In the maritime world’s ongoing quest for sustainability, the Energy Efficiency Existing Ship Index (EEXI) regulation has become a guiding star. Among the technologies and strategies used to meet EEXI requirements, low-friction coatings stand out as a promising tool for enhancing energy efficiency. In this article, we’ll dive into the significance of low-friction coatings, the challenges they pose, the available technology on the market, and what marine engineers need to know to navigate these waters successfully.

The Power of Low-Friction Coatings

Low-friction coatings, often referred to as hull coatings, are specially designed to reduce the drag and resistance that vessels encounter as they move through the water.

Low resistance coating applied to the vessel hull during dry docking

Low friction coatings are types of industrial coatings that reduce friction, wear, and energy losses between two contacting surfaces. They have different properties and applications depending on the materials used, such as PTFE, molybdenum disulfide, tungsten disulfide, nickel teflon, and diamond-like carbon. They can improve the efficiency and performance of various components and machines in different operating environments, such as heat, chemicals, or clean room conditions.

By applying these coatings to a ship’s hull, marine engineers can enhance its hydrodynamic performance, thus increasing energy efficiency and reducing fuel consumption by helping reduce the drag and resistance of a ship in water—a pivotal goal of EEXI compliance.

According to some studies, low friction coatings can reduce fuel consumption by up to 10% and carbon dioxide emissions by up to 9%. Moreover, low friction coatings can also protect the hull and propeller from corrosion, fouling, and abrasion, which can extend their service life and reduce maintenance costs.

Challenges on the Horizon

However, applying low friction coatings on a ship is not a simple task. It requires careful selection of the coating material, method, and provider, as well as proper preparation of the surface and quality control of the coating process. Some of the challenges and considerations involved are:

• Compatibility: Selecting the right coating and ensuring it’s compatible with the vessel’s hull material can be a complex process. The coating material should be compatible with the substrate material and the operating conditions of the ship. For example, some coatings may not adhere well to certain metals or plastics, or may degrade under high temperatures or pressures.
• Application: The application of these coatings must be precise to achieve optimal results. Incorrect application can lead to performance issues and cost inefficiencies. The coating method should be suitable for the geometry and size of the surface to be coated. For example, some methods may require special equipment or facilities, or may not be able to coat complex shapes or large areas.

Low friction coating applied on the whole large surface of the hull

Moreover, the coating provider should have sufficient experience and expertise in applying low friction coatings on ships. For example, some providers may not have adequate certification or quality assurance systems, or may not follow the best practices or standards for coating application.

The surface preparation should ensure that the surface is clean, dry, smooth, and free of defects before applying the coating. For example, some surfaces may require sandblasting, degreasing, priming, or masking to achieve optimal adhesion and performance of the coating.

The quality control should monitor and verify that the coating process is done correctly and that the coating meets the specifications and requirements. For example, some quality control measures may include visual inspection, thickness measurement, adhesion test, hardness test, or friction test.

• Maintenance: Maintaining the coating’s effectiveness over time requires proper care and periodic inspections.
• Environmental Considerations: Some coating materials may have environmental implications, so it’s crucial to balance the benefits of reduced fuel consumption with potential environmental impacts.

Technology on the Market

To address these challenges, several types of low-friction coatings are available:

• Silicone-Based Coatings: These coatings offer excellent hydrophobic properties, reducing friction with the water and improving fuel efficiency.
• Fluoropolymer-Based Coatings: Known for their durability and low friction, these coatings provide long-term benefits.
• Biocide-Free Coatings: To address environmental concerns, biocide-free coatings are emerging as a sustainable option.
• Self-Polishing Coatings: These coatings gradually release a layer of bioactive material, maintaining low friction throughout the vessel’s operation.
• Hybrid Coatings: Combining different technologies, hybrid coatings aim to provide an optimal balance of performance and environmental friendliness.

What Marine Engineers Need to Do

Marine engineers play a pivotal role in the successful implementation and maintenance of low-friction coatings:

• Material Assessment: Evaluate the vessel’s hull material and operational conditions to determine the most suitable type of low-friction coating.
• Supplier Selection: Collaborate with reputable coating suppliers to select the appropriate product, ensuring compatibility and environmental considerations are addressed.
• Application Oversight: Oversee the precise application of the coating, ensuring it adheres to manufacturer guidelines for maximum effectiveness.
• Performance Monitoring: Implement a monitoring system to track the coating’s performance over time. Regular inspections can help detect wear and tear, ensuring ongoing compliance with EEXI standards.
• Environmental Responsibility: Consider the environmental impact of the chosen coating and implement measures to mitigate any potential harm.
• Documentation: Maintain detailed records of the coating application, performance assessments, and any maintenance activities for compliance verification.

In conclusion, applying low friction coatings on a ship requires a lot of planning, coordination, and supervision from vessel marine engineers. They have to select the right coating material, method, and provider for their ship’s needs and budget. They have to oversee the surface preparation and quality control of the coating process. They have to ensure that the coating is applied in accordance with the relevant regulations and standards. And they have to evaluate the performance and benefits of the coating after its application.

Low-friction coatings are not just a means to EEXI compliance; they represent a commitment to reducing the environmental footprint of the maritime industry. Marine engineers, equipped with the right technology and knowledge, can help vessels sail more efficiently and sustainably. With careful planning, selection, and oversight, low-friction coatings can be a powerful tool in navigating the seas of energy efficiency and environmental responsibility.

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Source and Bibliography:

• EEXI | Energy Efficiency Existing Ship Index – DNV

• EEXI and CII – ship carbon intensity and rating system – IMO

• An Introduction To Low Friction Coatings – Ws2coating:

• Things About Low Friction Coatings That You Never Knew