Introduction
The shipping industry has become vital for facilitating trade, defense, and the overall global economy. Maritime shipping is among the most critical components of the international economy, accounting for around 90% of trade conducted worldwide (Balcombe et al., 2019). However, there has been increasing pressure on the industry to reduce its adverse environmental impact, especially in terms of CO2 emissions, despite the fact that sea transport releases less carbon dioxide compared to other vehicles (Swain et al., 2022). However, the maritime sector is considered a great contributor to global environmental impacts due to the large scale of operations and the growth of demand for them.
Therefore, hull management is an essential part of ship operations that can include various measures aimed at reducing the unwanted environmental impact. Such measures as ship hull grooming, for example, have been developed as proactive management methods aimed at addressing the fouling control coating, ensuring that there is no excessive discharge of harmful substances into the waters and air. This paper seeks to discuss how improved efforts of hull management could lead to decarbonizing shipping by making it more energy efficient, taking into account the available measures and future methods that could be implemented to decrease the carbon footprint.
Measures to Enhance Ship Efficiency
Effective technical management of ships ensures that the equipment on ships and power systems are in a good operational condition that could enable significant energy savings. Hull management for efficiency is concerned with the following steps:
- Preventing hull overgrowing and corrosion with antifouling coating systems;
- Cleaning the propeller blades’ surfaces;
- Establishing an effective management system consisting of regular technical and maintenance reports (Waliszyn, Adamkiewicz, & Yafasov, 2018).
Preventing hull overgrowth is an important aspect of hull management as marine growth attaching to ships can cause problems in functioning. Specifically, different forms of algae, seaweed, and slime can profusely overgrow on ship hulls. At the same time, such animals as mussels and barnacles will adhere to the underwater surface of the ship and reproduce significantly (Xaxx, 2019). The process of animal and plant life growing on hulls is referred to as “fouling,” which has an adverse impact on the efficiency and profitability of the shipping industry. Fouling has shown to result in reduced ship speed, increased consumption of fuel, as well as “increased emission of polluting exhaust gases, sulfur oxides, nitrogen oxides, and greenhouse gases, including CO2” (Kutz, 2018, p. 89). Thus, both underwater hull and propeller fouling leads to decreased vessel performance and its energy efficiency. Once the propeller and the hull are designed and manufactured, it is imperative to maintain their surfaces contained underwater, smooth, and fouling-free for ship operators to increase vessel performance.
Special paints and antifouling coating systems are used to prevent the underwater hull from fouling attachment. Notably, to maintain environmental sustainability, when antifouling coating systems are used, they must align with the IMO International Convention on the Control of Harmful Anti-Fouling Systems on Ships (Kutz, 2018). The restrictions are especially concerned with banning the use of tributyltin biocide, which used to be contained in the coating. In addition, the application and reapplication of the tri-butyl tin organotin compound is restricted despite its acting as a biocide in antifouling systems.
Paying particular attention to the efforts of control and management of fouling is necessary because of the potential risks of transferring harmful substances into the aquatic ecosystems. However, the prevention of invasive aquatic species remains a challenge, which is why a consistent approach to biofouling management is needed. Consistent control and maintenance are expected to improve the hydrodynamic performance of ships, which can play a defining role in enhancing energy efficiency and lowering air emissions from ships. The concept of effective hull management linked to fouling prevention has been recognized by the IMO Resolution regarding the “Guidance for the development of a ship energy efficiency management plan (SEEMP)” (Kutz, 2018). This suggests that implementing the measures of consistent hull management go hand-in-hand with ships’ decarbonization.
In addition to using antifouling coating systems, consistent cleaning of the hull and propeller are well-established management practices aimed at boosting the performance of ships. Regular cleaning practices will reduce fouling buildup and prevent the increased resistance of vessels and their fuel consumption. Notably, the current cleaning standards and processes have informally changed. Still, there is an increased need for establishing formal standards for ensuring that cleaning is carried out within a set of universal specifications. Moreover, cleaning products for hull and propeller maintenance must be disposed of in an environmentally sustainable manner.
