Abstract
The possibility of interval extension between two dry docking is alternatively offered to the shipowners by classification societies. Although, for now, such a possibility is limited only to certain types of ships, a significant shift has been accomplished in accordance with today's technical and technological capacities. It is quite clear that not all shipowners will accept this option, as either five-year or even mid-interval might suit them well. The option introduces an economic benefit, but requires additional preparation to withstand the full interval without negative consequences, primarily related to the protection of underwater part of the hull. The relationship of economic benefits and the cost of investment to successfully pass the complete period gives a clear view to the shipowner for the decision of accepting an extended dry docking period between two consecutive dry dockings. This paper is presenting one of the approaches to calculate feasibility of prolonging dry docking interval. Calculation example represents an economic indicator, crucial for shipowner’s decision to accept prolonged dry docking interval. The paper presents an analysis of underwater hull condition for the vessel with a composite coating. It is based on a collection of actual data registered in the period of seven years. Significant data have been derived from the analysis, allowing basic set up for theoretical assessment as well as the real justification of extended dry docking period between two consecutive dry dockings of the vessel. Some of the presented facts, related to underwater composite coating, might be used for similar calculations.
Highlights
Dry docking of the ship is an integral part of the regular maintenance of underwater hull, propeller, bow-thruster, sea water chests, cathodic protection of the hull, rudder, etc
The graphs are presented to determine the trends of fuel consumption and ship speed (International Organization for Standardization, 2016) in the indicated specified period to find out whether it is possible to extend the interval between the two dockings without significant loss of ship speed or increase in fuel consumption at the end of the extended range
This paper undoubtedly proved the economic viability of the change to the prolonged interval, the particularities of each case should account
Summary
Dry docking of the ship is an integral part of the regular maintenance of underwater hull, propeller, bow-thruster, sea water chests, cathodic protection of the hull, rudder, etc. With the occurrence of the possibility to extend docking interval to the period of seven and a half years, applicable only for certain types of vessels, a discussion opens in which interested sides present arguments for and against, to reconcile opinions. It is indisputable that today's technology enables most of the inspections and the repairs of the ship's underwater hull in a floating condition (Hydrex Underwater technology, 2012), and it is quite justified to introduce extended docking interval. The efficiency of the ship’s underwater hull coating is quite challenging for the five-year interval of Dragan Bebić et al.: EDD – Economic Benefit Analysis of Extending Dry Docking Interval docking, and the extended interval complicates the problem. This paper deals with the extended interval of docking based on the analysis of actual data from the field
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