EARLY STAGE WEIGHT AND COG ESTIMATION USING PARAMETRIC FORMULAS AND REGRESSION ON HISTORICAL DATA

摘要

Estimation of weight and center of gravity is an essential task in the design phase of a vessel, and the quality of this work will be crucial for the success of the project. It is important to have the best possible estimate for total lightship weight, but when it comes to construction and installation there will be a demand for detailed budgets. A certain detail level for the weight budget will also make it easier to find the reasons for any deviations that may occur during the monitoring phase. The use of parametric estimation based on several reference ships and regression lines has traditionally been characterized as too demanding, because of time demands as well as complexity. This article will describe some assumptions and methods that make it possible and preferable to use parametric estimation on a regular basis when designing and building a ship, either by the use of built-in formulas and graphs found in spreadsheets, or by the use of database related weight control systems like ShipWeight. This article will discuss topics like breakdown structures, methods, selection of coefficients, selection of detail level, reporting and exporting of results, together with design changes and re-estimation. Runar Aasen is one of the founders and technical sales manager of BAS Engineering, a SAWE corporate member. Mr. Aasen has a Master of Science Degree in Ship Design, has been extensively involved in the development of weight engineering software and user support for the last fourteen years, and became a SAWE Fellow Member in 2006. Since 1996, BAS Engineering has provided ship designers and builders around the world with naval architecture and mass properties support. BAS Engineering's ShipWeight software entered the US market for the first time in 1998 and has since been adopted by major US shipyards and designers. Stein Bjflrhovde is one of the founders and head of development of BAS Engineering. Mr. Bj0rhovde has a Master of Science Degree in Ship Design, and has been developing the weight engineering software ShipWeight since 1993. He has also been involved in development of other weight control software, in addition to being a consultant doing weight estimation and monitoring in the offshore industry. He has more than 15 years experience in weight estimation of new ship designs for several Norwegian and international ship designers and yards.