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Becker Mewis Duct
The Becker Mewis Duct® is a hydrodynamic energy-efficiency solution that is installed in front of the propeller to optimize the flow of water toward the propeller. By smoothing out the stern wake and creating a controlled pre-swirl, the propeller’s operating conditions are improved, leading to higher propulsion efficiency, lower fuel consumption, and reduced emissions. Unlike a traditional nozzle, the Becker Mewis Duct® consists of two interacting components—a hydrodynamically designed nozzle ring and an integrated fin system. The nozzle ring directs and accelerates the water flow toward the propeller, while the fins create a counter-rotating water flow that reduces the rotational losses that normally occur behind the propeller. This combination allows a greater portion of the engine power to be converted into usable propulsion. Each Becker Mewis Duct® is individually sized using CFD simulations and model tests to adapt to the vessel’s hull shape, propeller, and operational profile. The solution can be installed both on newbuilds and as a retrofit during routine dry-docking and is currently used on a large number of ships worldwide.
How does the Becker Mewis Duct® work?
Bulky and relatively slow-moving ship hulls often create an uneven inflow to the propeller. This means that the propeller blades are subjected to varying loads with each revolution, leading to energy losses, vibrations, and lower propulsion efficiency. The Becker Mewis Duct® counteracts these losses by stabilizing and accelerating the inflow while the integrated fins generate a controlled counter-rotation (pre-swirl). This reduces the rotational losses that would otherwise occur in the propeller flow, improving the propeller’s efficiency and reducing power requirements.
In addition to improved energy efficiency, the solution can also contribute to lower vibration levels, reduced cavitation, and improved course stability.
When is the Becker Mewis Duct® suitable?
The Becker Mewis Duct® is designed for vessels with fuller hull forms and relatively low service speeds where the propeller operates under high loads.
The solution is particularly suitable for:
- Tankers
- Shuttle tankers
- Bulk carriers
- LNG and LPG carriers
- Dry cargo ships
- Heavy-lift ships
- Car carriers
On these vessels, the solution can deliver significant energy savings while reducing emissions and operating costs. The magnitude of the savings depends on the interaction between the hull, propeller, and operating profile, but model tests and full-scale installations typically show efficiency gains of 3–8%, and in some applications up to about 10%.
Benefits of the Becker Mewis Duct®
- Optimizes water flow in front of the propeller.
- Creates a controlled pre-swirl that reduces rotational losses.
- Improves propulsion efficiency.
- Can reduce fuel consumption and emissions.
- Contributes to lower vibration levels and reduced cavitation.
- Customized using CFD simulations and model testing.
- Suitable for both new construction and retrofits.
- Has no moving parts and requires virtually no additional maintenance.