Article

Modeling the Dry-Docking Cost - The Case of Tankers

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Abstract

Dry-docking is an integral part of a vessel's life. With a frequency of approximately 30 months, flag legislation and classification society rules bring the vessel to a shipyard's dry-dock for an intermediate or special survey. Dry-docking cost is a significant element of the ship's operating cost and is always presented as a six or seven figure amount. This paper, for the first time in the literature, unveils the determinants of dry-docking cost and hence equips the decision maker with a valuable tool for the cost side of his ventures. We have collected 414 cases of ship repairs from one of the biggest ship repair yards of the Persian Gulf, over a time span of 4 years. Making use of this primary database, we develop a simultaneous equations model and express dry-docking cost as a function of ship type, size, and age. Other important determinants are also incorporated into the model such as upswings or downswings in the shipping cycles and the shipping company's capacity as an effective negotiator. The method of estimation is Generalized Method of Moments and our results shade light on an issue, which has never before been effectively dealt with, given its immense practical significance for the decision maker.

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... There are many studies about financial implications on operating expenditures, fleet maintenance cost from various viewpoints, and global market condition, notably oil and gas prices. Very recently, one paper (Apostolidis et al. 2012) highlighted the dry docking cost for tankers. This study explores and identifies the relationship between the dry docking cost and other variables responsible for dry docking cost. ...
... Data analysis of 101 crude oil tankers of various ages, deadweights, their respective quantity of repair works like hull coating, piping, structural steel, and tank coating suggest that all these items (variables) have a positive influence on the total duration of repairing time. It is very much consistent with the literature on dry docking cost for tankers (Apostolidis et al. 2012). ...
Article
Ship repairing (hereinafter referred to as repairing) time, duration of stay of a ship in a shipyard (also a slipway or a floating dock), is a part of the routine maintenance schedule of a ship, mainly required by the classification societies and the flag states. With an interval of approximately 24‐30 months, the regulations of both the flag state and the classification society call for a ship to carry out docking survey, intermediate survey, or special survey (once in 5 years), depending on the age of the ship, in a shipyard/floating dock/slipway (hereinafter referred to as a yard). It is mandatory to fulfill the requirements and comply with the rules and regulations for maintaining statutory certification. Owners and yards always try to reduce the repairing time to reduce the loss of income (for an owner) and maximize the annual turnover through handling more ships (for a shipyard). Repairing time and related information for 600 cargo ships were collected from a single shipyard. A multiple linear regression model was developed and analyzed using these basic data. Ship repairing time was then expressed as a function of a ship's age, deadweight, repairing works of mainly hull coating, piping, structural steel, and tank coating. “Method of least squares” was applied to estimate the regression coefficients. In this article, the authors have made an attempt to identify the number of those independent variables that influence repairing time (the dependent variable) and their interrelationship. A mathematical model has been developed and proposed, as a guiding tool, for the decision-maker to estimate a more realistic ship repairing time for the fleet maintenance.
... Data analysis of 50 cargo ships of various ages, deadweights, types, and repair activities suggest that all these items (variables) have a positive influence on the total ship repairing labor (man- days). It is very much consistent with the literature on the dry docking cost for tankers ( Apostolidis et al. 2012). ...
... Despite the unavailability of sufficient literature on ship repairing labor (man-days) in particular, there are already some works done on ship repairing activities and related fields. Apostolidis et al. (2012) investigated and highlighted on the dry docking cost for tankers. This study explores and identifies the relationship between the dry docking cost and other variables responsible for dry docking cost. ...
Article
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.
... The second type of cleaning operation takes place when the vessel is in dry-dock for a special survey, roughly every fifth year following delivery. The special survey is a mandatory requirement imposed by the vessel's classification society and flag state administration in order to renew the vessel's safety and environmental certificates and remain eligible for insurance (Apostolidis et al., 2012). Certain periodic maintenance operations can only be performed when the vessel is in dry-dock, including the cleaning, sandblasting and coating of the hull with new antifouling paint. ...
... Certain periodic maintenance operations can only be performed when the vessel is in dry-dock, including the cleaning, sandblasting and coating of the hull with new antifouling paint. The total cost of drydocking is substantial, ranging from USD 1.2 to 1.6 million for tankers, depending on vessel size (Apostolidis et al., 2012). ...
