Gu Yajuan, CCS Shanghai Rules & Research Institute  

In the context of the global shipping industry’s accelerated transition towards green and low-carbon operations, China Classification Society (CCS) has continuously increased its research and development efforts in rules and standards for wind-assisted ship propulsion technology. In 2020 and 2023, CCS successively released the “Guidelines for Evaluation and Inspection of Marine Hard Wing Sails” and the “Guidelines for Survey of Marine Wind-Rotor Assisted Propulsion System”. These guidelines provide comprehensive and advanced technical rules and survey standards for the application of marine wind-assisted propulsion technology, offering strong technical support for the global shipping industry’s green transformation.

Guidelines for Evaluation and Inspection of Marine Hard Wing Sails

The “Guidelines for Evaluation and Inspection of Marine Hard Wing Sails” (hereinafter referred to as the “Guidelines”) released by CCS not only provides a technical basis for ship design and construction but also ensures the safety and reliability of rigid wing sail installations. The release of these “Guidelines” marks CCS’s leading position in the field of ship energy efficiency technology and offers significant support for the global shipping industry’s green transition.

1.Technical Requirements

The “Guidelines” cover the technical requirements for the design, manufacturing, installation, survey, and operation of rigid wing sails, ensuring their safe application on ships. The cutting-edge technical specifications of the “Guidelines” is mainly reflected in the following four aspects:

(1) Comprehensive Risk Assessment and Application of Safety Concepts. The “Guidelines” require a comprehensive risk assessment of rigid wing sails to ensure that they do not negatively impact the safety of the ship during design, manufacturing, and operation. Through Failure Modes and Effects Analysis (FMEA), the “Guidelines” clarify the safety requirements of rigid wing sails under different operating conditions, ensuring their stable operation under extreme conditions.

(2) Stringent Strength and Fatigue Assessment Requirements. The structural strength of rigid wing sails directly affects the safety of the ship. The “Guidelines” require detailed strength calculations and fatigue analyses for key components of rigid wing sails, ensuring their safety under various wind and wave conditions. Through finite element analysis and other methods, the “Guidelines” provide a scientific basis for the structural design of rigid wing sails, ensuring their ability to withstand various loads during ship operations.

(3) Systematic Control and Monitoring Alarm Requirements. The “Guidelines” set strict requirements for the control systems, monitoring alarm systems, and safety systems of rigid wing sails, ensuring that they can monitor their operating status in real-time and take safety measures promptly in case of failure. Through intelligent control systems, rigid wing sails can automatically adjust the sail angle according to wind direction and speed, maximizing the utilization of wind energy and improving the energy efficiency of the ship.

(4) Detailed Manufacturing and Survey Requirements. The “Guidelines” provide detailed requirements for the manufacturing processes and survey procedures of rigid wing sails, ensuring that their manufacturing quality meets design requirements. Through design approval, prototype testing, and surveys after installation on board, the “Guidelines” ensure that rigid wing sails undergo strict validation before being put into use, ensuring their safety and reliability.

2.Operational Requirements

The “Guidelines” not only demonstrate cutting-edge technical specifications but also clarify operational requirements, offering strong practicality and clear guidance for ship design, construction, and operation. The practicality is mainly reflected in the following four aspects:

(1) Detailed Drawings and Documentation Requirements. The “Guidelines” specify the drawings and documentation required during the design, manufacturing, and survey processes of rigid wing sails, ensuring that designers, manufacturers, and surveyors have a basis to rely on. Through detailed drawing and documentation requirements, the “Guidelines” ensure that the design and manufacturing processes of rigid wing sails are transparent and standardized.

(2) Clear Operational and Maintenance Requirements. The “Guidelines” require that ships be equipped with an approved rigid wing sail operating manual, clearly outlining the operational, inspection, maintenance, and safety requirements for rigid wing sails. Through a detailed operating manual, the “Guidelines” ensure that crew members can operate rigid wing sails correctly, avoiding safety accidents caused by improper operation.

(3) Scientific EEDI Calculation Method. The “Guidelines” provide a scientific method for calculating the Energy Efficiency Design Index (EEDI) for ships equipped with rigid wing sail-assisted propulsion systems, ensuring that the energy-saving effects of rigid wing sails can be accurately quantified. Through wind tunnel tests and sea trials, the “Guidelines” ensure that the energy-saving effects of rigid wing sails are scientifically verified, providing strong support for ship energy efficiency design.

