Metamodels for seakeeping assessment of fishing vessels

Abstract

The most significant goals of this paper are: (i) to provide additional insight on the influence of hull form parameters on seakeeping performance of typical Mediterranean fishing vessels; (ii) to develop efficient and reliable metamodels for fast and reliable evaluation of seakeeping performance in a multiattribute decision-making environment; (iii) to facilitate and speed up the selection of the design with the best possible seakeeping performance at conceptual design stage. To enhance the accuracy and applicability of predictions of seakeeping characteristics and to find out guidelines for design scope, new metamodels have been developed from an extended database of 57 cases, which comprehends the hull form geometrical data, heave (h), pitch (p) and vertical acceleration (av) rms values of both old 39 cases studied previously as well as new 18 cases of Mediterranean coastal fishing vessels previously analysed for resistance assessment. Main statistical parameters of the derived regression equations show a substantial improvement of statistical accuracy in h, p and av estimates, particularly when geometrical descriptors of forebody and afterbody hull form are included as independent variables. Statistical homogeneity of the N57 extended database was verified by cluster analysis of selected responses with classical hull form coefficients/parameters, and new descriptors data altogether taken as discriminant variables in two nucleus clustering analysis. Values of heave, pitch and vertical acceleration yielded by the metamodels have been compared to the ones determined by means of direct computations. Low residuals have confirmed reliability of the proposed prediction metamodels to determine since conceptual design stage seakeeping performance of fishing vessels with hull forms and main dimensions which could be included in the design space defined by the population forming the extended database.