Navigating Efficiency: The Role of Low-Resistance Rudders in EEXI Compliance

In the ever-evolving world of maritime regulations, the Energy Efficiency Existing Ship Index (EEXI) stands as a guiding light toward a greener, more sustainable future. Among the innovative technologies employed to meet EEXI requirements, low-resistance rudders have emerged as a key component for enhancing a vessel’s energy efficiency.

Example of vessel rudder

In this article, we will explore the significance of low-resistance rudders, the challenges they pose, the available technology on the market, and what marine engineers must consider to sail smoothly in compliance with EEXI.

The Significance of Low-Resistance Rudders

Rudders are a vital part of a ship’s steering system, but they also play a crucial role in a vessel’s hydrodynamic performance.

One of the possible ways to improve the energy efficiency of a ship is to use a low resistance rudder. A low resistance rudder is a type of rudder that reduces the water resistance and drag of the ship, which can result in significant fuel savings and lower emissions. According to some studies, low resistance rudders can reduce fuel consumption by up to 5% and carbon dioxide emissions by up to 4.5%. Moreover, low resistance rudders can also improve the maneuverability and stability of the ship, as well as reduce the noise and vibration levels.

Low-resistance rudders are designed to minimize drag and water resistance, which, in turn, reduces the energy required to steer the ship. By implementing these rudders, marine engineers can enhance a vessel’s energy efficiency and reduce its environmental impact—both central objectives of EEXI compliance.

Challenges on the Horizon

However, designing and installing a low resistance rudder on a ship is not a simple task. It requires careful consideration of various factors and challenges, such as:

  • The rudder profile: The shape and thickness of the rudder plate affect the flow of water around it and the pressure distribution on it. A streamlined rudder profile can reduce the drag and increase the lift of the rudder, which can enhance its performance and efficiency.
  • The rudder parameters: The size, aspect ratio, sweep angle, and balance ratio of the rudder influence its hydrodynamic characteristics and forces. The optimal values of these parameters depend on the ship type, size, speed, propeller design, and operating conditions.
  • The rudder type: There are different types of rudders available for ships, such as spade, flap, twisted, fishtail, Schilling, Becker, etc. Each type has its own advantages and disadvantages in terms of resistance, lift, torque, cavitation, etc. The selection of the proper type of rudder should be based on the specific requirements and constraints of each ship.
  • The number and location of rudders: The number and location of rudders affect the interaction between the rudders themselves, as well as between the rudders and the hull and propeller. The spacing between rudders should be sufficient to avoid interference and ensure effective steering. The position of the rudders should be such that they are properly oriented within the propeller’s outflow, so as to maximize their effectiveness.

Technology on the Market

To address these challenges, several advanced technologies for low-resistance rudders are available:

  • Advanced Hydrodynamic Design: Innovative rudder designs, often computer-aided, reduce hydrodynamic drag and optimize efficiency.
  • Materials and Coatings: High-quality materials and specialized coatings reduce friction and fouling, contributing to lower resistance.
  • Rudder Bulb: Some rudder designs incorporate a bulb, similar to a ship’s bulbous bow, to further reduce drag.
  • Intelligent Control Systems: Smart rudder control systems adapt to various operational conditions, optimizing rudder angles for maximum efficiency.
  • Maintenance Technology: Anti-fouling systems and regular inspection technology help keep the rudder surfaces clean and efficient.

What Marine Engineers Need to Do

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

  • Hydrodynamic Assessment: Evaluate the vessel’s hydrodynamic characteristics and operational profile to determine the most suitable low-resistance rudder design.
  • Supplier Collaboration: Work closely with reputable rudder suppliers to select the most appropriate design and technology for the vessel’s specific needs.
  • Installation Oversight: Oversee the precise installation of the low-resistance rudder, ensuring it integrates seamlessly with the existing steering system.
  • Performance Monitoring: Implement a monitoring system to track the rudder’s performance over time. Regular inspections can help detect any wear or fouling that may affect efficiency.
  • Crew Training: Ensure that the vessel’s crew is trained to operate the low-resistance rudder effectively and adapt to its performance characteristics.
  • Maintenance Regimen: Develop a proactive maintenance plan to keep the rudder surfaces clean and free from fouling, optimizing energy efficiency.

