Methods of improving the level of pre-contract design definition and the quality of information relating to steelwork are described. This information is combined with a comprehensive database of manufacturing process information to provide a system for estimating the work content of the main structural steelwork of ships such as roll-on/roll-off vessels. Procedures are described which facilitate consistent estimates to be made while minimizing data-handling requirements and increasing the flexibility of the method at the concept design stage. Applications are described which demonstrate the use of the system in investigations which examine the variation of factors which influence labor cost. The factors examined include the effect of changing midship block breakdown and length of productive day. Suggestions are made as to how the system can be used to assess the importance of those factors which may improve overall yard production efficiency and assist in the planning function.