Abstract：A numerical model of the large carrying capacity crane ship with the fully revolving topside is represented in the article. The model provides a way of determining the main crane ship’s elements using version design approach with further system optimization. The principal analytical equations are set up in the article to solve that problem. Relationship between ship characteristics and elements is established from the point of view of providing initial stability. Once the model has been verified, an investigation of the influence of relative breadth and block coefficient on the displacement of the large carrying capacity crane ship in operating condition is performed. Based on the results of that investigation, the conclusions as to insufficiency of the condition of providing initial stability for system optimization of crane ships are made.

Keywords: numerical model; design of crane ships; systems analysis; crane ship; crane topside;

1. Introduction

The most typical feature of the ship design process is the search for compromise solutions enabling designers to reach the highest efficiency of the ship and meet numerous and mutually contradictory performance requirements, which is the main principle of system optimization of ships. As a matter of fact, optimization is the essential

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1877-7058 © 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of DAAAM International Vienna

doi:10.1016/j.proeng.2015.01.470

condition for any ship development, and optimization problems are solved at all stages and levels of the ship design [1].

The ship design theory deals with a selection of design solutions for the ship as a whole. A version optimization approach is the main method of the ship design theory. The version optimization approach is based on a selection of the best ship version out of a set of previously designed versions with systematically varying elements. Such sets allow plotting the graphs of parameters characterizing various qualities of the ship and her effectiveness as a function of elements being optimized. The complete implementation into the design of those system approach principles, which require that the design of any sub-systems and facilities should be performed in compliance with the unified requirements of optimization of the ship as a whole, can be achieved only in case of simultaneous optimization of ship’s elements and sub-systems as a single problem. Let’s denote the set of ship’s elements defined at the initial stage of design development as a vector of elements x={xi}, iI, where I is the set of elements. We will include into it such parameters as principal dimensions, block coefficients, amounts of solid and liquid ballast, etc. Similarly, let’s introduce vector xk={xkj} as a vector of variables characterizing the k-th ship sub-system (with kK, where K is the set of sub-systems, and jJk, where Jk is the set of variables of the k-th sub-system). Examples of sub-systems are as follows: the hull, power plant and electric-power plant, hydrodynamic facilities, ship arrangements, systems, etc.

If the function f(x, xk) is available for quantitative estimation of the efficiency of the ship being designed, and qualities of the ship (i.e. buoyancy, storage capacity, stability, etc.) and those of her sub-systems and facilities can be estimated with the use of functions gS(x, xk) and gSk(x, xk), respectively, then the optimal ship design problem can be formulated in the following way: determine such x and xk, which satisfy the below conditions:

Where bS, bSk = normal levels of allowable values of a specific quality; S, Sk = sets of requirements for  qualities of the ship and those of her sub-systems.