In conclusion, low-resistance rudders are more than just a compliance tool; they represent a commitment to enhancing the sustainability and energy efficiency of the maritime industry. With the right technology, engineering expertise, and diligent oversight, marine engineers can steer vessels toward a future where efficiency and environmental responsibility coexist seamlessly, all while adhering to the EEXI regulations.

Therefore, designing and installing a low resistance rudder on a ship requires a lot of planning, coordination, and supervision from vessel marine engineers. They have to select the right rudder profile, parameters, type, number, and location for their ship’s needs and budget. They have to oversee the fabrication and installation of the rudder according to the relevant regulations and standards. They have to ensure that the rudder meets the specifications and requirements for EEXI compliance. And they have to evaluate the performance and benefits of the rudder after its installation.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World, Telegram Chief Engineer’s Log Chat or Instagram and will try to answer to all your queries. You can use the feedback button as well!

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published.

Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

Source and References:

  • EEXI | Energy Efficiency Existing Ship Index – DNV
  • EEXI and CII – ship carbon intensity and rating system – IMO
  • Everything you need to know about the EEXI – SAFETY4SEA
  • Design and Evaluation of Ship Rudders | SpringerLink
  • OSK-ShipTech test a rudder bulb – OSK Design Youtube channel

Sailing Smoothly: The Role of Low-Friction Coatings in EEXI Compliance

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.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World, Telegram Chief Engineer’s Log Chat or Instagram and will try to answer to all your queries. You can use the feedback button as well!

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published.

Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

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

Navigating Green Waters: Propulsion and Engine Optimization for EEXI Compliance

The maritime industry is at the helm of significant change as it sails toward a more sustainable future. With the Energy Efficiency Existing Ship Index (EEXI) regulation coming into effect in 2024, vessel owners and operators are tasked with optimizing propulsion systems and engines to reduce greenhouse gas emissions. If you want to read more about EEXI please follow THIS LINK.

In this article, we’ll dive into the challenges, available technology, and what marine engineers need to do to navigate this sea of change successfully.

Challenges on the Horizon

Complying with the EEXI regulation presents several challenges, primarily centered around improving energy efficiency while minimizing emissions. Some of the key challenges include:

  1. Evaluating Existing Systems: Vessel owners must assess their current propulsion and engine systems to determine their energy efficiency and EEXI compliance. This often requires complex calculations and data analysis.

  2. Investment Costs: Upgrading propulsion systems and engines can be a significant investment. Owners need to balance these costs with the long-term benefits of improved efficiency and compliance.

  3. Technology Integration: Implementing new technologies and optimizing engines can be a complex process. Ensuring these systems work seamlessly with existing onboard systems is crucial.

  4. Regulatory Compliance: Meeting EEXI requirements necessitates compliance with stringent emissions standards. Staying up to date with evolving regulations is an ongoing challenge.

Technology on the Market

To address these challenges, a range of innovative technologies and solutions are emerging in the maritime sector:

  1. Fuel-Efficient Engines: Modern, fuel-efficient engines with advanced combustion technologies and improved design are becoming more widely available.

  2. Exhaust Gas Cleaning Systems: Technologies like scrubbers and selective catalytic reduction (SCR) systems help reduce emissions from engines, aligning with EEXI standards. More about this if you follow THIS LINK.

  3. Alternative Fuels: The adoption of alternative fuels such as LNG, hydrogen, and ammonia can significantly reduce greenhouse gas emissions.

  4. Energy Recovery Systems: Systems that recover and reuse waste energy from the engine, such as waste heat recovery systems, contribute to greater efficiency.

  5. Propulsion Efficiency Solutions: Upgrading propulsion systems with modern propellers and thrusters designed for efficiency can reduce fuel consumption.

    Source and Credit: MOL

    One of the most common methods to improve the attained EEXI is to limit the engine power or shaft power of the ship. This can be done by re-setting the fuel index by limiting the fuel rack using either mechanical stop or setting the control system in combination with an approved override functionality as defined in the IMO guidelines. This method is called Engine Power Limitation (EPL) or Shaft Power Limitation (ShaPoLi). To read more about this, please follow THIS LINK.

    However, this method also poses some challenges and risks for the ship operation, such as reduced maneuverability, increased fuel consumption, increased maintenance costs, and potential safety issues.

