Superposition and interchangeability of design characteristics of the multipurpose ice-going ship in determining their optimum values

  Objectives  This paper aims to propose an approach for optimization of the multipurpose ice-going ship characteristics and design particulars, considering methodological interdependence among these values. The ship particulars do not appear to be independent in the systemic sense, and any of the characteristics of the size could be predetermined by the definite approximation.

  Methods  The methodological approach means the selecting an independent characteristic which is varied in the next for searching its optimal value on the criteria used. It is taken into account the methodological property of superposition of design characteristics as to find the optimal values of the independent design characteristics, the associated balance proportions with the rest of the ship size characteristics and the associated parametric dependences with the design particulars, that means as well determining in the initial approximation of the rest characteristics of ship size and design particulars. Since in the subsequent design stages the refinement are carried out in the narrow intervals of their variation of the approximate values of rest ship size characteristics and design particulars, which were found approximately at the initial stage, corresponding to definite inaccuracy of their approximate determination at the initial stage. The improvement of the originally found values within the inaccuracy does not exert the noticeable influence on the optimum value of the independent design characteristic, determined at the initial stage, serving as the design constraint in the improving of the values of the rest characteristics, as well as its design particulars, found approximately in determining of optimal value of independent design characteristic.

  Results  The property of superposition in finding optimal design characteristics and particulars means the possibility of their independent sequential determination if the characteristics found in the previous design stages and particulars are used as the design constraints in subsequent stages.

  Conclusions  Initially the characteristics of ship size are determined with the allowance of design constraints, and then the design particulars are sought, while the design constraints are found for ship characteristics.