DRY-DOCKING TIME AND LABOUR

Abstract

The duration of stay of a ship in a drydock depends on the scope of routine underwater (submerged portion of the ship’s hull) repairing works (dry-docking works only) to be carried out. More specifically, the repairing works that are affected by outside water. These are, mainly, hull cleaning, coating (blasting and painting), rudder, propeller, stern tube aft seal, hull anodes, ICCP, sea valves, sea chests, tunnel thruster(s), bottom plugs, underwater structural steel (bottom and shipside) and so on. These dry-docking works dictate ships’ dry-docking time (days) and labour (man-days). Then what about the deadweight, age and type? Do these have any impact on dry-docking time and labour? An attempt has been made in this article to examine if there exist any possible relationship between a ships’ dry-docking time and its labour, and deadweight, age and type. Dry-docking time and related information for 586 cargo ships and dry-docking labour and related information for 50 cargo ships of various deadweights, ages and types were collected from a single shipyard. These were analyzed and presented in both tabular and graphical forms to demonstrate the possible relationship between dry-docking time and labour, and deadweight, age and type of ships. Ships’ dry-docking time and labour are very vital for both the ship owner and the shipyard because various charges in drydock are many folds higher than that at quay- side. As such, the reduction in ships’ dry-docking time and labour contributes in saving for the ship owner and increases the earning for the shipyard. A proper estimation of ships’ dry-docking time and labour can achieve this. In order to do so, the past information/data about ships’ dry-docking time and labour may serve a practical guide to prepare an achievable time and labour planning for dry-docking works. In this article, the authors have attempted to identify the independent variables that influence ships’ dry-docking time and labour (dependent variables) and suggested their possible inter-relationships. The inter-relationships between the independent variables (deadweight, age and type) and dependent variables (time and labour) appear to be linear.