    Therefore, ship operators need to consider other measures to optimize the propulsion and engine performance of their ships, such as installing energy saving devices, using alternative fuels, or upgrading the propulsion system. Some of the available technologies on the market that can help achieve this are:

    • FuelOpt: This is a propulsion optimization system developed by Yara Marine Technologies that provides an integrated ShaPoLi feature that complies with the EEXI framework. The system enhances vessel efficiency while minimizing the impact of engine or shaft power limitations on daily operations. FuelOpt can also reduce fuel consumption and emissions by controlling the propeller pitch and engine load in real time.
    • Rotating sails: These are vertical cylinders that rotate around their axis and use the Magnus effect to create a forward thrust. They can be installed on existing ships as an auxiliary propulsion system that can reduce fuel consumption and emissions by up to 20%. Some examples of rotating sails are Flettner rotors and Norsepower rotor sails .
    • Bulbous bow: This is a protruding bulb at the bow of a ship that modifies the water flow around the hull and reduces the drag. It can improve the hydrodynamic efficiency of a ship and reduce fuel consumption and emissions by up to 15%. However, it requires careful design and optimization for different ship types and speeds.
    • Propeller fins: These are appendages attached to the propeller blades that increase the thrust and efficiency of the propeller. They can reduce fuel consumption and emissions by up to 5%. Some examples of propeller fins are Becker Mewis Ducts and Propeller Boss Cap Fins .
    • Alternative fuels: These are fuels that have lower carbon intensity than conventional marine fuels, such as liquefied natural gas (LNG), biofuels, hydrogen, ammonia, or methanol. They can reduce greenhouse gas emissions from ships by up to 100%, depending on their production and use. However, they also require new infrastructure, storage, handling, and safety measures.
    • Propulsion systems: These are systems that convert energy into propulsive force, such as diesel engines, electric motors, gas turbines, or fuel cells. They can be upgraded or replaced with more efficient or low-carbon technologies that can reduce fuel consumption and emissions. Some examples of propulsion systems are hybrid propulsion, diesel-electric propulsion, or hydrogen fuel cell propulsion .

What Marine Engineers Need to Do

Marine engineers play a pivotal role in ensuring vessels comply with EEXI regulations and optimizing propulsion and engine systems. Here’s what they should consider:

  1. Data Analysis: Conduct detailed data analysis to determine the current energy efficiency of propulsion and engine systems. This forms the foundation for improvement strategies.

  2. Collaboration: Collaborate with naval architects, designers, and technology providers to select the most suitable propulsion and engine optimization solutions.

  3. Regular Maintenance: Implement a rigorous maintenance schedule to keep engines and propulsion systems in optimal working condition, reducing energy wastage.

  4. Training: Stay up to date with the latest technologies and best practices through continuous education and training programs.

  5. Monitoring and Reporting: Implement systems for real-time monitoring of engine and propulsion system performance. Regularly report on energy efficiency improvements and emissions reductions.

  6. Documentation: Maintain comprehensive records of all upgrades, modifications, and maintenance activities related to propulsion and engines for compliance verification.

The EEXI regulation is expected to have a significant impact on the shipping industry in 2024 and beyond. As the maritime industry charts a course towards greater sustainability, marine engineers are the navigators guiding vessels through these uncharted waters. By leveraging the available technology and adhering to best practices, marine engineers can help vessel owners and operators meet the challenges of EEXI compliance while contributing to a cleaner, greener future for the maritime world.

What you need to know about Energy Efficiency Existing Ship Index (EEXI)

In June of 2021, the IMO Marine Environmental Protection Committee (MEPC) held its 76th meeting, where they adopted resolution MEPC.328(76) containing amendments to MARPOL Annex VI concerning mandatory goal-based technical and operational measures to reduce carbon intensity of international shipping. Developed under the framework of the Initial IMO Strategy on Reduction of GHG Emissions from Ships agreed in 2018, these technical and operational amendments require ships to improve their energy efficiency in the short term and thereby reduce their greenhouse gas emissions.

From 1 January 2023 it is mandatory for all ships to calculate their attained Energy Efficiency Existing Ship Index (EEXI), to measure their energy efficiency and to initiate the collection of data for the reporting of their annual operational carbon intensity indicator (CII) and CII rating. The attained EEXI shall be calculated for each ship and for each ship which has undergone a major conversion.

