1198. A Statistical Examination of Weight and KG Margin Values for U.S. Navy Surface Ships

Paper

Abstract

Effective weight and KG (height of vertical center of gravity above the keel) margins are an essential element of the U.S. Navy Weight Control Program. Margins are not only an engineering tool for making technical prediction, but are embodied in the fiscal processes as well. The need for improvements in margin determination was recognized when the weight control program was formulated in 1961. The first improvements came with establishment of a formal margin policy in 1963. The values, restricted only to weight at that time, reflected the best corporate engineering judgment based on scattered and, in many cases, unverified weight growths. Because the shipbuilding process is relatively slow (compared to aircraft, land vehicles and missile production), it has taken fifteen years to accumulate a data based considered reasonable for a statistical study of margins. The data used in this paper are the product of the weight control program margin accounting system and represent a substantial improvement over the data used in 1963. This paper discusses the derivation of the data and the selection of appropriate statistical methodology in order to update the existing weight margin policy and establish a KG margin policy.