New BlueNav propeller design makes a ‘whale’ of a difference

Using the science of biomimetic design, the new Whale Design BlueNav propeller uses learning from studying the flippers and fins of some of the ocean’s most powerful swimmers to increase efficiency and performance on the company’s BlueSpin electric-hybrid system.

The words biomimetic or biomimicry come from the ancient Greek for life (bios) and imitating (mimesis). It is “the study of the formation, structure, or function of biological mechanisms and processes for the purpose of synthesizing similar products by artificial mechanisms.”

BlueNav propeller has ‘tubercle’ leading edge

There has been considerable research and analysis of how cetaceans (whales and dolphins) are able to move through water with such incredible ease, fluidity and efficiency.

What the studies show is surprising. Traditional engineering of things like propeller blades and wings includes smooth edges, partly because industrial engineering involves cost efficiencies and things with smooth edges are relatively easy and inexpensive to manufacture.

They also ensure a steady air or water flow, which would intuitively seem to be a good thing.

Whale fin showing inspiration for BlueNav propeller design
Photo by aurore murguet: pexels

Whale flippers, though, have bumps on their edges (see image above), called tubercles. As the whale swims, those tubercles create small vortices – whirlpools – behind the flipper. It turns out that this unsteady flow of water actually increases lift and reduces drag better than a smooth edge.

This knowledge has been applied in wind turbines and fans since about 2018, and has shown that biomimetic tubercle blades can help wind farms produce up to 20% more power and increase airflow by up to 25% in industrial blowers.

Adapted from wind turbine technology

The BlueNav engineers decided to investigate how the application might work in the water. It’s not exactly the same as a wind turbine, because the BlueNav electric motor is a rim drive with a different set-up. Instead of the propeller blades being attached to a central axle, they are attached to the outer rim of the device. The water flows through the middle.

What their CFD (Computational Fluid Dynamics) data showed was similar to the wind turbines – the whale-mimicking blade edge reduces drag and increases fluid flow efficiency. The new Whale Design BlueNav propeller will be introduced on their BlueSpin motor systems in the next few months.

BlueNav’s BlueSpin systems are an innovative way for fossil fuel boat owners to easily and affordably switch to hybrid propulsion. The increased efficiency of the new design will be an additional appeal for those who may have concerns about electric propulsion range.

The French company was founded in 2020 to focus on gas/petrol /diesel boat owners – both commercial and leisure – who would like to reduce their environmental impact but find it difficult to go all-electric, and financially impractical to do a complicated hybrid refit.

As Plugboats wrote in its first article about BlueNav, “The BlueSpin system is a fast and simple solution for hybrid boat conversion. A retractable electric motor, easily adapted to any boat, allows the pilot to switch from fossil fuel to electric propulsion at the touch of a button.”

Read more about BlueNav in Plugboats

The system can be quickly installed in-hull, under the hull or on the transom.

One of the especially attractive aspects of BlueSpin is the HMI (Human Machine Interface) that seamlessly integrates with existing navigation systems from all major electronics companies. The HMI analyzes data about current, position and speed to assist the pilot in switching from one propulsion system to the other and can also be augmented with options like self parking and dynamic positioning.

BlueSpin was nominated in the 2021 Dame Design Awards of METSTRADE and took top honours for Best Product at the Innovation Awards of the Salon Nautique Paris in the same year.

“We are proud to introduce the Whale Design, a testament to our dedication to progress and sustainable engineering” said Hervé FROUIN, co-founder & CTO of BlueNav. “Our mission has always been to push the boundaries of what is possible, and with this innovative design, we are one step closer to achieving that goal.”


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