The required EEXI value is determined by the ship type, the ship’s capacity and principle of propulsion and is the maximum acceptable attained EEXI value.

The amendments to MARPOL Annex VI are in force from 1 November 2022. The requirements for EEXI and CII certification came into effect on 1 January 2023. This means that the first annual reporting will be completed in 2023, with initial ratings given in 2024.

Vessels impacted by EEXI must demonstrate compliance by their next survey – annual, intermediate or renewal – for the International Air Pollution Prevention Certificate (IAPPC), or the initial survey before the ship enters service for the International Energy Efficiency Certificate (IEEC) to be issued, whichever is the first on or after 1 January 2023.

A ship’s attained EEXI indicates its energy efficiency compared to a baseline. Ships attained EEXI will then be compared to a required Energy Efficiency Existing Ship Index based on an applicable reduction factor expressed as a percentage relative to the Energy Efficiency Design Index (EEDI) baseline. It must be calculated for ships of 400 gt and above, in accordance with the different values set for ship types and size categories. The calculated attained EEXI value for each individual ship must be below the required EEXI, to ensure the ship meets a minimum energy efficiency standard.

The CII figures out the yearly reduction factor that is needed to make sure that a ship’s operational carbon intensity keeps getting better while staying within a certain rating level. The annual operational CII that was actually reached must be written down and checked against the minimum annual operational CII. This lets us figure out the operational carbon intensity grade.

The carbon intensity of a ship will be graded A, B, C, D, or E, with A being the highest. The rating indicates a performance level of major superior, minor superior, moderate, minor inferior, or inferior. The performance level will be documented in a “Statement of Compliance” that will be expanded upon in the ship’s Ship Energy Efficiency Management Plan (SEEMP).

A ship rated D for three consecutive years, or E for one year,  will have to submit a corrective action plan to show how the required index of C or above will be achieved. Administrations, port authorities and other stakeholders as appropriate, are encouraged to provide incentives to ships rated as A or B.  A ship can run on a low-carbon fuel clearly to get a higher rating than one running on fossil fuel, but there are many things a ship can do to improve its rating, for instance through measures, such as: hull cleaning to reduce drag, speed and routing optimization, installation of solar/wind auxiliary power for accommodation services, installing main engine power limiters etc.

The easiest way to get the energy efficiency index down is to reduce engine power, as vessels’ fuel consumption and emissions, respectively, increase as speed increases. The propulsion power, thus CO2 emissions, is approximately proportional to the cube of the speed. This means that reducing speed by 20% can drop the emitted CO2 by 50%. Slow steaming, therefore, is a more carbon-efficient way to transport goods. The engine power limitation systems can be bypassed, but only if required for the safe operation of the ship, for example, in harsh weather conditions.

Example of mechanical EPL developed by MAN

The Engine Power Limiter (EPL) must be overideable and will limit engine power by restricting the fuel index to a calculated set value. This restricts the total amount of fuel that can be injected into the engine and thereby limiting the power the engine can produce. For correct installation, the EPL must limit the fuel index to match the engine power for MCRlim.

The Engine Power Limitation (EPL) as such does not alter NOx critical settings or components of the engine.

The calculation of the EEXI follows the calculation of the well-known EEDI. It is based on the 2018 calculation guideline of the EEDI, with some adaptations for existing vessels. In principle, the EEXI describes the CO2 emissions per cargo ton and mile. It determines the standardized CO2 emissions related to installed engine power, transport capacity and ship speed. The EEXI is a design index, not an operational index. No measured values of past years are relevant and no on-board measurements are required; the index only refers to the design of the ship.

The emissions are calculated based on the installed power of the main engine, the corresponding specific fuel oil consumption of the main engine and of auxiliary engines (taken from the engine test bed), and a conversion factor between the fuel and the corresponding CO2 mass. The transport work is determined by capacity, which is usually the deadweight of a ship and the ship speed related to the installed power.

The calculation does not consider the maximum engine power, but for most ship types it is 75% of MCR or 83% of MCRlim (in case of an installed overideable power limitation). Specific fuel oil consumption of the main engine and ship speed are regarded for this specific power.