It is the task of vessel operators to make decisions on whether a complete and complicated cleaning is required or a scheduled propeller cleaning would be enough. As noted by Kalyanaraman (2019), a case study by Propulsion Dynamics Inc. assessed the fuel cost benefits of cleanings and suggested an optimum strategy for hull management. Thus, it is necessary to clean propellers more often because, even though the surface area is smaller than the hull, but the effect of a rough and unconditioned propeller on fuel consumption can be significant (Kalyanaraman, 2019). The roughness of a propeller is a result of the damage to the metal, calcium deposits, any mechanical damage, as well as both soft and hard marine fouling.
In addition to marine fouling, propellers have the tendency to develop a hard and rough layer of calcareous chalk, which is the result of a by-product of the cathodic protection system. It was found that ships tend to have sacrificial zinc or impressed current anodes that generate electrons that flow to the paint-damaged areas on the hull and propeller to prevent corrosion. However, this leads the areas of bare metal to become cathodic; in doing so, they reduce the water and oxygen ions reacting with magnesium, calcium, and carbon dioxide to cause the formation of calcium and magnesium carbonates (Daehne et al., 2017). The deposits of chalk add protection to the metal surfaces of the propeller; at the same time, they lead to significant roughening that reduces the efficiency of a shit. Moreover, if a propeller becomes fairly rough, it must be restored to its initial state, or close to it, which will require grinding away on the material itself. Therefore, to prevent calcium buildup from becoming problematic to manage, periodic cleaning of the propeller and controlling its condition can remove biofouling, prevent the impact of cavitation damage, and remove the deposits of calcium.
The optimization of the hull condition, including the good state of the propellers, can be achieved by establishing an effective management system consisting of regular technical and maintenance reports. While it has been established that hull and propeller maintenance is essential for energy efficiency, having a management system in place can significantly simplify the processes. The system can be broken down into such sections as recording, supervision, and deadline. The recording aspect may include divers’ reports on the state of the hull and propellers, the use of the MARORKA system, as well as monthly technical reports completed by the chief mechanic. The MARORKA system is essential to mention because it can facilitate effective hull management through data-driven applications aimed at reducing fuel consumption, cutting emissions, and increasing ship performance (MARORKA, 2022). The more data is being collected on hull conditions, the more effective the efforts of maintenance and management will be.
At the stage of supervision, the specialists responsible for hull management will evaluate its condition on the basis of the reports that have been gathered. The fleet supervision center will exchange information with technical departments to assess hull condition and determine the appropriate management efforts. Finally, the deadline aspect of the system of hull management entails continuous supervision and ongoing improvements of the hull condition to prevent hedging and other forms of buildup that hinder fleet performance and efficiency.
Measures for Monitoring the Effectiveness of Hull Management
As mentioned in the previous section, an effective system of hull condition monitoring is a crucial part of effective management. It is notable that the scope of the system, the nature of its display and use, and the aims of data processing depend on the needs and expectations of vessels’ owners as well as the recommendations of system suppliers (ABS, 2020). Overall, the process of monitoring the effectiveness of hull management efforts includes data measurement, the collection and conditioning of data, processing and evaluation, as well as presentation and storage of data. Hull monitoring systems are established for acquiring, displaying, and/or recording information that is later used for decision-making to improve operational efficiency, sustainability, and safety.
To achieve the effectiveness and efficiency of ships, measures should take into account four key performance indicators. They have been outlined in the ISO 19030 standard that has isolated hull performance based on factors such as engine efficiency, propeller speed, waves, and wind (Shaw & Lin, 2021). All these indicators are essential for operators who strive to achieve operational improvement, while some include dry-docking performance as a critical indicator (Shaw & Lin, 2021). This determines the effectiveness of the work being done, including taking measurements following present out-docking.