... The dry-docking duration estimation model using the numerical ant-colony decision tree algorithm was introduced by Surjandari et al. [5]. Apostolidis et al. [6] developed the dry-docking cost estimation based on the equation model which expresses the dry-docking cost as a relation among the ship's type, size and age parameters. The relation between the vessel's data such as deadweight, age and type, and dry-docking time and labour was researched by Dev and Saha [7]. ...
... The virtual DMU needs to be better (at least not worse) than DO o . The constraints (2) to (5) create the DEA CCR model, and the DEA BCC model is created using constraints (2) to (6). The Equations (7) and (8) express the input excesses and the output shortfalls, i.e., "slack" vectors: ...
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Newbuilding dry-docking is a part of the shipbuilding manufacturing process, common for vessels built on slipways. The subject of this research is steel-built vessels intended for non-restricted sea-going navigation. Based on former experience, the necessity of the dry-docking projects measurement has been noted as a managerial tool for performance estimation and project comparison. The dry-docking project is a complex task which includes the first self-propelled sea passage and the transfer of the manufacturing process to a remote place. The dry-docking result is a surveyed and coated vessel ready for sea trials and five-year service until the next dry-docking. This paper deals with a model which enables process measurement using the analytic hierarchy process (AHP) method for qualitative data related to the dry-docking places and data envelopment analysis (DEA) for quantitative data related to the vessels’ technical and cost data. The modelled data are collected from the completed dry-dockings, and the twenty-nine studied vessels represent the decision-making units (DMU) used in two-step process measurement calculations. The obtained results can distinguish the efficient DMUs, which create an efficient frontier as benchmarks or “the best practice units” in the given DMU set. For the non-efficient DMUs, the efficiency score and rate of improvements needed to reach the efficient frontier will be calculated, and the sources of inefficiency will be recognized.
... In general, the ballast system consists of pipelines and pumps for receiving and pumping liquid ballast to perform the necessary ballasting, as well as to align or create an artificial list (list system) and trim (trim system) when performing cargo handling, floating in ice, in emergencies, etc. [1][2][3][4][5]. ...
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The paper is dedicated to the development and study of information system for automatic planning of liquid ballast distribution. The given computer system allows to calculate the current values of the operating variables of the ballast systems of floating structures and vessels of various types when performing different technological operations in the real time mode. The developed algorithmic support and software as well as human-machine interface of the information system gives the opportunity to obtain current information about the operating parameters of the ballast systems when controlling the distribution of ballast in various operating modes of the floating structures. The effectiveness study of the proposed information system for automatic planning of ballast distribution is conducted on the example of a real floating dock. The obtained calculation results confirms the effectiveness of the developed information system.
... In the overall maintenance cost, a significant part is on the dry-docking cost CDD. It has been estimated as [25]: ...
Article
For the natural gas transportation, several technologies can be applied, having different effectiveness and costs depending on the analysed case. The Mediterranean Sea is presenting a typical scenario where compressed natural gas (CNG) transportation is particularly attractive compared to liquefied natural gas (LNG) and pipelines, not only for stranded gas shipping but also for transportations cases where CNG is usually representing the most economically convenient solution. Approaching the design of a CNG ship is not an easy task, since the pressure vessel (PV) technology is strongly influencing the ship layout and hull form. Here an enhanced conceptual design method is adopted; taking into account the economic-financial issues together with logistics, in order to determine the best fleet composition selecting the best ships for the selected scenario. The ships composing the fleet are supposed to load/offload the natural gas on buoys; hence, dynamic positioning (DP) will also be considered as an attribute in the evaluation of alternative designs. As final outcome of the enhanced concept design process it will be possible to speed up drawing of the preliminary lines plan and general arrangement plan of the sister ships composing the fleet.
... This paper also provides a quantification and appreciation of the resulting cost benefits experienced by each participating shipyard. Apostolidis, A., Kokarakis, J. and Merikas, A. (2012) investigated and highlighted on the dry docking cost for tankers. This paper explores and identifies the relationship between the dry docking cost and other variables responsible for dry docking cost. ...
