Hull Optimization Research Articles

A Genetic Algorithm Approach to the Problem of Minimum Ship Wave Resistance

A genetic algorithm-based optimization method is proposed for an optimization of a ship hull from a hydrodynamic point of view. In the optimization procedure, the wave resistance has been selected as an objective function. The genetic algorithm is coupled with a computer program for solving the three-dimensional potential flow around a ship hull. The potential flow solver is based upon the well-known Dawson method. The optimization procedure has been applied to the Series 60 CB = 0.60 hull taken as a basis hull. The computational examples show the optimization ability of the proposed method.

Ship Hull and Machinery Optimization Using Physics-Based Design Software

Ship design software is applied to the study of improving the design of an existing cruiser. The focus of this paper is on exploring machinery configuration options that could significantly reduce the overall fuel consumption and, consequently, reduce the total weight and operating cost of the ship. The prime movers, most likely gas turbines, of the majority of the naval ships today are usually designed for maximum speed, which is much higher than the ship's cruise speed. In the case of the CG47, the shaft power required at cruise speed is only 16% of that at maximum speed. Consequently, the specific fuel consumption is 64% higher at cruise speed because the gas turbines are delivering only a fraction of their rated power. In this paper, auxiliary engines are introduced and their overall impact on ship design are studied. Four different machinery configurations, namely, CODOG, CODAG, COGOG and COGAG, are examined. Results show that as much as 34% fuel savings could be achieved and the overall reduction in total ship weight could be as high as 9%.

Effect of Hull Forms on Ship Motions and Optimization of Hull Forms for Seakeeping Performance

It is of importance to design a ship which has a good seakeeping performance in her sea-lane. It is, however, hard to say that an optimization of the hull form for seakeeping performance has been sufficiently carried out from the seakeeping point of view at the initial design stage of a merchant ship so far, because it has been difficult to make clear the seakeeping criteria and the correlation between the hull forms and the seakeeping qualities.In this paper the author derives the regression equation to estimate the correlation between the hull forms and the seakeeping qualities by applying the Bales' procedure to the container ships. He provides the guidelines to optimize the hull form for the seakeeping performance and the added resistance in irregular waves. The calculation is made to determine the hull forms in accordance with the above guidelines, and finally the optimized hull form is shown for the seakeeping performance and the added resistance. It is concluded that the present method is very easy and useful in the early stage of ship design for determining the dimensions of a new ship which has a good seakeeping performance and a small added resistance.

Analysis of Wave Resistance in the Design of the 12-Meter Yacht Stars & Stripes

During the design of the 12-Meter yacht Stars & Stripes, the design team placed great emphasis upon the minimization of all forms of hydrodynamic resistance: skin friction, lift-induced drag, form drag, and wave resistance. In this paper, the authors discuss methods used to measure, predict, and minimize the wave resistance of 12-Meter yachts. After a brief review of wave resistance theory, the authors discuss a method by which the wave resistance was determined directly from measured wave profiles. Numerical techniques used to theoretically predict the curves of wave resistance from the yacht designers' description of hull geometry are examined, and the predictions are compared with the experimentally determined wave resistance. Finally, the authors discuss hull optimization techniques, based upon the minimization of the theoretical wave resistance, which enable the yacht designers to develop hull shapes of minimum wave drag.

A Method for Optimization of Ship Hull Forms based on Wave-pattern Analysis Data

This paper presents a method for optimization of ship hull forms on the basis of wave pattern analysis.The method is primarily based on the assumption that a linear relation exists between the small difference of prismatic curves and the difference of the amplitude functions of the generated waves.Firstly wave analysis data are collected of several ship models with variant prismatic curves including the specified ship model. If the difference of prismatic curve, ΔCpj (ξ), and the difference of amplitude functions, ΔPj, ΔQj, between the specified ship model and the other ship models are known, the modification to be made for a designed ship, ΔCp (ξ), ΔP, ΔQ, can be expressed by the following linear equations : ΔCp (ξ) =∑ajΔCpj (ξ) (i) ΔP+iΔQ=∑aj (ΔPj+iΔQj) (ii) As for the coefficients, ajs, as the wave-making resistance coefficient, Cw, of designed ship model is to be derived by making use of ΔP and ΔQ in the equation (ii), the ajs are determined so as to minimize Cw.The author's method was verified to be successful in the case of being applied to the prismatic-curve series of the ship models with the same hull-form factors. Further study is under way towards extending this method to the case of ship models having different hull-form factors.

Pressure Hull Optimization Using General Instability Equation Admitting More Than One Longitudinal Buckling Half-Wave

Current design procedures often assume that the critical buckling shape in general instability contains only one longitudinal half-wave. This assumption may be incorrect for optimal hulls if what appears to be a questionable independent frame buckling constraint, often employed in pressure hull design, is relaxed. A method for predicting general instability admitting more than one longitudinal l half-wave is, therefore, adapted to an automated optimal design procedure for the synthesis of frame-stiffened, cylindrical, submersible hulls. Design studies demonstrate that substantial weight reductions are possible for hulls designed for conventional operating depths (around 1000 ft) if ultrahigh-strength steels are utilized.