In a Jotun case study, the ISO 19030 framework was applied to hull management of an LNG carrier (a tank ship that usually transports liquefied natural gas) over the course of eight years. The analysis of operational parameters embedded into the monitoring system revealed that a high-quality application of the most advanced premium coating increases ship performance by 5% (Jotun, 2019). Therefore, the monitoring system that considers ISO 19030 principles must monitor the quality of hull coating application because of its significant effects.
In addition to measuring the quality of hull coating application, the case study implied measuring the maintenance trigger and maintenance effect, which fall under ISO 19030. It was revealed that a drop in performance prompted a propeller and hull inspection, and after cleaning, performance improved significantly. In the era of big data analytics, it has become easier to track relevant hull maintenance data in real-time using sensors and various software products for data analysis. The combination of the latest technologies enables ship operators to better measure the performance of the hull and propeller through high-frequency data, dataloggers, torque meters, and high-quality cabling. Initially, it is recommended for ship operators to begin using the ISO 190 standard for enhancing the effectiveness of monitoring hull management efforts by adding newer technologies and methods to improve data measurement.
Robotics in Future Hull Management
Technologies for hull management have been developing hand-in-hand with the latest advancements in hardware and equipment. With the rising consciousness for green shipping and the link between hull fouling and loss of efficiency, considerations for tools intended for hull cleaning have led to the emergence of hull cleaning robots. The latest example is the innovative hull cleaning robot named HullBUG, developed by SeaRobotics and funded by the US Navy Office of Naval Research (Jotun, 2019). The underwater hull grooming tool is a relatively small autonomous robot that weighs in the range of 66 and 88 lbs, which uses four wheels and attaches itself to the ship’s underside (Jotun, 2019). The negative pressure device installed into the robot creates a vortex between the hull and the HullBUG. The robot is used to crawl on the hull surface and perform regular grooming, which entails the light cleaning of fouling films that begin forming. The robot sensors enable the tool to avoid obstacles, path cleaning, and navigation capabilities. The BUG has a fluorometer that allows for detecting the biofilm and then using a rotary brush and water-jects to clean off the fouling film.
It has been estimated by the robot’s developers that when it is put into practice, it can lead to a 5% fuel efficiency improvement because of proactive grooming, which can translate into annual $15 billion savings for the entire shipping industry around the world (Jotun, 2019). Besides, it is expected that the regular use of the BUG across the shipping industry can lead to the reduction of one billion tons of greenhouse gases emissions of the fleet (Jotun, 2019). The advancement in robots-hull cleaners technologies in the future is expected to improve the effectiveness of hull management efforts, especially when it comes to avoiding fouling.
Besides robot cleaners, robot ship inspectors were designed and manufactured. The use of robotics for ship inspections can be helpful because of the potential to cut the need for human resources to perform routine tasks. The robots can assess the ships for the presence of any cracks, corrosion, and other forms of wear to ensure that they comply with the increasing safety standards, which is often a time-consuming job. Besides, inspectors that usually perform this task often have to risk their safety because of having to climb onto different parts of the vessel to look at them up close (Kumar, 2019). With the help of robotic technologies, it is possible to save time and money for ship owners while also improving the accuracy and the quality of the inspections.
A prototype of the inspection robot was developed by the ETH Zürich and ZHdK team in collaboration with Alstom Inspection Robotics – an affordable and lightweight Ship Inspecting Robot. The prototype has shown the capacity to carry out visual inspections of ballast tanks’ condition, as well as other hard-to-reach parts (Kumar, 2019). The four magnetic wheels and the overlapping wheelbase allow the robot to navigate the unusual obstacles; it is controlled with the help of a wireless transmitter that transfers live video footage for inspectors to see.
It is notable that the numbers and the range of robotic tools aimed at hull management and overall ship maintenance are expanding each year. Marine robotics researchers and developers have been looking into various technologies for improving the inspection process of large ocean-going vessels and facilitating enhanced and efficient hull management. The advancements in the sphere of multi-sensor robot systems for inspection and maintenance offers ample opportunities for product development, the investment in which can significantly improve ships’ efficiency and facilitate ongoing decarbonization. Notably, in addition to the mentioned types of ship robotics, such technologies as anti-piracy robots and even full-fledged robotic vessels have been developing.
