670. Determination of Weight, Volume, and Construction for Tankers and Dry Cargo Ships

Paper

Abstract

This paper presents a method, working charts, and substantiating data for obtaining selected design characteristics, component weights, functional volumes, and cost of construction of dry cargo ships and tankers. The method is substantially less time-consuming than the usual detailed ship design approachand is suitable for computer studies ofselected cases such as may be necessary in trade-off analyses. RAND Memorandum RM-3318-PR** dealt with these types of ships on a simplified basis, using the Maritime Administration’s weight and cost grouping system. This paper usesthe Navy weight and cost grouping system, and the data base has been expanded in quantity and detail of information. To develop the method and thedata, details ofcomponent weights and costs of a numberof ships were obtained from various sources. Distribution of volumes by functions were calculated from such information as boolets of plans and Bonjean’s curves. All of these data were analyzed and plotted in parametric form. Since the Navy system of grouping weights and costs was selected as the basis for all analyses, the data were reclassified from the familiar Maritime Administration 180-item weight system to the Navy 140-item weight system. The generally accessible weight information is usually published in the 3-component Marad or 7-component Navy system. Working charts showing the relationships of component weights, volume, material cost and man hours for the respective Navy weight and cost groups are presented in the body of the report. Substantiating data for these working sheets are presented in the appendixes ,which show the datapoints for the ship cases analyzed, and the rationale for determining the parametric relationships. The method presented in this paperis not intended to supplant the lengthyand more accurate methods employed by ship designers in preparation of designs or bids, but rather to provide a tool of first-order accuracy that will give quick solutions to those who must make dozens or even hundreds of ship design cases in the course of preparing a study. The method is useful to ananalysis of the effect on overall ship design of changing any, or several, parameter(s),e.g., propulsion type, hence weight ands peed, for a given value of power. It is ‘also useful to the system analyst to whom the ship characteristics and cost are but one of many essential inputs.