In conclusion, the EEXI is applied to almost all ocean going cargo and passenger ships above 400 gross tonnage. For different ship types, proper adjustments of the formula, through correction factors have been introduced to allow a suitable comparison. Several correction factors are defined to correct the installed power, such as for ice-classed ships, as well as to correct the capacity, for instance to consider structural enhancement. From a technical perspective, all ship owners and shipbuilding stakeholders must consider and assess how they will support compliance with EEXI. Depending on the vessel age and prospects, some owners and operators may even be scrapping vessels earlier than envisioned.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World and will try to answer to all your queries.

If you like my posts, please don’t forget to press Like and Share. You can also Subscribe to this blog and you will be informed every time when a new article is published. Also you can buy me a coffee by donating to this website, so I will have the fuel I need to keep producing great content! Thank you!

Source and Bibliography:

Ship Energy Efficiency

The overall energy efficiency of a vessel is determined by the choices made throughout its lifecycle, from the planning and new build phases to the final recycling phase, and is measured by the total amount of energy consumed in relation to a specific output, the total energy or fuel consumed per nautical mile.

Improving energy efficiency is one of the strategic plans of most shipping companies because the benefits include: lower fuel costs, which have risen significantly in recent years and are expected to rise further in the future, environmental protection, and compliance with current and future regulations.

The IMO has introduced mandatory requirements to encourage energy savings and reduce greenhouse emissions, which are currently centered on the SEEMP – the Ship Energy Efficiency Management Plan. The SEEMP’s goal is to create a mechanism for a company and a ship to improve the energy efficiency of ship operations.
The SEEMP aims to increase a ship’s energy efficiency in four steps: planning, implementation, monitoring, and self-evaluation and improvement.
These components are essential in the continuous cycle of improving ship energy management. The pursuit of energy efficiency requires more responsibility than the ship owner and operator can provide.
The list of all the parties involved in the efficiency of a single voyage is lengthy. Designers, shipyards, and engine manufacturers for optimal ship design, charterers, ports, and vessel traffic management services, and, of course, the crew for the specific voyage are obvious parties. All parties involved should consider incorporating efficiency measures into their operations, both individually and collectively.

Everyone onboard is responsible for using the least amount of energy necessary to do their job effectively and safely, because increasing energy efficiency benefits the ship, the operator, and the environment.

Key development areas should be identified and considered early in the business planning process. Comparing the performance benefits and lifetime costs of different investment opportunities can be a difficult task, and decision makers must find technically and economically optimal improvements.

It is critical to understand that a well-designed new ship can save up to 50% in operational costs when compared to an older ship. Up to 30% of this can be saved through fuel savings, as fuel consumption accounts for up to 50% of the total cost of operating a commercial cargo vessel. The easiest to assess and monitor is fuel usage reduction, as long-term forecasting of fuel price fluctuations is difficult.
Fuel prices were relatively low in the 1960s and 1970s. Many ships were built with little regard for energy efficiency. Newer vessels are designed to be more fuel efficient. The value of fuel efficiency will continue to rise and initial investments are required for energy efficiency. The profitability of this depends on a variety of factors, including the type of cargo being transported, interest rates, fuel prices, and the expected lifetime of the ship, among others.

Generally speaking, a ship’s life expectancy on regular routes is expected to be greater than that of a ship on irregular chartering in unstable financial conditions. The time it will take to recoup the initial investment should be considered when calculating the investment benefit. Short-term measures could save up to 10% of fuel consumption. Long-term measures should reduce it by at least 20% to 30%.

Ship design is the art of selecting a vessel configuration that corresponds to the mission, intended operational profile and route, as well as the operator’s performance requirements. This necessitates a thorough understanding of the vessel type, as well as new technologies and how they integrate with the vessel.
The first step toward improving energy performance is to recognize that the ship’s current performance is heavily influenced by the ship’s design. The hull shape and bow design, propeller and propulsion system, ship automation and crewing, heat recycling, and power generation are all important design factors in a vessel’s energy efficiency.
The above are normally chosen during the ship’s design and construction stages, but new developments in maritime design have made it possible for retrofitting or later design to deliver greater fuel economy.
The shape of the hull determines the ship’s water resistance and thus its fuel consumption.

