As a revolutionary innovation in the propulsion technology of ships and underwater equipment, rim-driven thrusters, with their shaftless and integrated design advantages, have achieved performance breakthroughs in high efficiency, energy saving, low noise, environmental protection, and flexible maneuverability. Their size range covers a wide spectrum from centimeter-level to meter-level, adapting to diverse needs from micro underwater robots to large ocean-going ships. From deep-sea exploration to green shipping, rim-driven thrusters of different sizes are becoming core power units for various surface and underwater equipment, outlining a clear size-application matching landscape.

Giant-Scale: Large Rim-Driven Thrusters with Power as the Priority

The core design of large rim-driven thrusters is to meet the thrust requirements of heavy-duty ships. Their size is positively correlated with power. Currently, mature large-scale products in the industry have achieved a propeller diameter exceeding 2.5 meters and a power level of several thousand kilowatts. By integrating high-power permanent magnet motors and abandoning traditional shafting systems, these thrusters not only improve propulsion efficiency but also significantly reduce vibration and noise, making them an ideal choice for special ships and large commercial ships.

Among specific products, the RD-AZ series of rim-driven permanent magnet thrusters launched by Kongsberg Maritime are highly representative. The RD-AZ-2600 model has a propeller diameter of 2600 millimeters, while the newly added RD-AZ-2300 model has a diameter of 2300 millimeters. The power range covers the needs of medium and large ships, and it is particularly suitable for scenarios with strict requirements on maneuverability and low noise, such as offshore wind farm service vessels and scientific research ships. Rolls-Royce, an international giant, has further raised the power ceiling to 2600 kilowatts with its TT-PM series of rim-driven thrusters. Its TT-PM2600 model, relying on strong thrust output, can be adapted to the main propulsion system of large transport ships, ferries and other vessels.

Domestically, China has achieved independent research and development of megawatt-class rim-driven thrusters and exported them to Russia, breaking international monopolies. This thruster can be applied to large fishing boats, patrol boats and other ships, marking China's entry into the international advanced ranks in the field of large rim-driven thrusters. The GRM150 large contra-rotating rim thruster developed by Guangzhou Marine Engineering has a maximum power of 1000 kilowatts and has become a core propulsion equipment for transport ships and tugboats, demonstrating the practical capabilities of domestic large rim-driven thrusters.

Micro-Precision: Millimeter-Level Power Units for Deep-Sea Exploration

Different from the power-oriented large-scale products, micro rim-driven thrusters take compactness and light weight as their core design concepts. The minimum size has broken through the 10-centimeter level, and the propeller diameter of some products is only 65 millimeters, with a weight of less than 3 kilograms. However, they can provide stable power in extreme environments, making them core power components for underwater robots and micro submersibles. The key advantages of such thrusters lie in the shaftless design that avoids entanglement risks, as well as high waterproof level and high pressure resistance, which can be adapted to harsh scenarios such as deep-sea exploration.

The POD-S 0.5 model rim-driven thruster from Beijing Ocean Strategy Technology is a typical representative of micro products. Its propeller diameter is only 65 millimeters, input power is 0.5 kilowatts, thrust can reach 7 kilograms, and weight is only 2.5 kilograms. It meets the IP68 waterproof standard and can be adapted to micro underwater equipment such as AUV (Autonomous Underwater Vehicle) and ROV (Remotely Operated Vehicle). The standard working depth is 50 meters, and a 3000-meter deep-water version is available as an option to meet the needs of medium and deep-sea scientific research. The TR07B shaftless rim-driven thruster from Ocean Intelligence also demonstrates micro-miniaturization advantages, with a diameter of 132 millimeters, a weight of 2.1-2.7 kilograms, and a power of 800 watts, which can be flexibly integrated into small underwater detection equipment.

More breakthroughly, the RIM series thrusters from Haoye Technology, whose micro models can support extreme depth operations of 11,000 meters, are perfectly adapted to the auxiliary propulsion of deep-sea UUV and the main propulsion of ROV. They can maintain stable and reliable power output under extreme pressure environments, providing core technical support for exploring the mysteries of the deep sea.

Full-Scenario Coverage: Diverse Application Equipment Corresponding to Size Gradients

A precise matching relationship has been formed between the size gradient of rim-driven thrusters and application scenarios. From micro to large scale, they cover three core fields: underwater equipment, small and medium-sized ships, and large commercial and special ships, showing strong adaptability.

In the field of underwater equipment, micro rim-driven thrusters with a diameter of 65-200 millimeters are the absolute main force, widely used in underwater robots such as AUV and ROV, as well as small deep-sea detectors. Such equipment has extremely high requirements on the volume, weight and reliability of the power system. The shaftless design of rim-driven thrusters, which has the advantage of no entanglement, IP68 waterproof performance and deep-sea high-pressure adaptability, makes them the preferred power solution in this field. For example, 3000-meter-level deep-water thrusters have been routinely used in scientific research tasks such as marine geological exploration and biological observation, while 11,000-meter-level products help in abyssal scientific exploration.

In the field of small and medium-sized ships, rim-driven thrusters with a diameter of 0.45-2.0 meters have formed a serialized product line, with power covering 30-1000 kilowatts, adapting to new energy ships, tourist ships, small ferries, fishing boats and other vessels within 40 meters. The 7-blade series thrusters from the Dutch company VanderVelden Marine System have a propeller diameter ranging from 0.45 to 1.05 meters and a power of 30-295 kilowatts, which have been put into mass application; the GRT70, GRM260 and other models of thrusters from Guangzhou Marine Engineering have a maximum power of 150 kilowatts, which can be used as the main propulsion or side thrust system for small ships, helping the development of green shipping with their high efficiency and energy-saving characteristics.

In the field of large commercial and special ships, high-power rim-driven thrusters with a diameter of more than 2.0 meters undertake the main propulsion task, and are applied to offshore wind farm service vessels, scientific research ships, transport ships, tugboats and other ships. The Kongsberg RD-AZ series, Rolls-Royce TT-PM series and domestic megawatt-class thrusters, relying on their advantages of high torque output and low underwater radiated noise, not only meet the thrust requirements of large ships, but also adapt to the harsh operating environment of offshore wind farms and the low-noise requirements of scientific research ships. Among them, the models applied to scientific research ships have passed the DNV Silent R classification certification, which can effectively reduce the interference to the marine ecosystem.

Technological Evolution: Synergetic Expansion of Size Boundaries and Application Scenarios

The expansion of the size of rim-driven thrusters and the expansion of application scenarios have always been in a state of synergetic evolution. Since the 1990s, foreign countries have taken the lead in launching engineering exploration of rim-driven thrusters. From the test of the U.S. Navy SES-200 ship to the serialized product research and development by Dutch and Norwegian enterprises, the technological breakthrough from small and medium-sized to large-scale products has been gradually realized; domestically, starting from the principle prototype during the "Eighth Five-Year Plan" period, China has gradually overcome the core technologies of megawatt-class large-scale products, and at the same time achieved breakthroughs in the field of micro deep-sea thrusters, forming full-size coverage capabilities.

In the future, with the advancement of permanent magnet motor technology, sealing technology and material science, the size boundary of rim-driven thrusters will be further expanded——micro products may develop towards smaller size and lower power consumption, adapting to micro bionic underwater robots; large-scale products will pursue higher power density to meet the propulsion needs of ultra-large ships and offshore platforms. At the same time, characteristics such as low noise, energy saving and deep-sea adaptability will be further strengthened, promoting their application in more high-end equipment and becoming the core power support for the marine economy and deep-sea exploration.