Hull Form Optimisation of Fishing Vessels With Respect to Seakeeping

[摘要] The aim of this thesis is to formulate a relationship between the geometrical characteristics of a series of fishing vessel hull forms and the seakeeping qualities of these vessels. In addition a statistical relationship between these hull forms and added resistance and calm water resistance characteristics was developed. The selection of ship motion theory is an important task to determine the seakeeping performance of fishing vessel hull forms. The first motion prediction method considered is a two-dimensional strip theory which predicts the motion responses in six degrees of freedom for a ship advancing at a constant speed with arbitrary heading in both regular and irregular seas. The second option considered is a three-dimensional translating pulsating source distribution technique associated with a cross-flow approach for taking viscous effects into account Numerical computations were carried out using both theories for five chosen fishing vessels. It is found that the two-dimensional theory gives results with reasonable accuracy and with less Central Processing Unit (CPU) time compared with three dimensional theory. Experiments were carried out to determine the seakeeping and resistance characteristics of a typical Black Sea fishing vessel. These experiments yielded a useful set of data for the validation of theoretical methods. The strip theory results, in general, show good agreement with the experimental data as well as with the three-dimensional theory. It is concluded that the strip method is a reliable tool to predict the dynamic motionresponse values of a fishing vessel hull form. In comparison with the three-dimensional source distribution method, this procedure has an advantage in that less computer time is required. The generation of a systematic series of geometrically similar hull forms is of fundamental importance when seeking an optimal design with respect to the seakeeping characteristics. In this study a series of fishing vessel hull forms was generated from different parent hull forms. Numerical computations using the strip theory were carried out to determine the seakeeping performance of this series of hull forms. The main seakeeping parameters such as motions and accelerations were computed using the sea conditions specified for the Black Sea. The relative magnitude of these responses was related to hull form parameters by Bales' method. A regression equation with respect to hull form parameters was evaluated. An optimisation procedure based on seakeeping assessment was developed, and used to obtain two optimum hull forms whose geometrical characteristics lay within the range of the investigated series. These two optimum hull forms give superior seakeeping performance compared with the corresponding parent hulls. The resistance characteristics of the optimised hull forms were also evaluated.

[发布机构] University:University of Glasgow

[关键词] Naval engineering