This paper presents a new and simple prediction method for the form factor which relates directly to the hull form. Six flow-field parameters which have influences on the form factor are proposed on the basis of the result of double-model flow calculation and 3-dimensional boundary layer calculation around the hull form. A regression equation to predict the form factor is made by using 7 parameters (6 flow-field parameters and displacement-length ratio) and model test results in a towing tank. In order to adopt the minimum Akaike Information Criterion (AIC) estimate method in a regression analysis, 7 parameters are selected among many variations.
Predicted results for the form factor of full form ship at full load condition by the present regression equation show good agreement within 2% with tank test results. At ballast condition, predicted results show good agreement within 3%. Since flow-field parameters in the present regression equation act as intermediary between actual hull form and ship performance, a designer can easily obtain an information of how to modify the hull form according to the flow-field parameter in order to improve ship performance.