Conference Paper
Full-text available
Ship repairing time, duration of stay of a ship in a shipyard (also a slipway or a floating dock), is a part of the routine maintenance schedule of a ship, mainly required by the classification societies and the flag states. With an interval of approximately 24 to 30 months, the regulations of both the flag state and the classification society call for a ship to carry out docking survey, intermediate survey or special survey (once in 5 years), depending on the age of the ship, in a shipyard/floating dock/slipway. It is mandatory to fulfil the requirements and comply with the rules and regulations for maintaining statutory certification. Ship owners and shipyards always try to reduce the repairing time to lessen the loss of income (for an owner) and maximise the annual turnover through handling more ships (for a shipyard). Labour cost is an important and sensitive issue in labour intensive industry. Ship repairing work is, by nature, labour intensive and not prone to automation. In regular ship repairing or routine maintenance of a ship, labour cost contributes the highest amount in the final invoice. This figure may go up to 70% of the total cost. This cost is directly provided by labour (man-days) utilised for the ship repairing works. Ship 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 ship owner) and higher productivity (for a shipyard), which can help the shipyard to stay in a competitive market. Ship repairing time (days) related information for 600 cargo ships and ship repairing labour (man-days) 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 analysed using these primary data of time and labour each. Ship repairing time was then expressed as a function of a ship’s age, deadweight, repairing works of mainly hull coating, piping, structural steel and tank coating. Similarly, ship repairing labour was then expressed as a function of a ship’s age, deadweight, type and repairing works of mainly hull coating, piping, structural steel and tank coating. “Method of least squares” was applied to estimate the regression coefficients. In this paper, the authors have made an attempt to identify the number of those independent variables that influence ship repairing time and labour (the dependent variables) and their inter-relationship. A mathematical model has been developed for both time and labour and proposed, as a guiding tool, for the decision maker to estimate a more realistic ship repairing time and labour for ships to be under repair.
... Dry docking including BWTS retrofitting of vessels of approximately ten years of age and with a ballast capacity of approximately 30.000 m 3 takes about one month [17,52]. For vessels of that size and age, the usual dry docking time is between 12 to 15 days [53], meaning that the dry docking period is doubled. From September 2017 to September 2022, 9.000 vessels annually will need to install a BWTS. ...
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The International Convention for the Control and Management of Ships’ Ballast Water and Sediments was adopted in February 2004 and it was ratified by a sufficient number of countries in September 2016. The most important part of the Convention is Regulation D-2. One way to meet D-2 is to retrofit Ballast Water Treatment Systems (BWTS) on existing ships and their fitting on newbuildings. The market consists of the following stakeholders: shipowners, equipment manufacturers, shipyards, recognized organizations, laboratories for testing the efficacy of the BWTS and coastal countries’ administrations in charge for implementing Convention standards. In order to enable enough time to comply with the Convention, shipowners are granted maximum 5 year period, i.e. system retrofitting is connected to the first renewal of the International Oil Pollution Prevention certificate after September 2017. Some shipowners will postpone retrofitting for five years since they will renew IOPP certificates in advance, which is approved by many flag States and stated in their circular letters. More than 60 systems received flag State type approvals, but only few systems are approved by United States Maritime Administration (MARAD). That is one of the reasons why most of the shipowners are still waiting with planning and retrofitting, which leads to requests for more postponement. However, many manufacturers claim that they will be ready for increased demand for BWTS and will cope with and try to satisfy market demand by hiring additional work force, by expanding existing manufacturing facilities and maintain good cooperation with shipyards.
... It is desirable to have long period of operation between refueling outages and to match refueling with the ship planned maintenance periods, which occurs each two and a half years [13], giving flexibility and reducing downtime. To reduce downtime due unplanned maintenance, the architecture must allow detaching the entire mobile nuclear power plant within few hours. ...
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Recent studies point to a reduction of atmospheric pollution using nuclear energy for merchant ships. This work examines the development of an economically competitive nuclear power solution for merchant ship propulsion. The solution also addresses the requirements of a wider market, like islands, offshore oil platforms, and remote cities. System engineering and analysis at various product breakdown levels also propose architectural options to improve competitiveness of nuclear power in mobile nuclear power plants (MNPPs). Analyses include market research on clients and technical considerations on nuclear energy costs. The results show that an enterprise that delivers electric power to remote clients and dedicates to management of all nuclear aspects seems to be the best organizational and technical choice. Besides, ships should be of modular type and the MNPPs should be easily detachable at sea. Only container ships and remote islands demand enough power to justify the use of nuclear power. Nuclear power has high probability to be economically competitive for large container ships, however, only if public policies impose levels of risks akin to other industries.
