Independent Research and Development of High-precision Energy-saving Marine Propellers

Entering the third decade of the 21st century, the global shipping industry is undergoing an unprecedented green transformation. The new regulations on the Energy Efficiency Existing Ship Index (EEXI) and Carbon Intensity Indicator (CII) issued by the International Maritime Organization (IMO) have officially entered into force, imposing mandatory requirements on the carbon emission intensity of operational vessels. Ships failing to meet the standards will face penalties including navigation restrictions and phasing-out. Industry statistics show that more than half of the world's existing vessels need technical retrofits to comply with the new energy efficiency requirements, and replacing propellers with high-performance ones stands as one of the most cost-effective retrofit solutions.

For a long time, the high-end marine propeller market has been monopolized by a small number of international giants, with core design technologies and high-precision machining processes held by enterprises from developed countries. Domestic shipping companies not only have to pay procurement prices several times the production cost but also frequently suffer from lengthy delivery cycles and slow after-sales service responses. Against this backdrop, the independent research, development and industrialization of high-precision energy-saving marine propellers can not only fill the gaps in domestic industries and cut retrofit costs for domestic shipping enterprises, but also advance the high-end and green upgrading of China's shipbuilding industry, enabling the country to seize the initiative in global green maritime competition.

Technically speaking, high-precision energy-saving marine propellers have far stricter standards in design, manufacturing and inspection compared with conventional counterparts. Traditional propellers mostly focus solely on thrust output, attaching inadequate importance to hydrodynamic optimization and energy consumption reduction, and feature low manufacturing precision with blade surface deviations often exceeding 1 millimeter, which directly impairs propulsion efficiency. In contrast, through systematic optimization of blade curved surfaces, guide wheels and vortex-eliminating fins, high-precision energy-saving marine propellers drastically reduce water flow resistance and energy loss while keeping manufacturing precision within 0.1 millimeter. This ultimately cuts fuel consumption by 8% to 10%. For vessels in long-term service, this translates to annual fuel cost savings of millions or even tens of millions of yuan, alongside remarkable emission reduction outcomes.

At the core equipment level, the enterprise has independently developed the first domestic large-scale laser automatic measuring equipment for propeller blades in the industry, achieving full substitution of similar foreign products. Its measurement precision is less than 0.1 millimeters, which fully meets the inspection requirements for high-precision propellers. The procurement and operation costs are reduced by more than 50% compared with imported equipment, resolving the bottleneck issue in the inspection process. Meanwhile, the enterprise pioneered the robotic processing technology for large propellers nationwide and realized its large-scale application. It independently developed a control system adapted to the processing technology, which can automatically adjust the machining path according to the curved surface parameters of propellers. Both machining precision and efficiency have reached internationally advanced levels, enabling independent control over core production equipment and processes from the source.

In terms of casting processes, to address defects in large propellers, the enterprise has conducted research on the formation mechanism of casting defects in propellers. By optimizing smelting processes and improving pouring procedures, zero defects have been achieved in hazardous areas specified by relevant standards, greatly enhancing product quality. To tackle casting deformation problems, the enterprise mastered the law of curved surface deformation through extensive experimental research and developed targeted deformation control technology. This has cut curved surface deformation by over 60%; the machining allowance for blade profiles has been reduced from approximately 10 mm on each side to 5 mm, and even 1 to 2 mm for some products. This significantly lowers machining costs, shortens production cycles, and reduces raw material waste and environmental pollution generated during processing.

At the design and R&D level, the enterprise has precisely targeted the demand for green transformation in the global shipping industry and carried out in-depth collaborative research with top domestic universities including Jiangsu University of Science and Technology. It has built a database containing tens of thousands of ship type parameters, allowing rapid matching of optimal propeller design schemes for various vessel types. The enterprise has systematically optimized the structures of propellers, guide wheels and vortex-eliminating fins, developing a high-precision energy-saving marine propulsion system with fully independent intellectual property rights. This system can slash the energy consumption of operating ships by 8% to 10%, fully complying with the EEXI energy efficiency standards and IMO requirements for ship energy efficiency and emissions. By 2026, the enterprise has built a technical barrier consisting of 44 valid patents, won major awards such as the National Marine Science and Technology Progress Award, undertaken multiple national special R&D programs, and been recognized as a national-level "Little Giant" enterprise specializing in sophisticated, unique and innovative products.

The ultimate goal of independent research and development is to achieve industrial application and serve the green transformation of the global shipping industry. After years of development, China's independently developed high-precision energy-saving marine propellers have achieved a leap from technological breakthroughs to large-scale market application, winning widespread recognition in domestic and overseas markets.

Data from Zhenjiang Tongzhou Propeller indicates that the company's high-precision energy-saving marine propulsion systems held a national market share of 19.63% in 2024, which further rose to 26.55% in 2025. It firmly ranks among the first echelon in the domestic segmented sector, with delivery volumes ranking among the world's top three. As of May 2025, the enterprise's comprehensive hydrodynamic energy-saving solutions have been applied to nearly 10,000 vessels worldwide, saving a total of 276 million US dollars in fuel costs and cutting carbon emissions by more than 240,000 tonnes, contributing China's strength to the green transformation of the global shipping industry.

In the market for vessel energy-saving retrofits, independently developed high-precision energy-saving propellers deliver outstanding cost performance. Taking the energy-saving retrofit project for a 2824 TEU vessel delivered at Turkey's Yalova Port as an example: after the retrofit undertaken by Zhenjiang Tongzhou, the vessel's fuel consumption is projected to drop by approximately 10%. In contrast to the cumbersome hull dismantling work required for engine replacement, propeller replacement only takes 3 to 6 months from design and production to completion, allowing vessels to resume operations immediately after installation. Its retrofit cost is roughly one-third that of engine replacement, making it the most cost-effective vessel energy-saving retrofit solution available at present and highly favoured by shipowners across the globe. In 2025, the enterprise's export business surged by over 50% year-on-year, with its products exported to numerous countries including Turkey, the United Arab Emirates, Vietnam and Singapore, serving world-leading shipping corporations such as Maersk Line, Mediterranean Shipping Company and CMA CGM.

The industrial scale keeps expanding continuously. Zhenjiang Tongzhou Propeller posted an output value of 150 million yuan in 2022, with its projected output value set to reach 1 billion yuan in 2025, representing a more than fivefold increase within three years and reflecting robust market demand. A host of enterprises dedicated to the research and development of high-precision energy-saving marine propellers have emerged in other domestic regions, gradually forming a complete industrial chain covering design, manufacturing, inspection and services. This has overturned the previous situation of total reliance on imports, driven domestic propeller market prices back to a reasonable range, and lowered the overall green retrofit costs for the shipping sector.

Meanwhile, independent research and development has boosted the growth of domestic supporting industries. Rising demand for laser inspection equipment, industrial robots and high-end casting raw materials has advanced China's high-end equipment manufacturing sector, fostering sound industrial interaction and underpinning the independent controllability of the entire high-end equipment manufacturing industry.