A Linear Programming Approach to Optimization of Ship Design and Construction Phases

Abstract

Labor cost savings can be obtained by considering the effect of design rework on the degree of overlap of the ship design and construction phases. Based on data from a shipbuilding case study, a linear programming (LP) model was developed to investigate the optimum overlap of the design and construction phases. Two scenarios were modeled. The case study's start-up period, which involved design and the construction of four ships, and a hypothetical small batch program to determine the degree of overlap and total hours required for a new shipbuilding program. In each scenario, the LP model found the optimum overlap period for design and construction and the associated total hours. In the first scenario, the analysis demonstrates that by reducing the amount of overlap between the design and construction phases, a reduction in construction direct labor hours can be achieved while obtaining the overall duration and scheduled completion times. In the second case, the analysis recommends a zero overlap policy between the design and construction phases to minimize total hours while achieving the overall schedule duration. When compared with the actual case study results, the zero overlap policy estimates an $8 million saving. The analysis supports the policy to complete design activities with construction-dependency relationships before starting construction.