... The cargo containment system of LNGCs is not used during operation due to exitance of LNG and its vapor in the containment system. A regular dry docking period is the best opportunity for maintenance of the LNG containment systems after inerting, warming up, and aerating of the containment system have been completed at a service shipyard [16,17]. LNGC dock specifications are documents that contain lists of severe and important ship maintenance tasks, including LNG containment maintenance orders during dry docking. ...
Article
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The high demand for liquefied natural gas (LNG) requires more LNG carriers (LNGCs) to be in operation. During transportation, there is a high risk due to the required extremely low temperatures and the explosive nature of LNG cargo. Moreover, when there is a lack of experience in operating old LNGCs, there is a serious concern regarding operational accidents. A systematic maintenance strategy, especially for LNG cargo containment systems, is crucial for maintaining safe LNG transportation at sea. The purpose of this study is to develop preventive LNG cargo containment system maintenance models by using LNGC dock specifications from LNGCs of various ages. The dock specifications from a conventional LNGC repairing dock were analyzed using natural language processing techniques in order to develop preventive maintenance models of the LNG cargo containment system. From these results, and by considering the ship’s age, it was found that for young LNGCs, the priority for repair should focus on checking routine consumable spare parts by tank inspections, whereas for older LNGCs, the focus should be on tank condition maintenance rather than on other facilities. These results are expected to be useful in the development of a maintenance strategy of preventive LNG cargo containment systems in maritime LNG transportation.
... In the overall maintenance cost, a significant part is on the dry-docking cost CDD. It has been estimated as [25]: ...
Article
Full-text available
For the natural gas transportation, several technologies can be applied, having different effectiveness and costs depending on the analysed case. The Mediterranean Sea is presenting a typical scenario where compressed natural gas (CNG) transportation is particularly attractive compared to liquefied natural gas (LNG) and pipelines, not only for stranded gas shipping but also for transportations cases where CNG is usually representing the most economically convenient solution. Approaching the design of a CNG ship is not an easy task, since the pressure vessel (PV) technology is strongly influencing the ship layout and hull form. Here an enhanced conceptual design method is adopted; taking into account the economic-financial issues together with logistics, in order to determine the best fleet composition selecting the best ships for the selected scenario. The ships composing the fleet are supposed to load/offload the natural gas on buoys; hence, dynamic positioning (DP) will also be considered as an attribute in the evaluation of alternative designs. As final outcome of the enhanced concept design process it will be possible to speed up drawing of the preliminary lines plan and general arrangement plan of the sister ships composing the fleet.
... The sediment disposal usually takes place during the regular ship's dry-dock maintenance. Examination of ships' hulls requires the sediments to be cleaned from the BW tanks, which is the procedure that takes place approximately every 30 months (Apostolidis et al. 2012). Namely, according to the International Convention for the Safety of Life at Sea (SOLAS), the vessels must complete an inspection of the hull in a dry-dock twice within a 5 years, while the period between two inspections should be no longer than 36 months. ...
Article
Full-text available
Purpose The International Maritime Organization’s (IMO) International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) was entered into force in September 2017. It deals with one of the greatest threats to coastal and marine environments around the world: aquatic invasive alien species (IAS) and harmful aquatic organisms and pathogens (HAOP). Although the control of IAS and HAOP through treatment of ballast water (BW) is appropriately dealt with in the Convention and its implementation, the problems generated by sediments are not treated in such a manner. Materials and methods There are many published technical and scientific papers, discussions and commentaries proposing the remediation of the present situation. They are discussed, and recommendations are summarized. Besides, several systems for the treatment of BW use a combination of two or three techniques, with filtration usually being the first and/or the last step. Presence of sediments in BW results in the reduced applicability of such an approach. Results and discussion The requirements for sediment management procedures are discussed along with a proposal for their implementation. In the first step, the ballast tank sediments should be freed of active biological agents for the elimination of IAS and HAOP. Instead of biological agents, we advocate the use of radiation treatment by using an electron accelerator, preferably in an on-shore installation or as a mobile, additive, sea container size units with integral power, separated for water and sediment treatment. In the second step, the concentrations of heavy metals should be determined. We recommend the use of EDXRF as an analytical method. After the determination of sediment class, the recommended disposal procedures should be followed. Conclusions Sediment management procedures should specify the disposal requirements: (i) free of active biological agents, IAS and HAOP; (ii) chemical composition, no chemical elements in a toxic range (≤ Class 3); and (iii) displacement/storage requirements, displacing sediments characterized as harmful in appropriate sediment reception facilities/landfills.