Example of long slim hull design

A long, slim ship will provide less resistance than a short, beamy ship. Fuel consumption is also affected by the shape of the bow and stern.
The benefit of the bulbous bow has been well known for many years. Later research shows that this is also true for smaller vessels. Fuel savings of 25 to 50% can be obtained by increasing the length/beam ratio from 4.5 to 6.5. The optimal length/beam ratio is a trade-off between cargo capacity, harbor dimensions, and fuel consumption.

Example of bulbous bow replacement for efficiency purpose

Experience has shown that increasing the total length of the ship has little effect on the energy required to maintain the same speed as before.

Approximately half of the energy consumed by the ship’s main engine is wasted, primarily through cooling water and exhaust gases.
Heat recovery devices reduce energy losses by passing the hot exhaust gas through a heat exchanger and converting it to steam. Steam is then used to pre-heat fuel, turbo generators, and other heating devices. The benefits of installing such devices vary depending on the type of equipment that needs to be installed. However, in most cases, the amortizing time, or time to recover costs, will be around two years.


Exhaust gas recovery system example

A fuel gauge and a speed log are the bare minimum for better fuel economy. Onboard computers calculate fuel consumption in relation to the distance traveled and the vessel’s speed. Instruments used correctly can reduce fuel consumption by nearly 10%.

Example of mass flowmeter installed onboard vessel

Many ships have relatively high propeller speeds, ranging from 300 to 400 rpm. Cutting the speed in half could reduce fuel consumption by up to 25%. Larger propellers necessitate more space. This is limited by the shape of the stern and the ship’s draught. Longening the propeller shaft and the overhanging stern is one option. A new reduction gear box should be installed in addition to the new propeller. Ships with slow speeds and high propeller loads will benefit from the use of a nozzle around the propeller. However, most cargo ships traveling long distances will benefit little, if at all.

Example of high efficiency propeller

Diesel generators, turbo generators, and main shaft generators can all generate electricity. The type of engine and the ship’s management profile will determine which type is the most energy efficient. Shaft generators should be considered for fast and continuous-running engines.

Example of shaft generator

Small changes in operating conditions can result in significant changes in energy consumption, making it critical to continuously optimize operations throughout the ship’s lifecycle.

Optimal navigation can save up to 25% of fuel consumption, resulting in significant savings. Economical routing, time spent in port and at sea, speed optimization, continuous load output, optimal propeller pitch, engine efficiency, total efficiency, optimum draught and stability, reporting and computerized logging are all potential areas for efficiency improvement in ship navigation.
With such a diverse set of variables to consider, high performance in vessel navigation is possible if interrelationships are well understood and utilized.
The careful planning and execution of voyages can result in optimal routing and increased efficiency. Thorough voyage planning takes time, but there are a variety of software tools available for planning purposes. Routing is the calculation of the most efficient path. Land masses, soundings, prevailing currents, prevailing winds, and tide effects are all factors to consider. Once the route is established, it is the navigator’s responsibility to stick to it unless unusual weather conditions dictate otherwise. In general, excessive rudder use is not recommended because it slows down the vessel unnecessarily. In most cases, an autopilot will keep you on course better than manual steering.

The most significant energy savings can be achieved by reducing the ship’s speed, but unfortunately will also reduce its transportation capacity. As the ship’s speed increases so does the fuel consumption and even a small speed increase results in large increase in fuel consumption.

Based on experience operation at constant power can be more efficient than continuously adjusting the speed through engine rpm, but if the arrival time is the priority and the weather uncertain it is wise to allow for a sufficient time margin.

Harbour maneuvers should be done with progressive and moderate accelerations if the conditions allow for it, as any hard maneuver is a strain on the engine and a waste of fuel.

Some ships have a tendency to bury of lift their bow and the speed should take this into account, as in some ships it is possible to asses and adjust for optimal trim condition which will improve fuel efficiency continuously throughout the voyage.

Ballast should be adjusted taking into consideration the optimum trim and steering conditions and optimum ballast conditions should be achieved through good cargo planning. Ballast conditions have a significant impact on steering conditions and autopilot settings and it needs to be noted that less ballast water does not necessarily mean the highest efficiency.

If you have any questions regarding above, please feel free to use our existing forum Seafarer’s World and will try to answer to all your queries.

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