Modeling and Analysis of Ship Repairing Labor

Abstract

Labor cost is an important and sensitive issue in labor intensive industry. Ship repairing work is, by nature, labor intensive and not prone to automation. In normal ship repairing or routine maintenance of a ship, labor cost contributes the highest amount in the final invoice. This figure may go up to 70% of the total cost. This cost is directly contributed by labor (man-days) utilized for the ship repairing works. Owners and shipyards are always very keen for lowering the man-days value. Lesser man-days can directly be translated into the lower final invoice (for the owner) and higher productivity (for a shipyard), which can help the shipyard to stay in a competitive market. Ship repairing labor (man-days) and related information for 50 cargo ships of various ages, sizes and types were collected from a single shipyard. A multiple linear regression model was developed and analyzed using these primary data. Ship repairing labor was then expressed as a function of a ship's age, deadweight, type, and repairing works consisting of mainly hull blasting, hull painting, structural steel, and piping. The "method of least squares" was applied to estimate the regression coefficients. In this article, the authors have made an attempt to identify those independent variables that influence ship repairing man-days (the dependent variable) and their interrelationship. A mathematical model has thus been developed and proposed, as a guiding tool, for the decision maker to estimate a more realistic ship repairing labor (man-days) for ships to be under repair.