Of all the designs we've seen for boats, engines, and propellers, we can guarantee you haven't seen anything like this before.
It's no secret at the Blurb that we appreciate the fine art of #WeirdBoats. We've devoted countless articles to the most interesting and unusual designs that boating has to offer. Boating, for all its quirks and foibles, is always innovating, and those innovations have led down some unusual rabbit holes. Peculiar hull shapes, upside down engine designs, and funky features pop up constantly as designers and engineers try to find a competitive edge (or a good marketing strategy). Very rarely does a boat propeller get #WeirdBoat treatment, but this one cannot be ignored.
Enter BluNav, an electric propulsion company from France who specializes in developing electric motors and alternative propulsion systems for recreational boats. Part of the company's mantra is to "accelerat(e) the energy transition by envisioning a global ecosystem centered on clean energy and propulsion."
The company is making headway across the European market thanks to several clever designs that include an electric outboard motor, digital navigation software, and a unique take on the traditional design ethos. The company's CEO, Xavier Lacherade, says their "essential purpose is to support sustainable navigation, allowing individuals for bliss and closeness to nature."
What stands out the most, and what is catching the eye of boating purists, is BluNav's unique propeller design for their BlueSpin electric motor.
In an article with News Atlas, the design is called a "biomimetic hubless outboard motor," which might seem like a bunch of jargon, but is actually the perfect description.
The blades, which the company aptly calls it's Whale Design propeller, mimic the shape and contour of a Blue Whale fin. And not a little bit, either. The propeller blades are identical to three whale fins, albeit placed within a circular hub.
The standout detail of the whale fin design is that the blades aren't smooth. Quite the opposite. Blue Whale fins have a bumpy leading edge that's very prominent. On actual whales, these bumps are called tubercles. Throw away whatever mental image you're conjuring about a smooth stainless steel prop. This is the exact opposite.
According to biologists, the tubercles on a whale improve hydrodynamic efficiency by channeling water flow and reducing drag. This unique natural adaptation has been noticed by science for its potential technological applications, as even the NIH (National Institutes of Health) has published multiple studies about whale tubercles and their potential for "bio-inspired technology."
You can see why a startup like BluNav picked up on the concept when you read from one NIH study, which states "(t)he tubercles on the leading edge act as passive-flow control devices that improve performance and maneuverability of the flipper... Control of passive flow has the advantages of eliminating complex, costly, high-maintenance, and heavy control mechanisms, while improving performance for lifting bodies in air and water. The tubercles on the leading edge can be applied to the design of watercraft, aircraft, ventilation fans, and windmills."
To bring the whale fin concept to life, BluNav used their existing BlueSpin electric motor and designed the whale fins using CAD. Since propeller blades are thinner than whale fins, the tubercles were modified to resemble 'crests' instead of nodes. From there, the company began testing various blades to find maximum efficiency.
Another key to the design lies within the circular hub that encases the propeller. The electric prop drive is a 'drop-in' system that can be added to the transom, or installed through the center of the hull. The rectangular shape of the cowling and shaft allows for easy installation, but the hub itself is a circular ring that is magnetically driven. This technique minimizes friction within the hub, which in turn improves efficiency. Given BluNav's current BlueSpin motors are 5 kW and 8 kW respectively, every improvement in efficiency means longer battery life and greater range. The magnetic inner ring also operates more quietly than traditional gas-powered shafts, uses fewer components, and requires less maintenance than a standard prop drive.
The company says that their Smart Hybrid Boating Solution, which includes the BlueSpin motor and Whale Fin prop, will serve as an add-on propulsion system until the company ramps up its power capabilities. The idea is to use the electric power at low speeds before retracting it out of the water when higher speeds are required from the gas-powered engine. In other words, it's a 'plug and play' solution for those who want a high efficiency and silent propulsion system when traveling at low speed needs through small lakes and rivers, marinas, or harbours, or where gas-powered travel is not authorized. Implementing BluNav's smart navigation technology also allows users to work in sync between their BlueSpin motor and their larger gas-powered engine depending on the situation and their needs. The company's software suite includes features like 'virtual anchor,' heading hold, and cruise control.
BluNav first revealed the Whale Fin design at boot Düsseldorf in January and is already expanding their offering. They also intend to showcase the Whale Fin at several upcoming shows. The company says they will offer the BlueSpin motor with three, four, and five blade configurations.
You can get an inside look at their designs and philosophy in the video below:
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