751. The Implementation of Weight Estimating and Weight Control Programs

Paper

Abstract

In the early sixties, the U.S. Navy established weight requirements which differed substantially from previously used practices. By means of a Contractors Design Weight Estimate and a negotiated and agreed upon Accepted Weight Estimate the Shipbuilder is contractually obligated thru a supplemental agreement to deliver the vessel with a displacement and vertical center of gravity which do not exceed the values of the Accepted Weight Estimate modified for contract modifications and weight and moment changes in the Government Furnished Material and within the limits of trim and list as given by the Contract Specifications. Furthermore, the Inclining and Accepted Ship Report is an INSURV item and if the limits of the adjusted Accepted Weight Estimate are exceeded the shipbuilder might have to take costly corrective action. As a result of the above requirements which are stated in detail in the General Specifications (1) and detail specifications, Shipyards have initiated Weight Control Programs during the Construction of Navy vessels and have extended their staffs engaged in Weight Engineering.
The problems shipyards face in hiring specialists for unusual projects, building up large engineering staffs during peak periods and subsequent reduction during slack periods can be solved by reiteration of the engineering and drafting facilities offered by a Design Agent. A Design Agent such as the J.J. Henry Co. is engaged in the Design of ships for NAVSEC and ship owners and has performed detail engineering for a great number of private and Navy shipyards. Thru the years, extensive experience has been obtained in the area of weight estimating for many types of merchant and naval vessels. This experience is the subject of this paper with emphasis on the comparison of weight estimating for merchant vessels and the Navy Control procedures.