1606. Review of Ship Specifications for Weight Latitudes
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Paper
Abstract
In recent years, ships’ weight estimates have experienced significant weight growths as evidence by the difference between Contract Design Weight Estimates and Final Weight reports. In an attempt to reduce those differences, an investigation was undertaken to identify major contributing factors. One of those factors, associated with development of ship specifications to performance oriented requirements, was identified to be the latitudes provided shipbuilders in the ship’s specifications. Performance oriented specifications tend to permit latitudes which usually result in weight variances.
This paper addresses and attempts to quantify the weight and associate KG impacts of those specification latitudes. Thirty-two SWBS elements, where significant weight growths have occurred and where performance oriented specifications exist, were selected for review. Three ship designs reflecting present design philosophy latitude weight/KG variance of 1.73% to 2.64% of lightship weight, and an associated 1.41% to 2.09% of full load KG exists.
In order to significantly increase the chances of precluding the occurrence of these specification latitude weight variances on future designs any one or a combination of the following three actions can be taken: revise specifications to eliminate or reduce latitudes; incorporate latitude weight variances in estimates for affected three-digit SWBS elements; and or revise weight and KG margin values to account for latitude weight variances.
In summary, this paper documents the weight variances due to the latitudes in the ship specification for the 32 SWBS elements investigated. The results contain several significant findings and recommendations. The prime objective of this study was to identify areas where revisions to the ship specifications can be made in order to be more specific and reduce the latitudes provided to the shipbuilders. If revisions the specifications can no be made in initial weight estimates.