(4) Requirements of Regular Operational Survey. The “Guidelines” require regular operational surveys of rigid wing sails to ensure that they remain in good working condition during ship operations. Through annual surveys and comprehensive inspections every five years, the “Guidelines” ensure that the structure and equipment of rigid wing sails do not pose safety hazards during long-term use.

Guidelines for Survey of Marine Wind-Rotor Assisted Propulsion System

Rotor sail propulsion technology is an innovative technology based on the Magnus effect. It uses electric motors to drive cylinders to rotate and generate thrust from the wind to assist ship propulsion, thereby reducing fuel consumption and carbon emissions. The application of this technology provides a brand-new energy-saving solution for the shipping industry. The “Guidelines for the Survey of Rotor Sail Propulsion Systems for Ships” (hereinafter referred to as the “Guidelines”) released by CCS not only fills the technical gap in the application of rotor sail propulsion systems on ships but also provides strong technical support for the global shipping industry's green transition.

1.Main Technical Content of the Guidelines

(1) Innovative Technical Standard Development. The “Guidelines” systematically propose design, construction, survey, and verification standards for rotor sail propulsion systems for the first time, covering the entire process of technical requirements from material selection, structural design to system integration.

The “Guidelines” not only clarify the design loads, structural strength, and stability requirements of the rotor sail propulsion system but also specify the technical requirements for the system’s electrical equipment, safety measures, control, and monitoring alarm systems. The establishment of these standards provides a guarantee for the safety and reliability of rotor sail propulsion systems and promotes the widespread application of this technology in the shipping industry.

(2) Innovative Methods for EEDI/EEXI Calculation. The “Guidelines” propose innovative methods for calculating the Energy Efficiency Design Index (EEDI) and the Existing Ship Energy Efficiency Index (EEXI). By introducing the thrust matrix and wind field probability matrix of the rotor sail propulsion system, a scientific basis is provided for quantifying the energy-saving effects of ships. This innovative method not only simplifies the calculation process of EEDI/EEXI but also provides a clear energy-saving effect assessment tool for ship designers and operators.

In addition, the “Guidelines” propose a verification method combining wind tunnel tests and numerical calculations to ensure the accuracy and reliability of the thrust matrix calculation results of the rotor sail propulsion system. The application of this method provides strong technical support for green technological innovation in the shipping industry.

2.Role of the “Guidelines”

(1) Comprehensive Technical Requirements to Aid Ship Design and Construction. The “Guidelines” provide comprehensive technical requirements from ship design, rotor sail construction, system integration to survey and verification. For ship designers, the “Guidelines” clarify specific requirements for the arrangement and design of rotor sail propulsion systems, overall longitudinal strength, local strength, stability, and other aspects, ensuring the safe installation and operation of the system on board.

The “Guidelines” specify in detail that the installation location of the rotor sail propulsion system must meet the requirements for the bridge's line of sight, not affect navigation safety, and comply with fire safety, explosion protection, lightning protection, and other requirements. These provisions provide ship designers with clear design references, avoiding potential safety hazards caused by improper system installation.

The “Guidelines” set out detailed requirements for the survey of wind rotor propulsion systems, covering the entire process of surveys during and after construction. During the construction survey phase, the guidelines require testing of the functions of the rotor propulsion system to ensure correct installation and reliable operation. In the post-construction survey phase, the “Guidelines” call for annual and special surveys to inspect the base, supporting components, safety systems, and other elements of the rotor propulsion system, ensuring its long-term safe operation.

Moreover, the “Guidelines” stipulate non-destructive testing (NDT) requirements for rotor propulsion systems to ensure the welding quality and structural integrity of key components. The establishment of these survey standards provides ship operators with a basis for system maintenance and management, ensuring the safety and reliability of the system throughout its entire life cycle.

(2) Quantitative Assessment of Energy-Saving Effects to Boost Ship Energy Efficiency. The “Guidelines” provide a scientific basis for the quantitative assessment of energy-saving effects by introducing the thrust matrix and wind field probability matrix. Ship designers and operators can use the methods provided in the “Guidelines” to calculate the energy-saving effects of rotor propulsion systems under different wind conditions, optimize system operation strategies, and maximize energy-saving effects.

The “Guidelines” propose a method for calculating the thrust matrix of rotor propulsion systems. By determining the thrust coefficient of the system through wind tunnel tests or numerical calculations and combining it with the global wind field probability matrix, the energy-saving effects of the system under different wind conditions can be calculated. The application of this method provides ship operators with a clear tool for assessing energy-saving effects, helping to enhance ship energy efficiency.