Gu Yajuan, CCS Shanghai Rules & Research Institute  

In recent years, with the acceleration of international shipping emissions reduction, the application of wind-assisted propulsion technology onboard ships has also attracted increasing attention from the industry. Currently, sail-assisted propulsion technology is regarded as one of the technologies that can substantially help ships meet the EEDI Phase III greenhouse gas emission requirements, following the dual fuel technology. It is also applicable to a wide range of ship types, almost all cargo ships and passenger ships. 

China Classification Society (CCS) has always been committed to encouraging and promoting the shipboard application of new technologies and products, and continuously improving its technical service capabilities in wind-assisted propulsion technology. At present, CCS has completed the approval and other services for marine wind-rotor assisted propulsion system from multiple domestic and foreign companies, and has also completed the design review and survey of full-scale ship projects.

1. AIP and Type Approval

In terms of AIP, CCS has issued AIP certificates for wind-assisted propulsion technology to multiple enterprises, including the “Rotor Sail” system of CSIC Shanghai Marine Energy Saving Technology Development Co., Ltd. (CMES-Tech), the wind rotor-assisted propulsion system of Dealfeng New Energy Technology (Tianjin) Co., Ltd. (Dealfeng). 

In terms of type approval, in December 2023, CCS issued the world’s first type approval certificate for the wind rotor-assisted propulsion system of Dealfeng, which marks the authoritative approval of this technology with regard to safety, reliability, and practicality. 

From the projects completed by CCS, it can be found that the marine wind rotor-assisted propulsion system is widely applicable to various ship types. Generally speaking, as long as there is sufficient outdoor deck area, it can be applied. It can not only be used for the installation on newbuildings, but also requires only minimal structural reinforcement when retrofitting existing ships. Therefore, it has broad application and promotion prospects, and is a technical option for ships to achieve energy-saving and emissions reduction goals. CCS can provide technical services for ship owners, and customize technical solutions for improving the energy efficiency of fleets or individual ships.

2. Safety Risk Assessment

During shipboard application of wind rotors, it is inevitable to consider the compatibility between systems, the compliance with various rules, regulations, and codes, including the calculation of yield and buckling strength, fatigue, etc. involved in the inner tower, base, main hull, outer cylinder structure, related electrical system arrangement, rotor structure arrangement, and hull arrangement. To promote the uptake of new technology and equipment, CCS will provide risk assessment services for ship design/retrofitting scheme, in order to effectively control various risks that may arise during application. The following are the main safety risk assessment points:

(1) Structural Strength Risk

The rotor-assisted propulsion system is installed on the open deck of the ship and is directly subjected to environmental loads including wind, waves, ice, snow, etc. The rotor, inner tower, and base structure of the system may withstand significant dynamic loads under extreme sea conditions, which may lead to structural fatigue, deformation, and even fracture.

(2) Electrical System Risk

The drive motor, control system, and power supply system of the rotor-assisted propulsion system may fail in harsh environment, such as motor overheating, control system failure, short circuit of cables, etc. 

(3) Fire Risk

The inner tower of the rotor-assisted propulsion system is equipped with a drive motor and electrical equipment, which may cause fire due to equipment overheating or electrical failure in the case of long-term operation, especially in hazardous areas.

(4) Risk of Decreased Stability

The rotor-assisted propulsion system generates additional lateral moment during operation, which has a negative impact on the stability of the ship, especially in the case of sudden wind. In addition, in the event of loading minerals with high water content, the adverse factors of stability may accumulate, which requires special consideration.

(5) Maneuverability Risk

The rotor-assisted propulsion system may have adverse effects on the maneuverability of the ship during operation, especially in terms of directional stability, turning ability, and stopping ability under strong wind or complex sea conditions, the forces generated by the system may lead to a decline in the ship’s performance.

(6) Maintenance and Operation Risk

The rotor-assisted propulsion system should be maintained and operated by professional technicians. Improper operation or untimely maintenance may lead to system failure or reduced performance.

3. Integrated Services

For the wind rotor technology application parties including shipowners, shipyards, and design units, CCS can provide feasibility analysis, risk assessment, design assessment, load assessment, structural strength assessment, energy efficiency assessment, etc., and provide technical support for scheme decision-making to ensure the achievement of the carbon reduction goals.

For the wind rotor supplier, CCS can not only provide AIP service, type approval, product approval, and survey services to ensure the safety, reliability, and durability of the equipment, but also can provide technical support for the development of its product series, promote the formation of a product series, effectively control product costs, ensure the supply time, and promote the formation of a win-win situation between the technology application party and the supplier, thus entering a virtuous cycle.

At present, CCS has strong technical service capabilities in wind-assisted propulsion technology. Through rules formulation, technical certification, support for full-scale ship projects, and international cooperation, it will continuously promote the application and development of this technology on ships, and provide strong support for the green transition of the shipping industry. It is worth mentioning that CCS’s service capabilities in the field of wind-assisted propulsion technology have also gained international recognition. For example, the wind rotor-assisted propulsion system of Dealfeng has also been recognized by the International Maritime Organization (IMO) and included in the EEDI energy efficiency formula after being approved by CCS.