Commentary on References Reliability
The topic of hull management and effective maintenance is a relatively skewed one due, and there is limited up-to-date research on the issue. The articles allocated from scholarly and peer-reviewed journals such as New Trends in Production Engineering, Energy Conversion and Management, Integrated Environmental Assessment and Management, Frontiers in Marine Science, and others can be given a high reliability ranking. The peer-reviewed articles and chapters from a book referenced in the paper synthesize abundant evidence from various industry journals, conferences, and primary research reports. The quality of the articles published on online platforms is of lower quality; however, the information is up-to-date and provides commentary on the latest trends and technologies, which may not have been explored in peer-reviewed literature just yet. Overall, reviewing the available literature, it has become clear that more research on the topic of hull management is needed because there are gaps between studies published in early 2000 and fairly recent research.
Conclusion
To conclude, effective hull management and the monitoring of a vessel’s condition have been shown to be critical components of ship performance optimization as well as cost-effectiveness. Since the shipping industry is transforming and will continue changing to meet the latest trends and tendencies, ship owners and operators are expected to provide innovative and efficient services. Consistent hull management, which includes monitoring, the identification of risks, and regular cleaning, has been shown to enhance the efficiency of vessels as they use less fuel and emit less carbon dioxide when there is no additional resistance in the form of fouling, corrosion, or calcium buildup. Establishing a monitoring system that assesses the physical condition of the hull is essential for relevant data tracking, the identification of the need for maintenance, and reporting for storing data gathered throughout more extended time periods.
The research revealed that technological advancement had facilitated the development of robotic tools used in the maritime industry for hull management and ship condition inspections. Robots have shown to be effective tools for reducing the time and human resources necessary to implement cleaning and other maintenance tasks, including inspections. It has been forecasted that the use of hull cleaning robots could lead to significant cost savings for the global shipping industry and its decarbonization in the long-run. Further research on hull management and increased efficiency is needed due to the indicated gap in the available literature that has been allocated for this paper.
References
ABS. (2020). Guide for hull condition monitoring system. Web.
Balcombe, P., Brierley, J., Lewis, C., & Skatvedt, L. (2019). How to decarbonise international shipping: Options for fuels, technologies and policies. Energy Conversion and Management, 182, 72-88.
Daehne, D., Fürle, C., Thomsen, A., Watermann, B., & Feibicke, M. (2017). Antifouling biocides in German marinas: Exposure assessment and calculation of national consumption and emission. Integrated Environmental Assessment and Management, 13(5), 892-905. Web.
Jotun. (2019). Performance monitoring critical to optimising vessel performance – and saving money. Web.
Kalyanaraman, M. (2019). How to achieve a ‘clean’ fuel saving of US$2M between dry dockings. Web.
Kumar, S. (2019). 5 innovative robotic technologies for the maritime industry. Web.
Kutz, M. (2018). Handbook of environmental degradation of materials (3rd ed.). Elsevier.
MARORKA. (2022). Web.
Shaw, H-J., & Lin, C-K. (2021). Marine big data analysis of ships for the energy efficiency changes of the hull and maintenance evaluation based on the ISO 19030 standard. Ocean Engineering, 232, 108953. Web.
Swain, G., Erdogan, C., Foy, L., Gardner, H., Harper, M., Hearin, J., … Wassick, A. (2022). Proactive in-water ship hull grooming as a method to reduce the environmental footprint of ships. Frontiers in Marine Science, Web.
Waliszyn, A., Adamkiewicz, A., & Yafasov, A. (2018). Overview of the ship efficiency management plan for a seafaring model ship based on the IMO MEPC 231 (65) resolution. New Trends in Production Engineering, 1(1), 631-637.
Xaxx, J. (2019). Types of marine growth. Web.