... The accumulated volume of sediments in the tanks depends on the ship's ballast management procedures and can reach a thickness of more than 30 cm [9]. In this regard, the sediments must be removed from the BW tanks and such sediment removal typically occurs during the usual dry-dock maintenance; this process takes place usually every 30 months [10]. Besides, it must be taken into consideration that appropriate systems for the treatments of BW are based on UV irradiation [11], but abundant presence of sediments in BW reduces the efficiency of these techniques that cannot eliminate all harmful aquatic organisms and pathogens present in BW. ...
... Without claiming a complete knowledge of the contributions made, over time, by various authors, on the subject of interest [1], [3], [4], [5], [7] it was found during the documentation that the studies analyzed refer, in particular, to the minimization of ship operating costs and ship maintenance costs (depending on the evolution of the maritime transport market and the evolution of fuel prices). From the documentation made, it was found that there is insufficient information regarding the analysis, modeling and forecasting of the total period of ship maintenance and the docking period in a shipyard, although there are also authors [2] concerned with this subject, including the authors of this paper [12], [13], [14], [15], [20]. ...
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The ship repair process in shipyards is a complex one and its components are usually influenced by a significant number of factors with random variability. The retention period of a ship in the shipyard for repair works present a particular interest, both for the shipyard and for the beneficiary of the repair works. In the most general way, the variables that could be the basis for the prognosis of the total period of repair works are selected from the content of the technical specification of works prepared by the owner / technical manager of the ship.. The paper highlights some independent variables that can be taken into account when estimating the period of repair work. The case studies presented in the paper refer to a portfolio of 400 tank type ships for which repair works were carried out in the Constanta Shipyard.
... Repair and maintenance operations at a shipyard are related to the process of ensuring and managing the resources necessary to carry out the works included in the technical specification. This process comprises two fundamental approaches [2], [7], [9], [29]: a) strategic: refers to the design of the complex system of maintenance / repair operations of a ship in a shipyardsetting performance requirements; establishing the volume of works; establishing the technologies of execution of the works; establishing the required number of machinery and equipment; establishing locations for machinery and equipment; establishing the necessary workforce; establishing management and control methods; b) tactics: ensures the operation of the system at the designed parameterswork planning; management of works; stock management; quality control. ...
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The repair and maintenance operations carried out within a shipyard are correlated with the process of ensuring and managing the resources necessary to carry out the works included in the technical specification. Resource planning is a complex issue that can be addressed from several points of view. Initially, the planning of activities is done taking into account only the analysis of the time parameter and the dependencies between activities imposed by the technological process. The practice of the activities carried out in a shipyard has demonstrated that an analysis of the necessary resources according to the existing availability is also necessary. There are many unforeseen situations that can affect both the time of work and resources (material, financial, human) thus complicating the process of planning activities. This paper proposes a way to analyze the resource requirements of a repair project based on available resources, through Critical Path Method diagrams. This provides a comparative view of the daily required profile for a particular resource associated with the project in respect to the daily available profile of the shipyard.
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The high demand for liquefied natural gas (LNG) requires more LNG carriers (LNGCs) to be in operation. During transportation, there is a high risk due to the required extremely low temperatures and the explosive nature of LNG cargo. Moreover, when there is a lack of experience in operating old LNGCs, there is a serious concern regarding operational accidents. A systematic maintenance strategy, especially for LNG cargo containment systems, is crucial for maintaining safe LNG transportation at sea. The purpose of this study is to develop preventive LNG cargo containment system maintenance models by using LNGC dock specifications from LNGCs of various ages. The dock specifications from a conventional LNGC repairing dock were analyzed using natural language processing techniques in order to develop preventive maintenance models of the LNG cargo containment system. From these results, and by considering the ship’s age, it was found that for young LNGCs the priority for repair should focus on checking routine consumable spare parts by tank inspections, whereas for older LNGCs the focus should be on tank condition maintenance rather than on other facilities. These results are expected to be useful in the development of a maintenance strategy of preventive LNG cargo containment systems in maritime LNG transportation.
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